1
|
Mithal A, Bonjour JP, Boonen S, Burckhardt P, Degens H, El Hajj Fuleihan G, Josse R, Lips P, Morales Torres J, Rizzoli R, Yoshimura N, Wahl DA, Cooper C, Dawson-Hughes B. Impact of nutrition on muscle mass, strength, and performance in older adults. Osteoporos Int 2013; 24:1555-66. [PMID: 23247327 DOI: 10.1007/s00198-012-2236-y] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 09/20/2012] [Indexed: 12/25/2022]
Abstract
Muscle strength plays an important role in determining risk for falls, which result in fractures and other injuries. While bone loss has long been recognized as an inevitable consequence of aging, sarcopenia-the gradual loss of skeletal muscle mass and strength that occurs with advancing age-has recently received increased attention. A review of the literature was undertaken to identify nutritional factors that contribute to loss of muscle mass. The role of protein, acid-base balance, vitamin D/calcium, and other minor nutrients like B vitamins was reviewed. Muscle wasting is a multifactorial process involving intrinsic and extrinsic alterations. A loss of fast twitch fibers, glycation of proteins, and insulin resistance may play an important role in the loss of muscle strength and development of sarcopenia. Protein intake plays an integral part in muscle health and an intake of 1.0-1.2 g/kg of body weight per day is probably optimal for older adults. There is a moderate [corrected] relationship between vitamin D status and muscle strength. Chronic ingestion of acid-producing diets appears to have a negative impact on muscle performance, and decreases in vitamin B12 and folic acid intake may also impair muscle function through their action on homocysteine. An adequate nutritional intake and an optimal dietary acid-base balance are important elements of any strategy to preserve muscle mass and strength during aging.
Collapse
Affiliation(s)
- A Mithal
- Medanta Medicity, Sector 38, Gurgaon, India.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Usatii M, Rousseau L, Demers C, Petit JL, Brossard JH, Gascon-Barré M, Lavigne JR, Zahradnik RJ, Nemeth EF, D'Amour P. Parathyroid hormone fragments inhibit active hormone and hypocalcemia-induced 1,25(OH)2D synthesis. Kidney Int 2007; 72:1330-5. [PMID: 17805236 DOI: 10.1038/sj.ki.5002532] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Carboxyl (C)-terminal fragments of parathyroid hormone (PTH) oppose the calcemic, phosphaturic, and bone-resorbing effects of active hormone. To study the action of these fragments on 1,25(OH)(2)D (1,25-dihydroxyvitamin D) synthesis, we infused parathyroidectomized rats with human or rat active 1-34 or 1-84 PTH at doses selected to produce similar calcemic responses. Human active PTH influenced neither phosphate nor 1,25(OH)(2)D concentrations. However, active 1-34 rat PTH decreased phosphate to the same level as vehicle-treated rats and increased 1,25(OH)(2)D to very high levels, whereas active 1-84 PTH decreased phosphate but maintained 1,25(OH)(2)D. As the latter effect could have been due to C-terminal fragment generation during its metabolic breakdown, we infused a mixture of rat C-terminal fragments alone or with rat 1-34. The C-terminal fragments decreased 1,25(OH)(2)D and prevented hypocalcemic-induced 1,25(OH)(2)D synthesis. When infused with active rat 1-34, they lowered the 1,25(OH)(2)D level to that seen with intact rat 1-84. The C-terminal fragments did not influence either basal or rat 1-34- or 1-84-induced CYP27B1 mRNA levels, suggesting that their inhibitory effects on 1,25(OH)(2)D synthesis appears to be post-transcriptional.
