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Enko D, Meinitzer A, Zelzer S, Herrmann M, Artinger K, Rosenkranz AR, Zitta S. Vitamin D metabolism in living kidney donors before and after organ donation. Clin Chem Lab Med 2022; 60:1218-1224. [PMID: 35514251 DOI: 10.1515/cclm-2022-0148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/29/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Living kidney donors provide a unique setting to study functional and metabolic consequences after organ donation. Since the lack of data of the homoeostasis of numerous vitamin D metabolites in these healthy subjects, the aim of this study was to assess the vitamin D metabolism before and after kidney donation. METHODS We investigated the 25-dihydroxyvitamin D2 (25[OH]D2), 25-dihydroxyvitamin D3 (25[OH]D3), 1,25-dihydroxyvitamin D3 (1,25[OH]2D3), 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), 25,26-dihydroxyvitamin D3 (25,26[OH]2D3), and the native vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) in a well characterized study cohort of 32 healthy living kidney donors before and after organ donation. RESULTS Thirty-two healthy subjects after kidney donation had significantly lower median (interquartile range) 1,25(OH)2D3 serum concentrations (88.6 [62.6-118.8] vs. 138.0 [102.6-152.4] pmol/L, p<0.001) and significantly higher median 25(OH)D2 serum levels (1.80 [1.19-2.19] vs. 1.11 [0.74-1.59] nmol/L, p=0.019) than before donation. Similar serum concentrations of 25(OH)D3 and 25,26(OH)2D3 were observed before and after donation. The 24,25(OH)2D3 blood levels distinctly decreased after organ donation (4.1 [2.3-5.3] vs. 5.3 [2.2-6.9] nmol/L, p=0.153). Native vitamin D2 (0.10 [0.08-0.14] vs. 0.08 [0.06-0.12] nmol/L, p=0.275) was slightly increased and vitamin D3 (1.6 [0.6-7.2] vs. 2.5 [0.9-8.6] nmol/L, p=0.957) decreased after kidney donation. CONCLUSIONS Living kidney donors were found with decreased 1,25(OH)2D3 and 24,25(OH)2D3, increased 25(OH)D2 and consistent 25(OH)D3 and 25,26(OH)2D3 serum concentrations after organ donation. The current study advances the understanding on vitamin D metabolism suggesting that altered hydroxylase-activities after donation is accompanied by compensatory elevated dietary-related 25(OH)D2 blood concentrations.
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Affiliation(s)
- Dietmar Enko
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
- Institute of Clinical Chemistry and Laboratory Medicine, General Hospital Hochsteiermark, Leoben, Austria
| | - Andreas Meinitzer
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Sieglinde Zelzer
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Markus Herrmann
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Katharina Artinger
- Department of Internal Medicine, Division of Nephrology, Medical University of Graz, Graz, Austria
| | - Alexander R Rosenkranz
- Department of Internal Medicine, Division of Nephrology, Medical University of Graz, Graz, Austria
| | - Sabine Zitta
- Department of Internal Medicine, Division of Nephrology, Medical University of Graz, Graz, Austria
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Hsu S, Zelnick LR, Lin YS, Best CM, Kestenbaum B, Thummel KE, Rose LM, Hoofnagle AN, de Boer IH. Differences in 25-Hydroxyvitamin D Clearance by eGFR and Race: A Pharmacokinetic Study. J Am Soc Nephrol 2021; 32:188-198. [PMID: 33115916 PMCID: PMC7894669 DOI: 10.1681/asn.2020050625] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 09/08/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Conversion of 25-hydroxyvitamin D (25[OH]D) to the active form of vitamin D occurs primarily in the kidney. Observational studies suggest 25(OH)D clearance from the circulation differs by kidney function and race. However, these potential variations have not been tested using gold-standard methods. METHODS We administered intravenous, deuterated 25(OH)D3 (d-25[OH]D3) in a pharmacokinetic study of 87 adults, including 43 with normal eGFR (≥60 ml/min per 1.73 m2), 24 with nondialysis CKD (eGFR <60 ml/min per 1.73 m2), and 20 with ESKD treated with hemodialysis. We measured concentrations of d-25(OH)D3 and deuterated 24,25-dihydroxyvitamin D3 at 5 minutes and 4 hours after administration, and at 1, 4, 7, 14, 21, 28, 42, and 56 days postadministration. We calculated 25(OH)D clearance using noncompartmental analysis of d-25(OH)D3 concentrations over time. We remeasured 25(OH)D clearance in a subset of 18 participants after extended oral vitamin-D3 supplementation. RESULTS The mean age of the study cohort was 64 years; 41% were female, and 30% were Black. Mean 25(OH)D clearances were 360 ml/d, 313 ml/d, and 263 ml/d in participants with normal eGFR, CKD, and kidney failure, respectively (P=0.02). After adjustment for age, sex, race, and estimated blood volume, lower eGFR was associated with reduced 25(OH)D clearance (β=-17 ml/d per 10 ml/min per 1.73 m2 lower eGFR; 95% CI, -21 to -12). Black race was associated with higher 25(OH)D clearance in participants with normal eGFR, but not in those with CKD or kidney failure (P for interaction=0.05). Clearance of 25(OH)D before versus after vitamin-D3 supplementation did not differ. CONCLUSIONS Using direct pharmacokinetic measurements, we show that 25(OH)D clearance is reduced in CKD and may differ by race. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER Clearance of 25-hydroxyvitamin D in Chronic Kidney Disease (CLEAR), NCT02937350; Clearance of 25-hydroxyvitamin D3 During Vitamin D3 Supplementation (CLEAR-PLUS), NCT03576716.
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Affiliation(s)
- Simon Hsu
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
- Kidney Research Institute, University of Washington, Seattle, Washington
| | - Leila R. Zelnick
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
- Kidney Research Institute, University of Washington, Seattle, Washington
| | - Yvonne S. Lin
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Cora M. Best
- Kidney Research Institute, University of Washington, Seattle, Washington
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Bryan Kestenbaum
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
- Kidney Research Institute, University of Washington, Seattle, Washington
- Department of Epidemiology, University of Washington, Seattle, Washington
| | - Kenneth E. Thummel
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Lynn M. Rose
- Department of Pharmacy, University of Washington, Seattle, Washington
| | - Andrew N. Hoofnagle
- Kidney Research Institute, University of Washington, Seattle, Washington
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Ian H. de Boer
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington
- Kidney Research Institute, University of Washington, Seattle, Washington
- Veterans Affairs Puget Sound Health Care System, Seattle, Washington
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Vitamin D Metabolic Ratio and Risks of Death and CKD Progression. Kidney Int Rep 2019; 4:1598-1607. [PMID: 31891001 PMCID: PMC6933450 DOI: 10.1016/j.ekir.2019.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/15/2019] [Accepted: 08/19/2019] [Indexed: 12/28/2022] Open
Abstract
Introduction Assessment of impaired vitamin D metabolism is limited by lack of functional measures. CYP24A1-mediated vitamin D clearance, calculated as the ratio of serum 24,25-dihydroxyvitamin D3 to 25-hydroxyvitamin D3 (the vitamin D metabolic ratio, VDMR), is induced by 1,25-dihydroxyvitamin D and may assess tissue-level activity. We tested associations of the VDMR with risks of death and progression to end-stage renal disease (ESRD) in patients with chronic kidney disease (CKD). Methods We studied participants from the Chronic Renal Insufficiency Cohort (CRIC), which included a random subset of 1080 CRIC participants plus additional participants who experienced ESRD or died (case cohort study design). Serum 24,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 was measured 1 year after enrollment. The primary outcomes included death and progression to ESRD. Using inverse probability weighting, we tested associations of VDMR (24,25[OH]2D3/25[OH]D3) with risks of death and ESRD, adjusting for demographics, comorbidity, and kidney function (estimated glomerular filtration rate [eGFR] and urine protein-to-creatinine ratio [PCR]). Results There were a total of 708 ESRD events and 650 deaths events over mean (SD) follow-up periods of 4.9 (2.9) years and 6.5 (2.5) years, respectively. Lower VDMR was associated with increased risk of ESRD prior to adjusting for kidney function (hazard ratio [HR], 1.80 per 20 pg/ng lower VDMR; 95% confidence interval [CI], 1.56–2.08), but not with adjustment for kidney function (HR, 0.94 per 20 pg/ng; 95% CI, 0.81–1.10). Lower VDMR was associated with modestly increased mortality risk, including adjustment for kidney function (HR, 1.18 per 20 pg/ng; 95% CI, 1.02–1.36). Conclusion Lower VDMR, a measure of CYP24A1-mediated vitamin D clearance, was significantly associated with all-cause mortality but not with progression to ESRD in patients with CKD.
