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Vitamin D Status and Indices of Mineral Homeostasis in the Population: Differences Between 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D. Nutrients 2019; 11:nu11081777. [PMID: 31374914 PMCID: PMC6722609 DOI: 10.3390/nu11081777] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/23/2019] [Accepted: 07/31/2019] [Indexed: 12/31/2022] Open
Abstract
Opinions are conflicting about the epidemiology of vitamin D deficiency. This population-based study investigated cross-sectionally the associations of 25-hydroxyvitamin D (calcidiol) and 1,25-dihydroxyvitamin D (calcitriol) with indices of mineral homeostasis. Study cohort consisted of 979 persons of the Moli-Sani study, both sexes, ages ≥35 years. Data collection included serum calcidiol by different assays, serum calcitriol, serum parathyroid hormone, serum and urine calcium, and phosphorus. Prevalence of mild-to-moderate calcidiol deficiency (10–19 ng/mL) was 36.4% and did not associate with hypocalcemia or hyperparathyroidism. Prevalence of severe calcidiol deficiency (<10 ng/mL) was 16.8% and associated with hyperparathyroidism only (odds ratio = 8.81, 95% confidence interval = 2.4/32.9). Prevalence of calcitriol deficiency (<18 pg/mL) was 3.1% and associated with hypocalcemia (29.1, 7.4/114.5) but not hyperparathyroidism. In ANOVA along concentration strata, lower calcidiol associated with higher parathyroid hormone only (p < 0.001). Lower calcitriol associated with lower serum and urine calcium (p < 0.001) but not with parathyroid hormone. Calcidiol findings were consistent with different calcidiol assays. In the population, mild-to-moderate calcidiol deficiency did not associate with abnormal mineral homeostasis. Severe calcidiol deficiency and calcitriol deficiency associated with different disorders: lower calcidiol associated with hyperparathyroidism whereas lower calcitriol associated with hypocalcemia and low urine calcium.
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Lu CL, Yeih DF, Hou YC, Jow GM, Li ZY, Liu WC, Zheng CM, Lin YF, Shyu JF, Chen R, Huang CY, Lu KC. The Emerging Role of Nutritional Vitamin D in Secondary Hyperparathyroidism in CKD. Nutrients 2018; 10:nu10121890. [PMID: 30513912 PMCID: PMC6316278 DOI: 10.3390/nu10121890] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 12/18/2022] Open
Abstract
In chronic kidney disease (CKD), hyperphosphatemia induces fibroblast growth factor-23 (FGF-23) expression that disturbs renal 1,25-dihydroxy vitamin D (1,25D) synthesis; thereby increasing parathyroid hormone (PTH) production. FGF-23 acts on the parathyroid gland (PTG) to increase 1α-hydroxylase activity and results in increase intra-gland 1,25D production that attenuates PTH secretion efficiently if sufficient 25D are available. Interesting, calcimimetics can further increase PTG 1α-hydroxylase activity that emphasizes the demand for nutritional vitamin D (NVD) under high PTH status. In addition, the changes in hydroxylase enzyme activity highlight the greater parathyroid 25-hydroxyvitmain D (25D) requirement in secondary hyperparathyroidism (SHPT); the higher proportion of oxyphil cells as hyperplastic parathyroid progression; lower cytosolic vitamin D binding protein (DBP) content in the oxyphil cell; and calcitriol promote vitamin D degradation are all possible reasons supports nutritional vitamin D (NVD; e.g., Cholecalciferol) supplement is crucial in SHPT. Clinically, NVD can effectively restore serum 25D concentration and prevent the further increase in PTH level. Therefore, NVD might have the benefit of alleviating the development of SHPT in early CKD and further lowering PTH in moderate to severe SHPT in dialysis patients.
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Affiliation(s)
- Chien-Lin Lu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Dong-Feng Yeih
- Division of Cardiology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Yi-Chou Hou
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Cardinal-Tien Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 23155, Taiwan.
| | - Guey-Mei Jow
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Zong-Yu Li
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Wen-Chih Liu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung City 433, Taiwan.
| | - Cai-Mei Zheng
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, New Taipei City 235, Taiwan.