Collapse
Affiliation(s)
- M Usatii
- Centre de Recherche, Centre hospitalier de l'Université de Montréal-Hôpital Saint-Luc, Montréal, Quebec, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Benit A, Allard J, Rimailho J, Fauvel J, Escourrou G, Vezzosi D, Donadille F, Bennet A, Caron P. Persistent and moderate hypercalcemia related to an ovarian clear cell adenocarcinoma: Pre- and postoperative parathyroid hormone related-peptide and 1,25-dihydroxyvitamin D3 levels. J Endocrinol Invest 2006; 29:443-9. [PMID: 16794368 DOI: 10.1007/bf03344128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To evaluate the role of PTH-related peptide (PTH-rP) and 1,25-dihyhydroxyvitamin D3 in a case of hypercalcemia related to an ovarian adenocarcinoma. DESIGN We report a case of humoral hypercalcemia in a patient aged 74 yr with a clear cell adenocarcinoma of the right ovary at an early stage of its development (stage T1aN0M0) revealed by moderate and persistent hypercalcemia (variable level between 2.7 and 3.2 mmol/l without any treatment) over six months. METHODS PTH-rP and 1,25-dihydroxyvitamin D3 were measured in blood samples taken before and after hysterectomy and bilateral salpingooophorectomy and in blood samples taken intraoperatively from the right ovarian vein and a peripheral vein. RESULTS High levels of plasma PTH-rP and 1,25-dihydroxyvitamin D3 concomitant with high serum calcium and low PTH levels were found before surgery, which was followed by normalisation of all parameters studied. A concentration gradient was found regarding plasma PTHrP (right ovarian vein 60.4 pmol/l, peripheral vein 4.5 pmol/l), not 1,25-dihydroxyvitamin D3. CONCLUSION 1) moderate and persistent hypercalcemia can be observed at an early stage of an ovarian carcinoma; 2) the gradient of PTH-rP concentration between the samples taken from the right ovarian vein and a peripheral vein provides evidence for a direct secretion of PTH-rP by the ovarian tumor; 3) the increased 1,25-dihydroxyvitamin D3 level is not related to a direct ovarian production, but is a consequence of PTH-rP secretion.
Collapse
Affiliation(s)
- A Benit
- Service d'Endocrinologie, Hôpital Rangueil, CHU Toulouse, France
| | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Räkel A, Brossard JH, Patenaude JV, Albert C, Nassif E, Cantor T, Rousseau L, D'Amour P. Overproduction of an amino-terminal form of PTH distinct from human PTH(1-84) in a case of severe primary hyperparathyroidism: influence of medical treatment and surgery. Clin Endocrinol (Oxf) 2005; 62:721-7. [PMID: 15943835 DOI: 10.1111/j.1365-2265.2005.02286.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Rare patients with severe primary hyperparathyroidism present with large parathyroid tumours, severe hypercalcaemia, very high PTH levels and osteitis fibrosa cystica. Some of these patients display a large amount of C-PTH fragments in circulation and present with a higher C-PTH/I-PTH ratio than seen in less severe cases of primary hyperparathyroidism. We wanted to determine how PTH levels and circulating PTH high-performance liquid chromatography (HPLC) profiles analysed with PTH assays having different epitopes could be affected by medical and surgical treatment in such patients. DESIGN A 55-year-old man with severe hypercalcaemia (Ca(2+): 2.01 mmol/l), very high PTH levels (CA-PTH 82.1 and T-PTH 72 pmol/l) caused by a large parathyroid tumour (7.35 g) and accompanied by significant bone involvement (alkaline phosphatase of 185 UI/l and subperiostal bone resorption of hands) was referred to us. Blood was obtained at various time points during his medical treatment, before and after surgery, to measure parameters of calcium and phosphorus metabolism, and of bone turnover. HPLC separations of circulating PTH molecular forms were performed and analysed with PTH assays having 1-4 (CA), 12-18 (T), 26-32 (E) and 65-84 (C) epitopes. RESULTS Before surgery, serum Ca2+ was nearly normalized with hydratation, intravenous (IV) pamidronate and oral vitamin D administration. Despite a decrease in Ca2+ to 1.31 mmol/l, CA-PTH and T-PTH levels decreased by half in relation to a threefold increase in basal 1,25-dihydroxyvitamin D [1,25(OH)2D] level (94 to 337 pmol/l). After this initial positive response, hypercalcaemia and elevated CA- and T-PTH levels recurred even if 1,25(OH)2D levels remained elevated. The tumour was removed surgically and proved to be poorly differentiated with nuclear atypia and mitosis. After surgery, the Ca2+ level and PTH secretion normalized. The higher CA-PTH level relative to the T-PTH level observed before surgery in this patient was related to the oversecretion of an amino-terminal (N) form of PTH recognized by PTH assays with (1-4) or (26-32) epitopes but not by the T-PTH assay with a (12-18) epitope. This molecular form represented 50% of CA-PTH measured in this patient, but only 7% in less severe cases of primary hyperparathyroidism. It was unaffected by medical therapy and disappeared after surgery. CONCLUSION The relationship between the overexpression of this N-PTH molecular form and severe primary hyperparathyroidism remains unclear. Further studies will be required in these rare patients to see whether N-PTH is a marker of less well differentiated parathyroid tumours and/or relates to the overproduction of C-PTH fragments in the presence of severe hypercalcaemia.