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Serum 24,25-dihydroxyvitamin D 3 response to native vitamin D 2 and D 3 Supplementation in patients with chronic kidney disease on hemodialysis. Clin Nutr 2017; 37:1041-1045. [PMID: 28506446 DOI: 10.1016/j.clnu.2017.04.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/04/2017] [Accepted: 04/24/2017] [Indexed: 01/18/2023]
Abstract
BACKGROUND & AIMS While vitamin D deficiency is common in patients with end stage renal disease on dialysis and treatment with Vitamin D2 and Vitamin D3 is becoming increasingly common in these patients, little is known about 24,25(OH)2D3 metabolite production. Some authors report that the CYP24A1 enzyme is upregulated in CKD, but reports of low serum levels of 24,25(OH)2D3 in these patients bring this into question. Lack of substrate or increased clearance of the metabolite have been proposed as possible causes. We report serum 24,25(OH)2D3 levels from three controlled trials of Vitamin D2 and Vitamin D3 supplementation which reached adequate levels of 25(OH)D in patients with end stage renal disease on dialysis. METHODS 680 samples from three controlled trials of Vitamin D2 or Vitamin D3 supplementation in CKD Stage 5D were available for analysis. The trials used single doses of 50,000 IU Vitamin D3, or 50,000 IU Vitamin D2, or weekly doses of 10,000 IU or 20,000 IU Vitamin D3. Blood samples were drawn at baseline and frequently over the ensuing 3-4 months. Serum 25(OH)D and 24,25(OH)2D3 levels were measured using a novel, very sensitive LC-MS/MS-based method involving derivatization with DMEQ-TAD. Linear mixed effect regression models were used to compare the 3 studies and the interventions within studies over time. RESULTS The subjects given Vitamin D3 had significant increases in 25(OH)D levels. Serum 24,25(OH)2D3 levels were low at baseline in the renal patients and rose slightly with native vitamin D supplementation, but these levels were lower than reports of 24,25(OH)2D3 in healthy populations. CONCLUSIONS We conclude that the enzymatic activity of CYP24A1 is abnormal in end stage renal patients on dialysis. These trials were registered on clinicaltrials.govNCT00511225 on 8/1/2007; NCT01325610 on 1/17/2011; and NCT01675557 on 8/28/2012.
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Alshayeb H, Showkat A, Wall BM, Gyamlani GG, David V, Quarles LD. Activation of FGF-23 mediated vitamin D degradative pathways by cholecalciferol. J Clin Endocrinol Metab 2014; 99:E1830-7. [PMID: 24960544 PMCID: PMC4184071 DOI: 10.1210/jc.2014-1308] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONTEXT The optimal circulating concentration of 25(OH) vitamin D is controversial. OBJECTIVE The aim was to investigate if FGF-23 and 24,25(OH)2D can guide cholecalciferol replacement. DESIGN Oral cholecalciferol (10,000 IU weekly) administered to subjects with 25(OH)D levels < 20 ηg/mL and eGFR > 60 mL/min/1.73 m(2) (n = 25), chronic kidney disease (CKD) (n = 27), or end stage renal disease (ESRD) (n = 14). SETTING The study was conducted at the Veterans Affairs clinics. MAIN OUTCOME MEASURE Serum FGF-23, PTH, 25(OH)D, 1,25(OH)2D, 24,25(OH)2D, calcium, and phosphorous concentrations, and urinary excretion of calcium and phosphorus at baseline and after 8 weeks of treatment. RESULTS Cholecalciferol treatment increased concentrations of serum 25(OH)D by (19.3 ± 8 ηg/mL, P = .001; 12.2 ± 9 ηg/mL, P = .0001) and 24,25(OH)2D (1.14 ± 0.89 ηg/mL, P = .0024; 1.0 ± 0.72 ηg/mL P = .0002), and reduced serum PTH (-11 ± 21 pg/mL, P = .0292; -42 ± 68 pg/mL, P = .0494) in normal and CKD subjects, respectively. Cholecalciferol increased serum FGF-23 levels only in normal subjects (44 ± 57 ηg/mL, P = .01). Increments in serum 25(OH)D positively correlated with serum FGF-23 and 24,25(OH)2D and negatively correlated with PTH. In ESRD, cholecalciferol administration increased 25(OH)D by (16.6 ± 6.6 ηg/mL P ≤ .05) without changing 24,25(OH)2D, FGF-23 or PTH levels. CONCLUSION Modest elevations of serum 25(OH)D levels after cholecalciferol treatment are sufficient to induce compensatory degradative pathways in patients with sufficient renal reserves, suggesting that optimal circulating 25(OH)D levels are approximately 20 ηg/mL. In addition, catabolism of 25(OH)D may also contribute to the low circulating vitamin D levels in CKD, since elevations of FGF-23 in CKD are associated with increased 24,25(OH)2D after cholecalciferol administration.
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Affiliation(s)
- Hala Alshayeb
- University of Tennessee Health Science Center (A.S., B.M.W., L.D.Q.), Memphis, Tennessee 38103; Veterans Affairs Medical Center (B.M.W., G.G.G.), Memphis, Tennessee 38103; Marshall University (H.A.), Huntington, West Virginia 25701; and University of Miami (V.D.), Miami, Florida 33136
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Stubbs JR, Zhang S, Friedman PA, Nolin TD. Decreased conversion of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3 following cholecalciferol therapy in patients with CKD. Clin J Am Soc Nephrol 2014; 9:1965-73. [PMID: 25183657 DOI: 10.2215/cjn.03130314] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Elevated concentrations of fibroblast growth factor 23 (FGF23) are postulated to promote 25-hydroxyvitamin D (25[OH]D) insufficiency in CKD by stimulating 24-hydroxylation of this metabolite, leading to its subsequent degradation; however, prospective human studies testing this relationship are lacking. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS An open-label prospective study was conducted from October 2010 through July 2012 to compare the effect of 8 weeks of oral cholecalciferol therapy (50,000 IU twice weekly) on the production of 24,25(OH)2D3 in vitamin D-insufficient patients with CKD (n=15) and controls with normal kidney function (n=15). Vitamin D metabolites were comprehensively profiled at baseline and after treatment, along with FGF23 and other mineral metabolism parameters. RESULTS Vitamin D3 and 25(OH)D3 concentrations increased equivalently in the CKD and control groups following cholecalciferol treatment (median D3 change, 8.6 ng/ml [interquartile range, 3.9-25.6 ng/ml] for controls versus 12.6 ng/ml [6.9-41.2 ng/ml] for CKD [P=0.15]; 25(OH)D3 change, 39.2 ng/ml [30.9-47.2 ng/ml] for controls versus 39.9 ng/ml [31.5-44.1 ng/ml] for CKD [P=0.58]). Likewise, the absolute increase in 1α,25(OH)2D3 was similar between CKD participants and controls (change, 111.2 pg/ml [64.3-141.6 pg/ml] for controls versus 101.1 pg/ml [74.2-123.1 pg/ml] for CKD; P=0.38). Baseline and post-treatment 24,25(OH)2D3 concentrations were lower in the CKD group; moreover, the absolute increase in 24,25(OH)2D3 after therapy was markedly smaller in patients with CKD (change, 2.8 ng/ml [2.3-3.5 ng/ml] for controls versus 1.2 ng/ml [0.6-1.9 ng/ml] for patients with CKD; P<0.001). Furthermore, higher baseline FGF23 concentrations were associated with smaller increments in 24,25(OH)2D3 for individuals with CKD; this association was negated after adjustment for eGFR by multivariate analysis. CONCLUSIONS Patients with CKD exhibit an altered ability to increase serum 24,25(OH)2D3 after cholecalciferol therapy, suggesting decreased 24-hydroxylase activity in CKD. The observed relationship between baseline FGF23 and increments in 24,25(OH)2D3 further refutes the idea that FGF23 directly contributes to 25(OH)D insufficiency in CKD through stimulation of 24-hydroxylase activity.