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11103, Taiwan.
| | - Yuh-Feng Lin
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, New Taipei City 235, Taiwan.
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11103, Taiwan.
| | - Jia-Fwu Shyu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Department of Biology and Anatomy, National Defense Medical Center, Taipei 114, Taiwan.
| | - Remy Chen
- Kidney Dialysis Center, Kamifukuoka General Hospital, Saitama 356, Japan.
| | - Chung-Yu Huang
- Department of Medicine, Show-Chwan Memorial Hospital, Changhua 50008, Taiwan.
| | - Kuo-Cheng Lu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
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Tsuprykov O, Chen X, Hocher CF, Skoblo R, Hocher B. Why should we measure free 25(OH) vitamin D? J Steroid Biochem Mol Biol 2018; 180:87-104. [PMID: 29217467 DOI: 10.1016/j.jsbmb.2017.11.014] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 11/21/2022]
Abstract
Vitamin D, either in its D2 or D3 form, is essential for normal human development during intrauterine life, kidney function and bone health. Vitamin D deficiency has also been linked to cancer development and some autoimmune diseases. Given this huge impact of vitamin D on human health, it is important for daily clinical practice and clinical research to have reliable tools to judge on the vitamin D status. The major circulating form of vitamin D is 25-hydroxyvitamin D (25(OH)D), although it is not the most active metabolite, the concentrations of total 25-hydroxyvitamin D in the serum are currently routinely used in clinical practice to assess vitamin D status. In the circulation, vitamin D - like other steroid hormones - is bound tightly to a special carrier - vitamin D-binding protein (DBP). Smaller amounts are bound to blood proteins - albumin and lipoproteins. Only very tiny amounts of the total vitamin D are free and potentially biologically active. Currently used vitamin D assays do not distinguish between the three forms of vitamin D - DBP-bound vitamin D, albumin-bound vitamin D and free, biologically active vitamin D. Diseases or conditions that affect the synthesis of DBP or albumin thus have a huge impact on the amount of circulating total vitamin D. DBP and albumin are synthesized in the liver, hence all patients with an impairment of liver function have alterations in their total vitamin D blood concentrations, while free vitamin D levels remain mostly constant. Sex steroids, in particular estrogens, stimulate the synthesis of DBP. This explains why total vitamin D concentrations are higher during pregnancy as compared to non-pregnant women, while the concentrations of free vitamin D remain similar in both groups of women. The vitamin D-DBP as well as vitamin D-albumin complexes are filtered through the glomeruli and re-uptaken by megalin in the proximal tubule. Therefore, all acute and chronic kidney diseases that are characterized by a tubular damage, are associated with a loss of vitamin D-DBP complexes in the urine. Finally, the gene encoding DBP protein is highly polymorphic in different human racial groups. In the current review, we will discuss how liver function, estrogens, kidney function and the genetic background might influence total circulating vitamin D levels and will discuss what vitamin D metabolite is more appropriate to measure under these conditions: free vitamin D or total vitamin D.
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Affiliation(s)
- Oleg Tsuprykov
- IFLB, Institute for Laboratory Medicine, Berlin, Berlin, Germany; Institute of Nutritional Sciences, University of Potsdam, Potsdam, Germany
| | - Xin Chen
- Departments of Embryology and Nephrology, The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Carl-Friedrich Hocher
- Departments of Embryology and Nephrology, The First Affiliated Hospital, Jinan University, Guangzhou, China; First Medical Faculty, Charles University of Prague, Prague, Czech Republic
| | - Roman Skoblo
- IFLB, Institute for Laboratory Medicine, Berlin, Berlin, Germany
| | - Berthold Hocher
- Institute of Nutritional Sciences, University of Potsdam, Potsdam, Germany; Departments of Embryology and Nephrology, The First Affiliated Hospital, Jinan University, Guangzhou, China.
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