Collapse
Affiliation(s)
- Agnès Räkel
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CHUM), Hôpital Saint-Luc, Montréal, Québec, Canada
| | | | | | | | | | | | | | | |
Collapse
|
5
|
Gerber B, Hauser B, Reusch CE. Serum levels of 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol in dogs with hypercalcaemia. Vet Res Commun 2005; 28:669-80. [PMID: 15609867 DOI: 10.1023/b:verc.0000045954.71403.74] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1,25-Dihydroxycholecalciferol (1,25-(OH)2-D3) and 25-hydroxycholecalciferol (25-OH-D3) were measured among dogs with hypercalcaemia (total serum calcium > 3.01 mmol/L) due to various causes. All values were compared to those of healthy control dogs. Serum 1,25-(OH)]2-D3 was measured by a radioimmunoassay test and serum 25-OH-D3 was measured by a protein binding assay. 1,25-(OH)2-D3 ranged from 26 to 332 pmol/L (median 110.0) in dogs with lymphoma (n = 12); from 61 to 398 pmol/L (median 248.0) in dogs with primary hyperparathyreoidism (n = 5); from 28 to 310 pmol/L (median 88.5) in dogs with chronic renal failure (n = 10); and from 60 to 239 pmol/L (median 157.5) in control dogs (n = 24). There was no significant difference in 1,25-(OH)2-D3 among dogs with different causes of hypercalcaemia. 25-OH-D3 ranged from 64 to 291 nmol/L (median 101.5) in dogs with lymphoma; from 66 to 298 nmol/L (median 91.0) in dogs with primary hyperparathyreoidism; from 35 to 184 nmol/L (median 67.0) in dogs with chronic renal failure; and from 48 to 350 nmol/L (median 306.5) in control dogs. 25-OH-D3 was significantly lower in dogs with lymphoma, primary hyperparathyroidism and chronic renal failure than in control dogs. 1,25-(OH)2-D3 and 25-OH-D3 are not predictable in dogs with hypercalcaemia.
Collapse
Affiliation(s)
- B Gerber
- Clinic for Small Animal Internal Medicine, University of Zurich, Winterthurstrasse 260, CH-8057 Zurich, Switzerland
| | | | | |
Collapse
|
6
|
Affiliation(s)
- N H Bell
- Department of Medicine, Medical University of South Carolina, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston 29401-5799, USA
| |
Collapse
|
7
|
Affiliation(s)
- T A Guise
- Department of Medicine, University of Texas Health Science Center at San Antonio 78284-7877, USA.
| | | |
Collapse
|
8
|
Affiliation(s)
- G R Mundy
- Department of Medicine/Endocrinology, University of Texas Health Science Center, San Antonio 78284-7877, USA
| | | |
Collapse
|
9
|
Shaker JL, Brickner RC, Divgi AB, Raff H, Findling JW. Case report: renal phosphate wasting, syndrome of inappropriate antidiuretic hormone, and ectopic corticotropin production in small cell carcinoma. Am J Med Sci 1995; 310:38-41. [PMID: 7604839 DOI: 10.1097/00000441-199507000-00011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Renal phosphate wasting related to a tumor (oncogenous osteomalacia) is a rare disorder usually associated with benign mesenchymal tumors. In this article, the authors describe a man with renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone associated with small cell carcinoma. Chemotherapy markedly reduced tumor burden and was associated with normalization of renal phosphate handling and serum sodium. With recurrence, renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone developed again, with the additional complication of hypercortisolism secondary to ectopic corticotropin production. The authors report the rare occurrence of renal phosphate wasting with small cell carcinoma (5 previously reported cases) and the unique co-existence of this paraneoplastic syndrome with the syndrome of inappropriate antidiuretic hormone and ectopic corticotropin production.
Collapse
Affiliation(s)
- J L Shaker
- Department of Medicine, St. Luke's Medical Center, Milwaukee, Wisconsin, USA
| | | | | | | | | |
Collapse
|
10
|
Abstract
Alterations in vitamin D metabolism normally occur after the menopause and with aging. Increases in skeletal remodeling as a consequence of estrogen deficiency lead to increased bone resorption, suppression of serum 1,25-dihydroxy-vitamin D and intestinal absorption of calcium and increases in urinary calcium. Age-related changes in vitamin D metabolism include diminished dermal production of 7-dehydrocholesterol, the precursor of previtamin D(3), vitamin D deficiency as a consequence of inadequate intake or exposure to sunshine (individuals may be institutionalized or housebound), a decline in intestinal vitamin D receptors and diminished intestinal absorption of calcium and secondary hyperparathyroidism which leads to further bone loss. These changes also have been implicated in the pathogenesis of senile osteoporosis. Treatment with vitamin D and its analogues such as 1,25-dihydrox-yvitamin D(3 )is sometimes of value in preventing bone loss and fractures in patients with postmenopausal osteoporosis and senile osteoporosis. However, the drugs have not been approved for treatment and prevention of osteoporosis.