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Affiliation(s)
- Jason R Stubbs
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas;
| | - Shiqin Zhang
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
| | - Peter A Friedman
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Thomas D Nolin
- Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences, and Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh Schools of Pharmacy and Medicine, Pittsburgh, Pennsylvania
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de Boer IH, Sachs MC, Chonchol M, Himmelfarb J, Hoofnagle AN, Ix JH, Kremsdorf RA, Lin YS, Mehrotra R, Robinson-Cohen C, Siscovick DS, Steffes MW, Thummel KE, Tracy RP, Wang Z, Kestenbaum B. Estimated GFR and circulating 24,25-dihydroxyvitamin D3 concentration: a participant-level analysis of 5 cohort studies and clinical trials. Am J Kidney Dis 2014; 64:187-97. [PMID: 24703961 PMCID: PMC4111986 DOI: 10.1053/j.ajkd.2014.02.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 02/04/2014] [Indexed: 12/24/2022]
Abstract
BACKGROUND Decreased glomerular filtration rate (GFR) leads to reduced production of 1,25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 (25[OH]D3). Effects of low GFR on vitamin D catabolism are less well understood. We tested associations of estimated GFR (eGFR) with the circulating concentration of 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), the most abundant product of 25(OH)D3 catabolism, across populations with a wide range of GFRs. STUDY DESIGN Cross-sectional study. SETTING & PARTICIPANTS 9,596 participants in 5 cohort studies and clinical trials: the Diabetes Control and Complications Trial (N=1,193), Multi-Ethnic Study of Atherosclerosis (N=6,470), Cardiovascular Health Study (N=932), Seattle Kidney Study (N=289), and Hemodialysis Study (N=712). PREDICTOR eGFR. OUTCOME Circulating 24,25(OH)2D3 concentration. MEASUREMENTS GFR was estimated from serum creatinine using the Chronic Kidney Disease Epidemiology Collaboration equation. Vitamin D metabolites were measured by mass spectrometry. RESULTS Circulating 24,25(OH)2D3 concentration was correlated with circulating 25(OH)D3 concentration (Pearson r range, 0.64-0.88). This correlation was weaker with lower eGFRs. Moreover, the increment in 24,25(OH)2D3 concentration associated with higher 25(OH)D3 concentration (slope) was lower with lower eGFRs: 2.06 (95% CI, 2.01-2.10), 1.77 (95% CI, 1.74-1.81), 1.55 (95% CI, 1.48-1.62), 1.17 (95% CI, 1.05-1.29), 0.92 (95% CI, 0.74-1.10), 0.61 (95% CI, 0.22-1.00), and 0.37 (95% CI, 0.35-0.39) ng/mL of 24,25(OH)2D3 per 10 ng/mL of 25(OH)D3 for eGFRs≥90, 60-89, 45-59, 30-44, 15-29, and <15 mL/min/1.73 m2 and end-stage renal disease treated with hemodialysis, respectively. As a result, at a 25(OH)D3 concentration of 20 ng/mL, mean 24,25(OH)2D3 concentrations were 2.92 (95% CI, 2.87-2.96), 2.68 (95% CI, 2.64-2.72), 2.35 (95% CI, 2.26-2.45), 1.92 (95% CI, 1.74-2.10), 1.69 (95% CI, 1.43-1.95), 1.14 (95% CI, 0.62-1.66), and 1.04 (95% CI,1.02-1.07) ng/mL for each category, respectively. This interaction was independent of other relevant clinical characteristics. Race, diabetes, urine albumin excretion, and circulating parathyroid hormone and fibroblast growth factor 23 concentrations more modestly modified the association of 24,25(OH)2D3 with 25(OH)D3. LIMITATIONS Lack of direct pharmacokinetic measurements of vitamin D catabolism. CONCLUSIONS Lower eGFR is associated strongly with reduced vitamin D catabolism, as measured by circulating 24,25(OH)2D3 concentration.
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Affiliation(s)
- Ian H de Boer
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA; Department of Epidemiology, University of Washington, Seattle, WA.
| | - Michael C Sachs
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA
| | - Michel Chonchol
- Division of Nephrology, Department of Medicine, University of Colorado, Denver, CO
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA
| | - Andrew N Hoofnagle
- Kidney Research Institute, Department of Medicine, Seattle, WA; Department of Laboratory Medicine, University of Washington, Seattle, WA
| | - Joachim H Ix
- Division of Nephrology, Department of Medicine, University of California, San Diego, San Diego, CA
| | - Robin A Kremsdorf
- Kidney Research Institute, Department of Medicine, Seattle, WA; Division of Nephrology, Department of Pediatrics, Seattle Children's Hospital, Seattle, WA
| | - Yvonne S Lin
- Department of Pharmaceutics, Department of Medicine, University of Washington, Seattle, WA
| | - Rajnish Mehrotra
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA
| | - Cassianne Robinson-Cohen
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA; Department of Epidemiology, University of Washington, Seattle, WA
| | - David S Siscovick
- Department of Epidemiology, University of Washington, Seattle, WA; Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, WA
| | - Michael W Steffes
- Department of Laboratory Medicine, University of Minnesota, Minneapolis, MN
| | - Kenneth E Thummel
- Department of Pharmaceutics, Department of Medicine, University of Washington, Seattle, WA
| | - Russell P Tracy
- Department of Laboratory Medicine, University of Vermont, Burlington, VT
| | - Zhican Wang
- Department of Pharmaceutics, Department of Medicine, University of Washington, Seattle, WA
| | - Bryan Kestenbaum
- Division of Nephrology, Department of Medicine, Seattle, WA; Kidney Research Institute, Department of Medicine, Seattle, WA; Department of Epidemiology, University of Washington, Seattle, WA
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Abstract
Vitamin D metabolism consists of both production and catabolism, which are enzymatically driven and highly regulated. Renal vitamin D metabolism requires filtration and tubular reabsorption of 25-hydroxyvitamin D and is regulated by parathyroid hormone, fibroblast growth factor-23, and 1,25-dihydroxyvitamin D. In chronic kidney disease, renal production of 1,25-dihydroxyvitamin D from 25-hydroxyvitamin D is reduced. In addition, pharmacokinetic studies and epidemiologic studies of 24,25-dihydroxyvitamin D, the most abundant product of 25-hydroxyvitamin D catabolism by CYP24A1, suggest that vitamin D catabolism also is reduced. New insights into the mechanisms and regulation of vitamin D metabolism may lead to novel approaches to assess and treat impaired vitamin D metabolism in chronic kidney disease.
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Affiliation(s)
- Cortney Bosworth
- Division of Nephrology and Kidney Research Institute, University of Washington, Seattle, WA, USA
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van den Ouweland JMW, Vogeser M, Bächer S. Vitamin D and metabolites measurement by tandem mass spectrometry. Rev Endocr Metab Disord 2013; 14:159-84. [PMID: 23539484 DOI: 10.1007/s11154-013-9241-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The prevalence of vitamin D deficiency in the general population has become a major public health problem. Vitamin D deficiency might have significant consequences not only to bone health but possibly to autoimmune-, infectious and cardiovascular disease. This has resulted in increased clinical testing for 25-hydroxyvitamin D (25(OH)D) in serum, as circulating 25(OH)D is regarded as the best indicator of adequate exposure to sunlight and dietary intake of vitamin D. There are reportedly over 50 vitamin D metabolites of which 25(OH)D and 1,25(OH)2D are well known to provide clinical information. More recently, there is increasing interest in measuring the C3-epimer of 25(OH)D, which has shown to contribute significantly to the 25(OH)D concentration, particularly in infant populations, and in 24,25(OH)2D, a major catabolite of 25(OH)D metabolism. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an analytical tool that allows the specific determination of all relevant vitamin D metabolites, with the potential of performing multiple analyte analysis in a single experimental setting, creating a vitamin D profile. This article reviews recent advances in the quantification of vitamin D metabolites using LC-MS/MS.
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Nguyen HB, Eshete B, Lau KHW, Sai A, Villarin M, Baylink D. Serum 1,25-dihydroxyvitamin D: an outcome prognosticator in human sepsis. PLoS One 2013; 8:e64348. [PMID: 23741318 PMCID: PMC3669325 DOI: 10.1371/journal.pone.0064348] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/13/2013] [Indexed: 01/08/2023] Open
Abstract
In sepsis, the vitamin D active metabolite 1,25-dihydroxyvitamin D (1,25(OH)2D) may play a crucial role by its action to produce cathelicidin and improve endothelial barrier function, such that a deficiency in 1,25(OH)2D is associated with poor outcome. To test our hypothesis, we performed analysis of stored plasma samples from a prospective observational study in 91 patients with sepsis, age of 59.1+/−2.0 years, 52.7% females, and 11.0% deaths at 30 days. Vitamin D status, including 25-hydroxyvitamin D (25(OH)D), 1,25(OH)2D, 24,25-dihydroxyvitamin D (24,25(OH)2D), and parathyroid hormone (PTH), were measured daily over 3 days after hospital admission. At baseline, 1,25(OH)2D was significantly different between survivors vs. non-survivors. But there was no significant difference in 25(OH)D, 24,25(OH)2D, and PTH. In a multivariable binomial logistic regression model, age, total calcium and 1,25(OH)2D were significant predictors of 30-day mortality. Kaplan Meier analysis showed that patients with mean 1,25(OH)2D measured over 3 days of < = 13.6 pg/mL had 57.1% 30-day survival compared to 91.7% in patients with 1,25 (OH)2D level >13.6 pg/mL (p<0.01). From repeated measures regression analysis, there was significant increase in 1,25(OH)2D for increases in 25(OH)D in both survivors and non-survivors. However, compared to survivors, the low 25(OH)D in non-survivors was insufficient to account for the larger decrease in 1,25(OH)2D, indicating a dysfunctional 1α-hydroxylase. Additionally, there was a significant negative correlation between PTH and 1,25(OH)2D in both survivors and non-survivors, suggesting a severe impairment in the effect of PTH to increase renal 1α-hydroxylase activity. In conclusion, low 1,25(OH)2D levels are associated with increased 30-day mortality in sepsis patients, likely due to impaired 25(OH)D hydroxylation and PTH insensitivity. Our data also suggest that the active metabolite 1,25(OH)2D may be an important therapeutic target in the design of sepsis clinical trials.
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Affiliation(s)
- H Bryant Nguyen
- Department of Medicine, Loma Linda University, Loma Linda, California, United States of America.
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11
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Nesterova G, Malicdan MC, Yasuda K, Sakaki T, Vilboux T, Ciccone C, Horst R, Huang Y, Golas G, Introne W, Huizing M, Adams D, Boerkoel CF, Collins MT, Gahl WA. 1,25-(OH)2D-24 Hydroxylase (CYP24A1) Deficiency as a Cause of Nephrolithiasis. Clin J Am Soc Nephrol 2013; 8:649-57. [PMID: 23293122 DOI: 10.2215/cjn.05360512] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND AND OBJECTIVES Elevated serum vitamin D with hypercalciuria can result in nephrocalcinosis and nephrolithiasis. This study evaluated the cause of excess 1,25-dihydroxycholecalciferol (1α,25(OH)2D3) in the development of those disorders in two individuals. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Two patients with elevated vitamin D levels and nephrocalcinosis or nephrolithiasis were investigated at the National Institutes of Health (NIH) Clinical Center and the NIH Undiagnosed Diseases Program, by measuring calcium, phosphate, and vitamin D metabolites, and by performing CYP24A1 mutation analysis. RESULTS Both patients exhibited hypercalciuria, hypercalcemia, low parathyroid hormone, elevated vitamin D (1α,25(OH)2D3), normal 25-OHD3, decreased 24,25(OH)2D, and undetectable activity of 1,25(OH)2D-24-hydroxylase (CYP24A1), the enzyme that inactivates 1α,25(OH)2D3. Both patients had bi-allelic mutations in CYP24A1 leading to loss of function of this enzyme. On the basis of dbSNP data, the frequency of predicted deleterious bi-allelic CYP24A1 variants in the general population is estimated to be as high as 4%-20%. CONCLUSIONS The results of this study show that 1,25(OH)2D-24-hydroxylase deficiency due to bi-allelic mutations in CYP24A1 causes elevated serum vitamin D, hypercalciuria, nephrocalcinosis, and renal stones.
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Affiliation(s)
- Galina Nesterova
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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12
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Simultaneous quantification of four vitamin D metabolites in human serum using high performance liquid chromatography tandem mass spectrometry for vitamin D profiling. Clin Biochem 2012; 45:1491-6. [DOI: 10.1016/j.clinbiochem.2012.06.030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 06/09/2012] [Accepted: 06/26/2012] [Indexed: 11/20/2022]
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13
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Assessment of 24,25(OH)2D levels does not support FGF23-mediated catabolism of vitamin D metabolites. Kidney Int 2012; 82:1061-70. [PMID: 22739976 PMCID: PMC3461248 DOI: 10.1038/ki.2012.222] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Progressive elevations of fibroblastic growth factor 23 (FGF23) in chronic kidney disease may reduce serum 25-hydroxyvitamin D (25(OH)) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) levels, via stimulation of 24-hydroxylase (Cyp24a1)-mediated catabolism of these vitamin D metabolites. To test this possibility, we measured serum concentrations of 24,25-dihydroxyvitamin D (24,25(OH)(2)D), a product of Cyp24a1 hydroxylation of 25(OH)D, in the Col4a3 knockout mouse, a model of Alport syndrome-derived chronic kidney disease, and in patients with chronic kidney disease of variable severity. There was an inverse correlation between serum FGF23 and both 25(OH)D and 1,25(OH)(2)D in the mouse model, but no significant relationship was observed in the cross-sectional patient cohort. The FGF23-dependent increase in Cyp24a1 mRNA expression in the mouse kidneys was consistent with the possibility that FGF23 induces vitamin D catabolism. There was, however, a reduction in serum 24,25(OH)(2)D levels, rather than the expected elevation, in both the mice and patients with chronic kidney disease. Low 25(OH)D and elevated FGF23 and parathyroid hormone levels were correlated with the reduced serum 24,25(OH)(2)D concentrations of these patients. Thus, we failed to find support for FGF23-mediated catabolism of vitamin D metabolites in chronic kidney disease assessed by 24,25(OH)(2)D levels.
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The serum 24,25-dihydroxyvitamin D concentration, a marker of vitamin D catabolism, is reduced in chronic kidney disease. Kidney Int 2012; 82:693-700. [PMID: 22648296 PMCID: PMC3434313 DOI: 10.1038/ki.2012.193] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chronic kidney disease is characterized, in part, as a state of decreased production of 1,25-dihydroxyvitamin D (1,25(OH)(2)D); however, this paradigm overlooks the role of vitamin D catabolism. We developed a mass spectrometric assay to quantify serum concentration of 24,25-dihydroxyvitamin D (24,25(OH)(2)D), the first metabolic product of 25-hydroxyvitamin D (25(OH)D) by CYP24A1, and determined its clinical correlates and associated outcomes among 278 participants with chronic kidney disease in the Seattle Kidney Study. For eGFRs of 60 or more, 45-59, 30-44, 15-29, and under 15 ml/min per 1.73 m(2), the mean serum 24,25(OH)(2)D concentrations significantly trended lower from 3.6, 3.2, 2.6, 2.6, to 1.7 ng/ml, respectively. Non-Hispanic black race, diabetes, albuminuria, and lower serum bicarbonate were also independently and significantly associated with lower 24,25(OH)(2)D concentrations. The 24,25(OH)(2)D concentration was more strongly correlated with that of parathyroid hormone than was 25(OH)D or 1,25(OH)(2)D. A 24,25(OH)(2)D concentration below the median was associated with increased risk of mortality in unadjusted analysis, but this was attenuated with adjustment for potential confounding variables. Thus, chronic kidney disease is a state of stagnant vitamin D metabolism characterized by decreases in both 1,25(OH)(2)D production and vitamin D catabolism.
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15
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Tebben PJ, Milliner DS, Horst RL, Harris PC, Singh RJ, Wu Y, Foreman JW, Chelminski PR, Kumar R. Hypercalcemia, hypercalciuria, and elevated calcitriol concentrations with autosomal dominant transmission due to CYP24A1 mutations: effects of ketoconazole therapy. J Clin Endocrinol Metab 2012; 97:E423-7. [PMID: 22337913 PMCID: PMC3319216 DOI: 10.1210/jc.2011-1935] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations of the CYP24A1 gene, which encodes the 1,25-dihydroxyvitamin D-24-hydroxylase cytochrome P450, Cyp24A1, are predicted to result in elevated 1,25-dihydroxyvitamin D concentrations, hypercalcemia, hypercalciuria, nephrolithiasis, and bone disease. Treatment of hypercalcemia associated with CYP24A1 gene mutations has not been described. METHODS The genetic basis of a syndrome in a 44-yr-old Caucasian male characterized by intermittent hypercalcemia, hypercalciuria, elevated serum 1,25-dihydroxyvitamin D, undetectable serum 24,25-dihydroxyvitamin D, metabolically active nephrolithiasis, and reduced bone mineral density of the lumbar spine was examined. Sequencing of the CYP24A1 gene and biochemical and genetic analysis of seven family members in three generations was carried out. Because of hypercalcemia, hypercalciuria, and metabolically active nephrolithiasis, the patient was treated with a cytochrome 3A inhibitor, ketoconazole, 200 mg orally every 8 h, for 2 months. RESULTS The sequence of the CYP24A1 gene showed two canonical splice junction mutations in the proband. Analysis of family members showed a phenotype associated one or both mutations, suggesting autosomal dominant transmission with partial penetrance of the trait. After therapy with ketoconazole, statistically significant reductions in previously elevated urinary calcium into the normal range were noted. Previously elevated serum 1,25-dihydroxyvitamin D and calcium concentrations decreased, and previously decreased PTH concentrations increased into the normal range, but the differences were not statistically significant. CONCLUSIONS In a syndrome characterized by intermittent hypercalcemia, hypercalciuria, elevated 1,25-dihydroxyvitamin D, undetectable 24,25-dihydroxyvitamin D concentrations, splice junction mutations of the CYP24A1 gene, and autosomal dominant transmission of the trait, treatment with ketoconazole is useful in reducing urinary calcium.