Collapse
Affiliation(s)
- N H Bell
- Department of Medicine, Medical University of South Carolina, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401-5779, USA
| | | |
Collapse
|
11
|
|
12
|
Ho SC, Mac Donald D, Chan C, Fan YK, Chan SS, Swaminathan R. Determinants of serum 1,25-dihydroxyvitamin D concentration in healthy premenopausal subjects. Clin Chim Acta 1994; 230:21-33. [PMID: 7850990 DOI: 10.1016/0009-8981(94)90085-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Concentrations of serum phosphate and parathyroid hormone (PTH) are well known regulators of the production of 1,25-dihydroxyvitamin D (1,25-(OH)2D) and acidosis is known to affect the serum concentration of 1,25-(OH)2D. However, the factors that play a role in the regulation of serum 1,25-(OH)2D concentration in healthy subjects have not been fully evaluated. The associations of ionised calcium, pH, serum concentration of phosphate, PTH, 25-hydroxyvitamin D (25-OHD) and serum 1,25-(OH)2D were examined in 296 healthy premenopausal women (age range 17-40 years). Calculation of partial correlation coefficients showed that serum 1,25-(OH)2D was significantly correlated with phosphate (r = -0.148, P < 0.01), pH (r = 0.221, P < 0.001) and PTH (r = 0.136. P < 0.01). Ionised calcium was not related to serum 1,25-(OH)2D. When the results were stratified according to quartiles based on serum 1,25-(OH)2D concentration, significant trends (by analysis of variance) were seen in phosphate, pH, age, albumin and 25-OHD. Stepwise multiple regression analysis showed that phosphate and pH were the major contributors of serum 1,25-(OH)2D levels. There was a small contribution from PTH and 25-OHD. The results suggest that in young healthy premenopausal women plasma phosphate and pH may be important determinants of serum 1,25-(OH)2D concentration.
Collapse
Affiliation(s)
- S C Ho
- Department of Community and Family Medicine, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin
| | | | | | | | | | | |
Collapse
|
13
|
Shaker JL, Redlin KC, Warren GV, Findling JW. Case report: hypercalcemia with inappropriate 1,25-dihydroxyvitamin D in Wegener's granulomatosis. Am J Med Sci 1994; 308:115-8. [PMID: 8042652 DOI: 10.1097/00000441-199408000-00011] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hypercalcemia associated with the extrarenal production of 1,25-dihydroxyvitamin D (1,25(OH)2D) has been reported in several disorders, most notably granulomatous diseases such as sarcoidosis. The authors describe a woman with hypercalcemia, renal insufficiency, microscopic hematuria, and anemia. The circulating 1,25(OH)2D level was higher than appropriate for the ambient conditions (renal insufficiency, suppressed intact parathyroid hormone, and hypercalcemia). A kidney biopsy was consistent with Wegener's granulomatosis, and treatment with prednisone and cyclophosphamide was associated with normalization of serum calcium levels, improved renal function, a marked decrease in serum 1,25(OH)2D levels, and increased serum intact parathyroid hormone levels. These findings are consistent with the unregulated production of 1,25(OH)2D by inflammatory cells associated with Wegener's granulomatosis.