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16
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Ishimura E, Nishizawa Y, Inaba M, Matsumoto N, Emoto M, Kawagishi T, Shoji S, Okuno S, Kim M, Miki T, Morii H. Serum levels of 1,25-dihydroxyvitamin D, 24,25-dihydroxyvitamin D, and 25-hydroxyvitamin D in nondialyzed patients with chronic renal failure. Kidney Int 1999; 55:1019-27. [PMID: 10027939 DOI: 10.1046/j.1523-1755.1999.0550031019.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND In patients with chronic renal failure (CRF), abnormalities in vitamin D metabolism are known to be present, and several factors could contribute to the abnormalities. METHODS We measured serum levels of three vitamin D metabolites, 1,25(OH)2D, 24, 25(OH)2D and 25(OH)D, and analyzed factors affecting their levels in 76 nondialyzed patients with CRF (serum creatinine> 1.6 and < 9.0 mg/dl), 37 of whom had diabetes mellitus (DM-CRF) and 39 of whom were nondiabetic (nonDM-CRF). RESULTS Serum levels of 1,25(OH)2D were positively correlated with estimated creatinine clearance (CCr; r = 0.429; P < 0.0001), and levels of 24,25(OH)2D were weakly correlated with CCr (r = 0.252, P < 0.05); no correlation was noted for 25(OH)D. Serum levels of all three vitamin D metabolites were significantly and positively correlated with serum albumin. Although there were no significant differences in age, sex, estimated CCr, calcium and phosphate between DM-CRF and nonDM-CRF, all three vitamin D metabolites were significantly lower in DM-CRF than in nonDM-CRF. To analyze factors influencing vitamin D metabolite levels, we performed multiple regression analyses. Serum 25(OH)D levels were significantly and independently associated with serum albumin, presence of DM and serum phosphate (R2 = 0.599; P < 0.0001). 24,25(OH)2D levels were significantly and strongly associated with 25(OH)D (beta = 0.772; R2 = 0.446; P < 0.0001). Serum 1,25(OH)2D levels were significantly associated only with estimated CCr (R2 = 0. 409; P < 0.0001). CONCLUSIONS These results suggest that hypoalbuminemia and the presence of DM independently affect serum 25(OH)D levels, probably via diabetic nephropathy and poor nutritional status associated with diabetes, and that 25(OH)D is actively catalyzed to 24,25(OH)2D in CRF, probably largely via extrarenal 24-hydroxylase. Serum levels of 1,25(OH)2D were significantly affected by the degree of renal failure. Thus, this study indicates that patients with CRF, particularly those with DM, should receive supplements containing the active form of vitamin D prior to dialysis.
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Affiliation(s)
- E Ishimura
- Second Department of Internal Medicine, Osaka City University Medical School, Osaka, Japan.
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17
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Brown EM. Kidney and Bone: Physiological and Pathophysiological Relationships. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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18
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Sezai S, Hirano M, Iwase T. Osteodystrophy in liver cirrhosis: detection and treatment evaluation using 99Tcm methylene diphosphonate bone scintigraphy. Clin Radiol 1991; 43:32-8. [PMID: 1847851 DOI: 10.1016/s0009-9260(05)80351-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To investigate osteodystrophy in liver cirrhosis, 99Tcm MDP (methylene diphosphonate) bone scintigraphy was performed on 36 patients with liver cirrhosis. Abnormal lesions were detected in 17 out of 36 scans (47.2%). On the other hand, areas of increased uptake were uncommon in patients with chronic active hepatitis (1/11 cases). Plasma vitamin D3 fractions [25(OH)D3, 24.25(OH)2D3 and 1.25(OH)2D3] were decreased. Statistically significant depletion of 1.25(OH)2D3 was observed in cases with positive bone scintigraphy. 1 alpha(OH)D3 (1-2 micrograms/day) was administered for 6 months to nine patients having abnormal bone scans. Six of them showed improvement without any apparent side-effects. We conclude that hepatic cirrhotic osteodystrophy can be diagnosed positively by 99Tcm MDP bone scintigraphy and can be treated accordingly.
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Affiliation(s)
- S Sezai
- Division of Gastroenterology, Tokyo Metropolitan Police Hospital, Japan
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19
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Kaune R, Schroeder B, Harmeyer J. Binding properties of plasma vitamin D-binding protein and intestinal 1,25-dihydroxyvitamin D3 receptor in piglets with pseudo-vitamin D-deficiency rickets, type I: treatment effects with pharmacological doses of vitamin D3. Arch Biochem Biophys 1990; 282:326-32. [PMID: 2173481 DOI: 10.1016/0003-9861(90)90124-h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effective treatment of the rachitic symptoms of pseudo-vitamin D-deficiency rickets, type I (PVDRI) by massive doses of vitamin D3 was examined. For this purpose, the affinities and the maximum binding capacities (Bmax) of the plasma vitamin D-binding protein (DBP) and of the intestinal 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptor for vitamin D3, 25-hydroxyvitamin D3 (25-OHD3) and 1,25-(OH)2D3, were investigated in normal piglets and in rachitic piglets that suffered from PVDRI. The piglets were 5 to 10 weeks old and of both sexes. The Bmax of plasma DBP for 25-OHD3 was 6.77 +/- 0.45 microM for PVDRI piglets and 7.30 +/- 0.41 microM for control piglets and showed no differences between the two groups. Equilibrium association constants (Ka) of DBP for 25-OHD3 were 4.3 x 10(8) M-1 for PVDRI piglets and 4.0 x 10(8) M-1 for controls and showed also no differences between the two groups. Similarly the Ka of DBP for 1,25-(OH)2D3 was also the same for rachitic and control piglets (1.45 x 10(7) and 1.54 x 10(7) M-1, respectively). Due to the lower circulating concentration of 1,25-(OH)2D3 in the plasma of rachitic piglets compared to that of controls its free metabolite index was significantly lower in rachitic (0.42 +/- 0.05 x 10(-5)) than in control piglets (3.63 +/- 0.30 x 10(-5)). The Kd and Bmax of the intestinal nuclear receptor for 1,25-(OH)2D3 of rachitic and control piglets were 0.31 +/- 0.05 and 0.33 +/- 0.05 nM and 674 +/- 103 and 719 +/- 123 fmol/mg protein, respectively, and were also not different between the two groups of piglets. It was concluded from these observations that the rachitic symptoms of PVDRI piglets resulted solely from the lower free 1,25-(OH)2D3 concentration in plasma compared to that of normal piglets. The relative affinities of the intestinal 1,25-(OH)2D3 receptor for vitamin D3 and 25-OHD3 were also measured. It was found that 50% displacement of 1,25-(OH)2D3 from the intestinal receptor of PVDRI and control piglets required a 220,000- and 245,000-fold excess of the free concentration of vitamin D3, respectively, and a 20- to 42- and 23- to 71-fold excess of the free concentration of 25-OHD3, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R Kaune
- Department of Physiology, School of Veterinary Medicine, Hannover, FRG
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20
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Abstract
The metabolism of 25-hydroxyvitamin D3 (25-OHD3) was compared following its intracardial or gastric administration. The rats were deprived of calcium and vitamin D. A mixture of radiolabeled (0.3 microCi) and stable (2 micrograms) 25-OHD3 was given as a single dose. After 24 h the rats given the dose by gastric tube had significantly lower serum concentrations of 25-OHD3 and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] than those injected intracardially. In contrast, serum 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] was much higher in the rats given the 25-OHD3 dose by gastric tube (6.2 nmol/liter +/- 1.3 SD, n = 7) compared to the intracardial group (0.9 nmol/liter +/- 0.5, p less than 0.001). The preceding results were based on specific radioactivity of metabolites. The same findings were obtained by reanalyzing the samples using conventional competitive binding assays for 25-OHD3, 1,25-(OH)2D3, and 24,25-(OH)2D3. The results show that orally administered 25-OHD3 is partly metabolized to 24,25-(OH)2D3 presystemically.
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Affiliation(s)
- R Vieth
- Department of Clinical Biochemistry, University of Toronto, Ontario, Canada
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21
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Abstract
We develop here the hypothesis that polycystic kidneys (PCK) may maintain, to a certain extent, the ability to perform endocrine functions. We know that patients with adult polycystic kidney disease (APCKD) produce more erythropoietin and maintain a higher hematocrit than patients with other primary diseases of the kidneys. It is possible that they synthesize more 1,25 and 24,25 Vit D3 and metabolize better the parathyroid hormone and other hormones. If it is correct, they may have fewer signs of secondary hyperparathyroidism and less bone marrow fibrosis which along with increased erythropoietin production would explain the higher hematocrit.
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Affiliation(s)
- C Rotellar
- Georgetown University Hospital, Washington DC 20007
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22
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Porteous CE, Coldwell RD, Trafford DJ, Makin HL. Recent developments in the measurement of vitamin D and its metabolites in human body fluids. JOURNAL OF STEROID BIOCHEMISTRY 1987; 28:785-801. [PMID: 3320575 DOI: 10.1016/0022-4731(87)90413-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- C E Porteous
- Department of Chemical Pathology, London Hospital Medical College, England
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23
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Coldwell RD, Porteous CE, Trafford DJ, Makin HL. Gas chromatography-mass spectrometry and the measurement of vitamin D metabolites in human serum or plasma. Steroids 1987; 49:155-96. [PMID: 3331846 DOI: 10.1016/0039-128x(87)90083-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Although methods for the measurement of vitamin D metabolites continue to be developed, few have been properly validated by comparison with methods based on gas chromatography-mass spectrometry, widely accepted as being the definitive methodology. To the best of our knowledge, only three such comparisons have been carried out (14, 42, 83), all three examining HPLC assays for 25-OH-D. This lack of proper validation leads to lack of certainty as to the specificity of many assays widely used for clinical investigation. In our view there is an obvious need for the continuing development of mass fragmentographic assays for vitamin D and its metabolites, primarily for use as reference procedures for the evaluation of less rigorous methodologies. Provided standards, both labeled and unlabeled, become more widely available, development of specific mass fragmentographic assays for any metabolite of vitamin D should be possible. For metabolites where no specific binding protein or antiserum is available, mass fragmentography may be the only alternative.
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Affiliation(s)
- R D Coldwell
- Department of Chemical Pathology, London Hospital Medical College, U.K
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24
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Reichel H, Koeffler HP, Norman AW. Regulation of 25-hydroxyvitamin D3 metabolism in a human promyelocytic leukemia cell line (HL-60): 1,25-dihydroxyvitamin D3 stimulates the synthesis of 24,25-dihydroxyvitamin D3. Arch Biochem Biophys 1986; 251:222-31. [PMID: 3024572 DOI: 10.1016/0003-9861(86)90069-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The human promyelocytic leukemia cell line HL-60 undergoes macrophage-like differentiation after exposure to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the biologically active metabolite of vitamin D3. In the current study, we demonstrate that 1,25(OH)2D3 also regulates 25-hydroxyvitamin D3 [25(OH)D3] metabolism in HL-60 cells. The presence of 1,25(OH)2D3 in the culture medium of HL-60 cells stimulated the conversion of 7-10% of the substrate [25(OH)D3] to a more polar metabolite, which was identified as 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] from the elution positions on sequential HPLC systems and the sensitivity to periodate treatment. The HL-60 subclone HL-60 blast, which is unresponsive to 1,25(OH)2D3 in terms of differentiation, also responded to 1,25(OH)2D3 treatment with the production of 24,25(OH)2D3. Maximal stimulation of 24,25(OH)2D3-synthesis (approximately 7 pmol/5 X 10(6) cells) in HL-60 cells was noted with a 12-h exposure to 10(-9) M 1,25(OH)2D3. The ability of vitamin D3 metabolites other than 1,25(OH)2D3 to induce the synthesis of 24,25(OH)2D3 in HL-60 cells was, with the exception of 1 alpha-hydroxyvitamin D3, in correlation with their reported affinities for the specific 1,25(OH)2D3 receptor which is present in HL-60 cells. Treatment of HL-60 cells with phorbol diesters abolished the 1,25(OH)2D3 responsiveness, while treatment with dimethylsulfoxide and interferon gamma did not markedly alter the 25(OH)D3 metabolism of HL-60 cells. Small amounts (approximately 1% of substrate) of two 25(OH)D3 metabolites, which comigrated with 5(E)- and 5(Z)-19-nor-10-keto-25-hydroxyvitamin D3 on two HPLC solvent systems, were synthesized by HL-60 cells, independently from 1,25(OH)2D3 treatment or stage of cell differentiation. Our results indicate that 1,25(OH)2D3 influences 25(OH)D3 metabolism of HL-60 cells independently from its effects on cell differentiation.
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25
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Halloran BP, Bikle DD, Levens MJ, Castro ME, Globus RK, Holton E. Chronic 1,25-dihydroxyvitamin D3 administration in the rat reduces the serum concentration of 25-hydroxyvitamin D by increasing metabolic clearance rate. J Clin Invest 1986; 78:622-8. [PMID: 3489007 PMCID: PMC423635 DOI: 10.1172/jci112619] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] can lower the serum concentration of 25-hydroxyvitamin (25-OH-D). To determine if 1,25(OH)2D3 lowers serum 25-OH-D by increasing clearance or reducing production, we directly measured the metabolic clearance rate (MCR) of 25-OH-D in rats chronically infused with 1,25(OH)2D3. Chronic 1,25(OH)2D3 administration (0 to 75 pmol/d) reduced, in a time- and dose-dependent fashion, the serum concentrations of 25-OH-D3 and 24,25(OH)2D3 from 18 +/- 2 to 9 +/- 1 ng/ml and from 4.8 +/- 0.7 to 1.3 +/- 0.3 ng/ml, respectively, and increased sevenfold the in vitro conversion of 25-OH-D to 24,25(OH)2D3 by kidney homogenates. The reduction in serum 25-OH-D3 was completely accounted for by an increase in MCR. No change in production occurred. The influence of 1,25(OH)2D3 on serum 25-OH-D3 and 24,25(OH)2D3 was shown not to be dependent on induction of hypercalcemia. These data suggest that chronic 1,25(OH)2D3 administration lowers serum 25-OH-D by increasing the metabolic clearance of 25-OH-D3 and not by decreasing its production.
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D'Amour P, Gilbert F, Gascon-Barre M, Boutin JM, Havrankova J, Bélanger R, Matte R. Late increase in serum 1,25-dihydroxyvitamin D one month after surgery for adenomatous hyperparathyroidism. Clin Endocrinol (Oxf) 1986; 24:349-58. [PMID: 3755658 DOI: 10.1111/j.1365-2265.1986.tb01638.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This study was designed to follow the evolution of serum 1,25(OH)2D after surgery for primary hyperparathyroidism. Ten patients were studied before and for up to 85 d after removal of a single parathyroid adenoma. Blood and 24 h urine were obtained at various time points, for the measurement of serum or urinary phosphate and calcium indices. Before surgery, serum calcium (2.91 +/- 0.06 mmol/l; mean +/- SEM), parathyroid hormone (354 +/- 47 pg/ml) and 1,25(OH)2D (61.2 +/- 7.8 pg/ml) were elevated while serum phosphate (1.01 +/- 0.07 mmol/l) tended to be low. Relative hypoparathyroidism was evident for up to 5 d after surgery with the lowest value for serum parathyroid hormone (41 +/- 16 pg/ml) on day 1, serum calcium (2.12 +/- 0.06 mmol/l) on day 3 and highest value for serum phosphate (1.41 +/- 0.13 mmol/l) on day 5. As expected, serum 1,25(OH)2D levels decreased to 35.9 +/- 4.2 pg/ml 24 h after surgery. Stabilization of serum and urinary parameters to normal values was seen between day 5 and day 27; the only exception was serum 1,25(OH)2D, which increased again at day 27 to 57.6 +/- 5.0 pg/ml, a value as high as that before surgery. It was still elevated at day 50 (58.3 +/- 4.3 pg/ml), but returned towards normal values in three out of four patients (44 +/- 3.9 pg/ml) by day 80. No variation in 25(OH)D or 24,25(OH)2D was seen throughout the study. 1,25(OH)2D values could be related to serum parathyroid hormone values before surgery (r = 0.659, P less than 0.05) but not after. The secondary increase in serum 1,25(OH)2D could not be related to variations in serum calcium, phosphate, parathyroid hormone or diet. Further studies will be required to explain this phenomenon.