Collapse
Affiliation(s)
- J L Shaker
- Department of Medicine, St. Luke's Medical Center, Milwaukee, Wisconsin 53215
| | | | | | | |
Collapse
|
14
|
Budayr AA, Zysset E, Jenzer A, Thiébaud D, Ammann P, Rizzoli R, Jaquet-Müller F, Bonjour JP, Gertz B, Burckhardt P. Effects of treatment of malignancy-associated hypercalcemia on serum parathyroid hormone-related protein. J Bone Miner Res 1994; 9:521-6. [PMID: 8030440 DOI: 10.1002/jbmr.5650090412] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Parathyroid hormone-related protein (PTHrP) is the primary mediator of hypercalcemia in patients with malignancy-associated hypercalcemia. We conducted this study to examine the effects of treatment with a bisphosphonate on serum PTHrP. We analyzed 41 episodes of hypercalcemia occurring in 38 patients: 22 patients received alendronate, and 16 were treated with pamidronate. At baseline, 29 patients had an increased serum PTHrP (group I) and 9 had low or undetectable levels (group II). The two groups did not differ significantly in baseline hypercalcemia (3.26 versus 3.41 mM) or the response of serum calcium to therapy. Serum calcium was normalized in 88% of group I and 70% of group II patients. Lowering of the mean calcium level was not associated with a change in the level of PTHrP in group I patients (40.2 versus 36.7 pgEq/ml) or group II patients. We also analyzed data on serum PTH and 1,25-(OH)2D in 20 of the patients. Serum PTH rose with treatment in group I patients (9.7-40.2 pg/ml, p < 0.05), as did the serum 1,25-(OH)2D (19.1-32.4 pg/ml, p < 0.001). Similarly, treatment of group II patients was associated with an increase in serum PTH (9.8-37.2 pg/ml) and serum 1,25-(OH)2D (22.9-40.2 pg/ml). The individual increases in 1,25-(OH)2D levels associated with therapy could not be predicted from the level of PTHrP or the changes in levels of serum calcium or PTH. Our data show that effective treatment of malignancy-associated hypercalcemia is not associated with a consistent change in serum levels of PTHrP. Therapy is associated with a variable increase in the serum levels of PTH and 1,25-(OH)2D.
Collapse
Affiliation(s)
- A A Budayr
- Department of Veterans Affairs Medical Center, San Francisco, California
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Affiliation(s)
- T Schilling
- Department of Internal Medicine I-Endocrinology and Metabolism, University of Heidelberg, Germany
| |
Collapse
|
16
|
Brossard JH, Garon J, Lepage R, Gascon-Barré M, D'Amour P. Inhibition of 1,25(OH)2D production by hypercalcemia in osteitis fibrosa cystica: influence on parathyroid hormone secretion and hungry bone disease. BONE AND MINERAL 1993; 23:15-26. [PMID: 8274876 DOI: 10.1016/s0169-6009(08)80087-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Primary hyperparathyroidism is usually associated with normal or elevated serum 1,25-dihydroxyvitamin D [1,25(OH)2D] levels. We report a 63-year-old patient with extreme hypercalcemia (ionized serum calcium, 2.51 mmol/l; normal range, 1.19-1.36), very high serum concentrations of intact immunoreactive parathyroid hormone (iPTH) (145 pmol/l; normal range, 1-6.8), radiological lesions of osteitis fibrosa cystica, only mildly impaired renal function (creatinine clearance, 69 ml/min/m2) and very low serum levels of 1,25(OH)2D (28.8 pmol/l; normal range, 72-120). Presurgery normalization of the calcemia with normal saline, salmon calcitonin and pamidronate caused an increase in 1,25(OH)2D serum concentration to 228.3 pmol/l. A negative correlation could be established between ionized calcium and 1,25(OH)2D levels during that period (r2 = 0.80, P < 0.04). While serum calcium decreased with treatment, serum iPTH also decreased to 48.6 pmol/l, suggesting some 1,25(OH)2D inhibition of parathyroid adenoma function. Serum alkaline phosphatase also rose from 309 to 390 units/l (normal range, 25-97), suggesting the beginning of resolution of her osteitis fibrosa cystica prior to surgery. Surgical removal of a parathyroid adenoma was associated with a decrease in serum calcium and iPTH levels. To our surprise, the hypocalcemia could be managed easily with 1500 mg of oral calcium carbonate daily, even if the hungry bone disease became more active with an increase in alkaline phosphatase to 486 units/l. This was explained by the very high levels of serum 1,25(OH)2D (> 200 pmol/l) which prevailed in the postsurgery period and were probably related to decreased bone resorption and increased bone formation. This case illustrates that normalizing serum calcium prior to surgery in patients with primary hyperparathyroidism and osteitis fibrosa cystica can be highly beneficial.