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KAUNE R, HARMEYER J. Die quantitative Bestimmung von Vitamin D3und seiner Metaboliten im Plasma. ACTA ACUST UNITED AC 1986. [DOI: 10.1515/bchm3.1986.367.2.1135] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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28
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Horst RL, Wovkulich PM, Baggiolini EG, Uskoković MR, Engstrom GW, Napoli JL. (23S)-1,23,25-Trihydroxyvitamin D3: its biologic activity and role in 1 alpha,25-dihydroxyvitamin D3 26,23-lactone biosynthesis. Biochemistry 1984; 23:3973-9. [PMID: 6548386 DOI: 10.1021/bi00312a026] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
(23S)-1,23,25-Trihydroxyvitamin D3 was isolated from bovine kidney homogenates incubated with 1,25-dihydroxyvitamin D3 by sequential chromatography through one Sephadex LH-20 column and three high-performance liquid chromatography systems. Ultraviolet absorption spectroscopy and mass spectrometry confirmed the structural assignment. One high-performance liquid chromatography system separated the R and S epimers of 1,23,25-trihydroxyvitamin D3 and indicated that the natural product had the S configuration. Plasma pharmacokinetic studies in rats showed that (23S)-1,23,25-trihydroxy[3H]vitamin D3 was rapidly cleared from plasma (t1/2 = 60 min). 1 alpha,25-Dihydroxy[3H]vitamin D3 26,23-lactone appeared concurrently with the disappearance of (23S)-1,23,25-trihydroxy[3H]vitamin D3. Experiments with radioinert compounds showed that 1,25-dihydroxyvitamin D3 and (23S)-1,23,25-trihydroxyvitamin D3 were efficient precursors to 1,25-dihydroxyvitamin D3 26,23-lactone both in intact and in nephrectomized rats. (25S)-1,25,26-Trihydroxyvitamin D3, however, was ineffective at raising plasma 1,25-dihydroxyvitamin D3 26,23-lactone concentrations. These results confirm the presence of extrarenal 1,25-dihydroxyvitamin D3 23(S)-hydroxylase(s) and demonstrate that C-23 hydroxylation of 1,25-dihydroxyvitamin D3 precedes C-26 hydroxylation in the formation of 1,25-dihydroxyvitamin D3 26,23-lactone. (23S)-1,23,25-Trihydroxyvitamin D3 had no intestinal calcium absorptive or bone calcium resorptive activity when dosed to vitamin D deficient rats at levels up to 500 ng. C-23 oxidation, therefore, appears to be a physiologic pathway of 1,25-(OH)2D3 metabolism and a major pathway for the deactivation of pharmacologic levels of 1,25-dihydroxyvitamin D3.
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Hummer L, Christiansen C. A sensitive and selective radioimmunoassay for serum 24,25-dihydroxycholecalciferol in man. Clin Endocrinol (Oxf) 1984; 21:71-9. [PMID: 6611226 DOI: 10.1111/j.1365-2265.1984.tb00138.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We have developed a sensitive and selective radioimmunoassay for 24,25-dihydroxycholecalciferol (24,25(OH)2D3). Antisera with a high titre and affinity to 24,25(OH)2D3 were raised in rabbits immunized with a protein conjugate of the 3-hemisuccinate derivative of 24,25(OH)2D3. Serum samples were extracted by methanol/dichloromethane and the lipid extracts purified on Sephadex LH 20 and chromatographed by single step HPLC on a straight phase silica column. The radioimmunoassay is capable of measuring 24,25(OH)2D3 in the '24,25(OH)2D complex' isolated by HPLC and containing the comigrating metabolites: 24,25(OH)2D3, 24,25(OH)2D2, 25(OH)D3-26,23 lactone and 25,26(OH)2D2. The detection limit of 2 pg/assay tube is a marked improvement, compared to the competitive protein binding assay using rachitic rat serum. Measured by the radioimmunoassay 24,25(OH)2D3 ranged from 0.05 to 1.96 ng/ml with a mean of 0.85 ng/ml in 34 healthy adults. For comparison 24,25(OH)2D, measured simultaneously by competitive protein binding with rachitic rat serum, ranged from 0.1 to 4.0 ng/ml with a mean of 1.76 ng/ml.
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Turner RT, Avioli RC, Bell NH. Extrarenal metabolism of 25-hydroxycholecalciferol in the rat: regulation by 1,25-dihydroxycholecalciferol. Calcif Tissue Int 1984; 36:274-8. [PMID: 6432292 DOI: 10.1007/bf02405330] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
To determine the role of the kidney in regulation of 25-hydroxycholecalciferol (25OHD3, metabolism, the effects of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] on 3H-25OHD3 were compared in intact and nephrectomized vitamin D-deficient rats. Sixteen hours after the intravenous administration of 3H-25OHD3, extracts of serum and pooled small intestinal mucosa were fractionated by Sephadex LH-20 column chromatography followed by high performance liquid chromatography. In intact rats, 1,25(OH)2D3 (50 ng/day i.p. for 7 days) increased mean serum 3H-24,25-dihydroxycholecalciferol [3H-24,25(OH)2D3] from 2 +/- 2-210 +/- 80 fmol/ml (mean +/- 1 SD), increased mean serum 3H-25,26-dihydroxycholecalciferol [3H-25,26(OH)2D3] from 2 +/- 2-12 +/- 6 fmol/ml and lowered mean serum 3H-1,25(OH)2D3 from 210 +/- 40-4 +/- 4 fmol/ml. Similarly, in nephrectomized animals, 1,25(OH)2D3 increased mean serum 3H-24,25-(OH)2D3 from 6 +/- 11-115 +/- 30 fmol/ml and increased mean serum 3H-25,26(OH)2D3 from 3 +/- 3-26 +/- 10 fmol/ml. Nephrectomy increased serum 3H-25(OH)D3 in untreated (from 1450 +/- 225-2675 +/- 225 fmol/ml serum) and 1,25(OH)2D3 treated rats (from 1600 +/- 175-3075 +/- 100 fmol/ml). 3H-1,25(OH)2D3 averaged 74 +/- 16% of total radioactivity in intestinal mucosa of untreated intact rats and was not detected in either the serum or intestinal mucosa of nephrectomized animals. The results suggest that in intact animals, extrarenal synthesis can account for substantial 24,25(OH)2D3 production and for most 25,26(OH)2D3 production.(ABSTRACT TRUNCATED AT 250 WORDS)
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31
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Vitamin D and Kidney Disease. Nephrology (Carlton) 1984. [DOI: 10.1007/978-1-4612-5284-9_115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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32
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Napoli JL, Pramanik BC, Royal PM, Reinhardt TA, Horst RL. Intestinal synthesis of 24-keto-1,25-dihydroxyvitamin D3. A metabolite formed in vivo with high affinity for the vitamin D cytosolic receptor. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44636-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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Horst RL, Hove K, Littledike ET, Reinhardt TA, Uskokovic MR, Partridge JJ. Plasma concentrations of 1,25-dihydroxyvitamin D, 1,24R,25-trihydroxyvitamin D3, and 2,25,26-trihydroxyvitamin D3 after their administration to dairy cows. J Dairy Sci 1983; 66:1455-60. [PMID: 6688433 DOI: 10.3168/jds.s0022-0302(83)81959-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Intramuscular administration of 1,25 (R or S),26-trihydroxyvitamin D3 to dairy cows resulted in significant elevation of 1,25-dihydroxyvitamin D3 concentration in blood plasma. The increase of 1,25-dihydroxyvitamin D3 in plasma paralleled the increase of 1,25,26-trihydroxyvitamin D3. We also found that intramuscular 1,25-dihydroxyvitamin D3 administration to dairy cows significantly elevated plasma 1,24,25-trihydroxyvitamin D3. These data suggest possible impairment of 1,25-dihydroxyvitamin D3 metabolism during the presence of pharmacologic concentrations of 1,25,26-dihydroxyvitamin D3 in plasma. In addition, the 24-hydroxylation of 1,25-dihydroxyvitamin D3 to 1,24,25-trihydroxyvitamin D3 appears to be an important route for further metabolism of 1,25-dihydroxyvitamin D3 in dairy cows.