Collapse
Affiliation(s)
- J H Brossard
- Centre de Recherche Clinique André-Viallet, Hôpital Saint-Luc, Montreal, Quebec, Canada
| | | | | | | | | |
Collapse
|
17
|
Basile JN, Liel Y, Shary J, Bell NH. Increased calcium intake does not suppress circulating 1,25-dihydroxyvitamin D in normocalcemic patients with sarcoidosis. J Clin Invest 1993; 91:1396-8. [PMID: 8386185 PMCID: PMC288112 DOI: 10.1172/jci116342] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Ca absorption is regulated by 1,25(OH)2D, and serum values vary inversely with Ca intake. In sarcoidosis, 1,25(OH)2D is produced by alveolar macrophages in response to gamma-interferon, and patients may develop hypercalcemia after prolonged exposure to sunlight and increased dermal production of vitamin D3. To determine if increased Ca intake suppresses serum 1,25(OH)2D in normocalcemic patients and to identify those at risk, 17 normal subjects and 11 patients were studied on a metabolic ward for two and one-half days while receiving first 400 and then 1,000 mg/d of Ca. On the low Ca intake, serum angiotensin-converting enzyme (ACE), an index of disease activity, was higher in only three of the patients than in the controls, mean serum 1,25(OH)2D was higher in the patients, and mean serum total Ca, serum Ca++, and urinary Ca were not different in the two groups. On the higher Ca intake, mean urinary Ca increased in both groups, but mean serum 1,25(OH)2D was suppressed only in the normal subjects. Thus, 1,25(OH)2D production is abnormally regulated, indicating that (a) normocalcemic patients with sarcoidosis are at risk for developing abnormal Ca metabolism, and (b) a better index of disease activity is provided by the oral Ca suppression test than by serum ACE.
Collapse
Affiliation(s)
- J N Basile
- Department of Medicine, Medical University of South Carolina, Charleston 29425
| | | | | | | |
Collapse
|
18
|
Krapf R, Vetsch R, Vetsch W, Hulter HN. Chronic metabolic acidosis increases the serum concentration of 1,25-dihydroxyvitamin D in humans by stimulating its production rate. Critical role of acidosis-induced renal hypophosphatemia. J Clin Invest 1992; 90:2456-63. [PMID: 1469097 PMCID: PMC443402 DOI: 10.1172/jci116137] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chronic metabolic acidosis results in metabolic bone disease, calcium nephrolithiasis, and growth retardation. The pathogenesis of each of these sequelae is poorly understood in humans. We therefore investigated the effects of chronic extrarenal metabolic acidosis on the regulation of 1,25-(OH)2D, parathyroid hormone, calcium, and phosphate metabolism in normal humans. Chronic extrarenal metabolic acidosis was induced by administering two different doses of NH4Cl [2.1 (low dose) and 4.2 (high dose) mmol/kg body wt per d, respectively] to four male volunteers each during metabolic balance conditions. Plasma [HCO3-] decreased by 4.5 +/- 0.4 mmol/liter in the low dose and by 9.1 +/- 0.3 mmol/liter (P < 0.001) in the high dose group. Metabolic acidosis induced renal hypophosphatemia, which strongly correlated with the severity of acidosis (Plasma [PO4] on plasma [HCO3-]; r = 0.721, P < 0.001). Both metabolic clearance and production rates of 1,25-(OH)2D increased in both groups. In the high dose group, the percentage increase in production rate was much greater than the percentage increase in metabolic clearance rate, resulting in a significantly increased serum 1,25-(OH)2D concentration. A strong inverse correlation was observed for serum 1,25-(OH)2D concentration on both plasma [PO4] (r = -0.711, P < 0.001) and plasma [HCO3-] (r = -0.725, P < 0.001). Plasma ionized calcium concentration did not change in either group whereas intact serum parathyroid hormone concentration decreased significantly in the high dose group. In conclusion, metabolic acidosis results in graded increases in serum 1,25-(OH)2D concentration by stimulating its production rate in humans. The increased production rate is explained by acidosis-induced hypophosphatemia/cellular phosphate depletion resulting at least in part from decreased renal tubular phosphate reabsorption. The decreased serum intact parathyroid hormone levels in more severe acidosis may be the consequence of hypophosphatemia and/or increased serum 1,25-(OH)2D concentrations.
Collapse
Affiliation(s)
- R Krapf
- Department of Medicine, Insel University Hospital, Berne, Switzerland
| | | | | | | |
Collapse
|
19
|
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]
|
20
|
Shaker JL, Auger GE, Wendt PP, Findling JW. Hypercalcemia associated with dysregulation of 1,25-dihydroxyvitamin D in arthritis. J Endocrinol Invest 1992; 15:771-5. [PMID: 1491127 DOI: 10.1007/bf03347650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We describe an elderly man who presented with hypercalcemia associated with suppressed intact parathyroid hormone (PTH) levels. Despite renal insufficiency the circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) was in the upper part of the normal range. Known causes of hypercalcemia were absent and mild hypercalcemia with suppression of intact PTH persisted until after bilateral hip replacement for severe arthritis (1 year after presentation). After hip replacement the ionized calcium normalized, intact PTH normalized, and 1,25(OH)2D decreased markedly. We believe the abnormalities in mineral homeostasis were related to production of 1,25(OH)2D by inflammatory mononuclear cells associated with arthritis.
Collapse
Affiliation(s)
- J L Shaker
- Department of Medicine, St. Luke's Medical Center, Milwaukee, WI 53215
| | | | | | | |
Collapse
|
21
|
Graf W, Rastad J, Akerström G, Wide L, Ljunghall S. Dynamics of parathyroid hormone release and serum calcium regulation after surgery for primary hyperparathyroidism. World J Surg 1992; 16:625-31. [PMID: 1413832 DOI: 10.1007/bf02067339] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Analysis of 14 patients with primary hyperparathyroidism (HPT) prior to and during the first year after parathyroid surgery disclosed that the operation was associated with rapid reductions of intact serum parathyroid hormone (PTH) and total serum and ionized plasma calcium values. A decreased urinary calcium excretion, a gradual elevation of renal calcium reabsorption, a transient reduction of serum calcitriol, and a late increase in 25-hydroxycholecalciferol values were also noted. Dynamic tests of parathyroid function by EDTA infusion and an oral calcium load revealed a sigmoidal relationship between serum PTH and calcium levels, and that parathyroid surgery induced considerable changes in both the position and slope of the dose-response curve. It was also apparent that PTH release was submaximally stimulated event at periods of hypocalcemia. The findings substantiate that adjustments of PTH release to acute alterations of serum calcium occur along the prevailing dose-response relationship, while stimuli being maintained for longer periods of time induce compensatory shifts in the position and slope of this curve. It is further suggested that unknown factors with PTH-like function may participate in the calcium regulation after surgery for primary HPT.
Collapse
Affiliation(s)
- W Graf
- Department of Surgery, Akademiska sjukhuset, Uppsala, Sweden
| | | | | | | | | |
Collapse
|
22
|
Fox J. Hypocalcemia, but not PTH or hypophosphatemia, induces a rapid increase in 1,25(OH)2D3 levels in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 262:E211-5. [PMID: 1539647 DOI: 10.1152/ajpendo.1992.262.2.e211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This study determined whether acute decreases in plasma ionized calcium (Ca2+) levels regulate plasma 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] levels independent of changes in parathyroid hormone (PTH) secretion and plasma phosphate levels. Chronically catheterized rats were subjected to a hypocalcemic clamp (mean decrement of Ca2+ levels 0.38 +/- 0.04 mM), a rat PTH-(1-34) infusion, and a PTH vehicle infusion for 2 h. Plasma NH2-terminal immunoreactive PTH levels were elevated 3.2- and 8.7-fold during hypocalcemia and PTH infusion, respectively. Plasma phosphate decreased by 23 +/- 4 and 42 +/- 3% during hypocalcemia and PTH infusion, respectively. In response to hypocalcemia, plasma 1,25(OH)2D3 levels increased promptly, were significantly elevated by 15 min (56 +/- 23% increase), and continued to increase until the end of the experiment at 5 h (350 +/- 30% increase). In contrast, no changes in plasma 1,25(OH)2D3 levels occurred during the PTH infusion, but levels were elevated by 5 h, i.e., 3 h after the end of the infusion (360 +/- 20% increase). No significant changes in 25(OH)D3 or 24,25(OH)2D3 levels occurred in any protocol. Thus hypocalcemia rapidly elevates 1,25(OH)2D3 levels in rats, but the increase is not caused by elevated PTH secretion, hypophosphatemia, or elevated 25(OH)D3 levels. Furthermore, the increase in 1,25(OH)2D3 levels by hypophosphatemia does not occur rapidly. These studies show that there is a calcium-dependent mechanism that is independent of changes in PTH secretion and that results in the rapid elevation of plasma 1,25(OH)2D3 levels to counteract hypocalcemia.
Collapse
Affiliation(s)
- J Fox
- Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112
| |
Collapse
|
23
|
Strewler GJ, Nissenson RA. Hypercalcemia in malignancy. West J Med 1990; 153:635-40. [PMID: 2293469 PMCID: PMC1002641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The pathogenesis of hypercalcemia in malignancy has been enigmatic until recent years. Since the realization in 1980 that bioassays for parathyroid hormone detected a cross-reacting substance in malignancy, progress has been remarkably rapid. A parathyroid hormone-related protein was purified and identified by molecular cloning as a 141-amino acid peptide with limited homology to parathyroid hormone itself. Nonetheless, both peptides activate the parathyroid hormone receptor to produce hypercalcemia. It is now clear that the parathyroid hormone-related protein is the cause of hypercalcemia in most solid tumors, particularly squamous and renal carcinomas. New assays for the hormone as well as the related peptide have greatly simplified the differential diagnosis of hypercalcemia. At the same time, new agents for the treatment of hypercalcemia are becoming available, most notably the bisphosphonate drugs.