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Hollis BW. Individual quantitation of vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 in human milk. Anal Biochem 1983; 131:211-9. [PMID: 6311049 DOI: 10.1016/0003-2697(83)90157-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Extraction, lipid-reduction, and chromatographic methods suitable for the resolution and subsequent quantitation of vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxy-vitamin D3 from human milk are described. This procedure utilizes a methanol:methylene chloride extraction, precipitation of unwanted lipids with cold methanol and ether, backwash with alkaline buffer, silica Sep-Pak preparative chromatography, normal- and reverse-phase high-performance liquid chromatography with final quantitation of the antirachitic sterols by competitive protein binding assay. The described assay was used to determine these antirachitic sterols in milk from women receiving various supplements of vitamin D or undergoing ultraviolet phototherapy.
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Horst RL, Reinhardt TA. Vitamin D metabolism in ruminants and its relevance to the periparturient cow. J Dairy Sci 1983; 66:661-78. [PMID: 6304162 DOI: 10.3168/jds.s0022-0302(83)81844-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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36
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Zerwekh JE, McPhaul JJ, Parker TF, Pak CY. Extra-renal production of 24,25-dihydroxyvitamin D in chronic renal failure during 25 hydroxyvitamin D3 therapy. Kidney Int 1983; 23:401-6. [PMID: 6601738 DOI: 10.1038/ki.1983.33] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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37
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Horst RL, Reinhardt TA, Napoli JL. 23-keto-25-hydroxyvitamin D3 and 23-keto-1,25-dihydroxyvitamin D3: two new vitamin D3 metabolites with high affinity for the 1,25-dihydroxyvitamin D3 receptor. Biochem Biophys Res Commun 1982; 107:1319-25. [PMID: 6291527 DOI: 10.1016/s0006-291x(82)80142-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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38
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23S,25-dihydroxyvitamin D3 as a circulating metabolite of vitamin D3. Its role in 25-hydroxyvitamin D3-26,23-lactone biosynthesis. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34119-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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40
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Horst RL, Pramanik BC, Reinhardt TA, Shiuey SJ, Partridge JJ, Uskoković MR, Napoli JL. Binding properties of 23S,25-dihydroxyvitamin D3: an in vivo metabolite of vitamin D3. Biochem Biophys Res Commun 1982; 106:1006-11. [PMID: 6288026 DOI: 10.1016/0006-291x(82)91811-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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41
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Lambert PW, Stern PH, Avioli RC, Brackett NC, Turner RT, Greene A, Fu IY, Bell NH. Evidence for extrarenal production of 1 alpha ,25-dihydroxyvitamin D in man. J Clin Invest 1982; 69:722-5. [PMID: 6895901 PMCID: PMC371031 DOI: 10.1172/jci110501] [Citation(s) in RCA: 111] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Recent studies provide evidence for extrarenal production of 1 alpha ,25-dihydroxyvitamin D [1 alpha ,25(OH)2D]. To investigate this possibility, serum vitamin D, 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D], and 1 alpha ,25(OH)2D were measured in eight adult anephric subjects. All were undergoing hemodialysis and three of them were receiving vitamin D, 50,000 or 100,000 U/d. Serum vitamin D was elevated in two of the patients given vitamin D and was abnormally low in the others. Mean serum 25-OHD was increased in patients given vitamin D (94.0 +/- 7.6 ng/ml) and was normal in the others (16.4 +/- 0.9 ng/ml, P less than 0.001). Mean serum 24,25(OH)2D was normal in patients given vitamin D (1.38 +/- 0.27 ng/ml) and was low in the others (0.25 +/- 0.08 ng/ml, P less than 0.001). Serum 24,25(OH)2D correlated significantly with serum 25-OHD (r = 0.848, P less than 0.01). Mean serum 1 alpha ,25(OH)2D determined by receptor assay was 5.8 +/- 1.9 pg/ml in patients who were not given vitamin D and was 14.1 +/- 0.6 in those who were given vitamin D (P less than 0.001). Serum 1 alpha ,25(OH)2D correlated significantly with serum 25-OHD (r = 0.911, P less than 0.01). Mean serum 1 alpha ,25(OH)2D, measured by bioassay, was 8.3 +/- 1.9 pg/ml in patients who were given vitamin D and was 15.9 +/- 2.4 pg/ml in those who were given vitamin D (P less than 0.05). There was a significant correlation between the values for serum 1 alpha ,25(OH)2D obtained with the two methods (r = 0.728, P less than 0.01). The results (a) provide evidence in man for extrarenal production of both 24,25(OH)2D and, by two independent assays, of 1 alpha , 25(OH)2D, and (b) indicate that serum values of the two dihydroxy metabolites of vitamin D in anephric subjects vary with the serum concentration of the precursor 25-OHD.
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Lambert PW, De Oreo PB, Fu IY, Kaetzel DM, von Ahn K, Hollis BW, Roos BA. Urinary and plasma vitamin D3 metabolites in the nephrotic syndrome. METABOLIC BONE DISEASE & RELATED RESEARCH 1982; 4:7-15. [PMID: 6289039 DOI: 10.1016/0221-8747(82)90003-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Using newly developed and established extraction, Lipidex-5000 chromatography, normal phase gradient HPLC, and ligand binding assay techniques we have directly measured plasma and urine levels of vitamin D3 and its metabolites in seven normal subjects and seven patients with nephrotic syndrome and normal renal function. Significant reductions in the plasma levels of vitamin D3, 24,25(OH)2D3, 25,26(OH)2D3, and 1,25(OH)2D3 were noted in all nephrotic patients. In conjunction with the plasma metabolite abnormalities, direct quantitative analysis of the urine in these patients revealed significant increases in nonconjugated 250HD3, 24,25(OH)2D3 and 1,25(OH)2D3. Significant correlations were noted between the plasma and/or urine metabolites and other mineral homeostatic parameters. The results indicate that the primary basis for the reductions in plasma vitamin D3 and its metabolites in the nephrotic syndrome is enhanced urinary excretion. The findings of normal serum ionized Ca and i-PTH levels in the patients with nephrosis suggest that reductions in bound and not free forms of vitamin D3 metabolites in plasma may occur in the initial stages of the nephrotic syndrome.
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Reinhardt TA, Napoli JL, Beitz DC, Littledike ET, Horst RL. 1,24,25-Trihydroxyvitamin D3: a circulating metabolite in vitamin D2-treated bovine. Arch Biochem Biophys 1982; 213:163-8. [PMID: 6277250 DOI: 10.1016/0003-9861(82)90451-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Napoli JL, Horst RL. 25,26-dihydroxyvitamin D3 is not a major intermediate in 25-hydroxyvitamin D3-26,23-lactone formation. Arch Biochem Biophys 1981; 212:754-8. [PMID: 6275800 DOI: 10.1016/0003-9861(81)90419-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Reinhardt TA, Napoli JL, Praminik B, Littledike ET, Beitz DC, Partridge JJ, Uskoković MR, Horst RL. 1 Alpha-25,26-trihydroxyvitamin D3: an in vivo and in vitro metabolite of vitamin D3. Biochemistry 1981; 20:6230-5. [PMID: 6272836 DOI: 10.1021/bi00524a050] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A new metabolite of vitamin D3 has been isolated from the plasma of vitamin D3 treated cows and has been generated from 25(S),26-dihydroxyvitamin D3 with homogenates of vitamin D deficient chick kidney. This metabolite has been identified as 1,25,26-trihydroxyvitamin D3 by comigration with synthetic 1,25(S),26-trihydroxyvitamin D3 in four chromatographic systems, ultraviolet spectroscopy, mass spectrometry, and high-pressure liquid chromatography and mass spectrometry of derivatives. 1,25(S),26-Trihydroxyvitamin D3 is one-tenth as effective as 1,25-dihydroxyvitamin D3 in binding to the chick intestinal cytosol 1,25-dihydroxyvitamin D receptor. Either 25(S),26-dihydroxyvitamin D3 or 1,25-dihydroxyvitamin D3 can serve as precursor for in vitro production of 1,25,26-trihydroxyvitamin D3 by chick kidney tissue.
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Horst RL, Littledike ET, Riley JL, Napoli JL. Quantitation of vitamin D and its metabolites and their plasma concentrations in five species of animals. Anal Biochem 1981; 116:189-203. [PMID: 6272611 DOI: 10.1016/0003-2697(81)90344-4] [Citation(s) in RCA: 119] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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47
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Barbour GL, Coburn JW, Slatopolsky E, Norman AW, Horst RL. Hypercalcemia in an anephric patient with sarcoidosis: evidence for extrarenal generation of 1,25-dihydroxyvitamin D. N Engl J Med 1981; 305:440-3. [PMID: 6894783 DOI: 10.1056/nejm198108203050807] [Citation(s) in RCA: 241] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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48
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