Collapse
Affiliation(s)
- G J Strewler
- Endocrine Unit, Veterans Administration Medical Center, San Francisco, CA 94121
| | | |
Collapse
|
24
|
Ro HK, Tembe V, Krug T, Yang PY, Bushinsky DA, Favus MJ. Acidosis inhibits 1,25-(OH)2D3 but not cAMP production in response to parathyroid hormone in the rat. J Bone Miner Res 1990; 5:273-8. [PMID: 2159208 DOI: 10.1002/jbmr.5650050311] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Parathyroid hormone (PTH) is a major activator of renal proximal tubule 25-hydroxyvitamin D3-1-hydroxylase (1-OHase). Chronic metabolic acidosis (CMA) inhibits 1-OHase and reduces circulating 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] levels in rats fed a low-Ca diet (LCD, 0.002% Ca). To examine the cellular mechanism whereby CMA inhibits 1-OHase, PTH-dependent renal 1-OHase activity and cAMP were measured in proximal tubules isolated from rats fed LCD for 14 days and made acidotic by the addition of 1.5% ammonium chloride to the drinking water. Serum 1,25-(OH)2D3 and proximal tubule 1-OHase activity and cAMP content were lower in acidotic rats. hPTH-(1-34) (10(-7) M) in vitro increased cAMP content to equivalent concentrations in tubules from rats with CMA and from nonacidotic controls; however, PTH increased 1-OHase activity only in tubules from nonacidotic animals. Although forskolin increased tubule cAMP content to equivalent levels in tubules from acidotic and nonacidotic rats, 1-OHase activity declined in tubules from nonacidotic rats and remained suppressed in acidotic tubules. The results suggest that chronic metabolic acidosis inhibits the PTH activation of 1-OHase through alteration of one or more steps in a cAMP-independent messenger system. PTH and forskolin can increase cAMP production by acidotic and nonacidotic proximal tubules; however, 1-OHase activity is not restored to normal in acidotic tubules and nonacidotic tubule 1-OHase may be inhibited.
Collapse
Affiliation(s)
- H K Ro
- Department of Medicine, University of Chicago Pritzker School of Medicine, IL 60637
| | | | | | | | | | | |
Collapse
|
25
|
Weisinger JR, Favus MJ, Langman CB, Bushinsky DA. Regulation of 1,25-dihydroxyvitamin D3 by calcium in the parathyroidectomized, parathyroid hormone-replete rat. J Bone Miner Res 1989; 4:929-35. [PMID: 2610024 DOI: 10.1002/jbmr.5650040618] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Parathyroid hormone (PTH) is a major stimulus for the renal production of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Elevated arterial blood ionized calcium ([Ca2+]) depresses serum 1,25-(OH)2D3 in nonparathyroidectomized rats even when serum PTH is maintained at high levels by infusion. However, suppression by [Ca2+] of endogenous PTH, causing the fall in 1,25-(OH)2D, cannot be excluded. To determine whether [Ca2+] regulates 1,25-(OH)2D3 in the absence of a variation in PTH, we parathyroidectomized (PTX) rats (post-PTX calcium levels less than 7.0 mg/dl), inserted arterial and venous catheters, and then replaced PTH using an osmotic pump. We varied [Ca2+] by infusing either 75 mM sodium chloride (control), 0.61 mumol/min of EGTA (EGTA), or calcium chloride at 0.61 mumol/min (low calcium) or 1.22 mumol/min (high calcium) for 24 h 5 days after surgery. Blood was then drawn from the rat through the arterial catheter. Compared with the control, [Ca2+] fell with EGTA, remained constant with the low-calcium infusion, and rose with the high-calcium infusion. 1,25-(OH)2D3 was correlated inversely with [Ca2+] in all four groups together (r = -0.635, n = 34, p less than 0.001), within the control group alone (r = -0.769, n = 11, p less than 0.002), and within the EGTA group alone (r = -0.774, n = 10, p less than 0.003). Serum phosphorus, PTH, and arterial blood pH were not different in any group, and none correlated with serum 1,25-(OH)2D3. We conclude that 1,25-(OH)2D3 levels are regulated by [Ca2+] independently of serum PTH, phosphorus, and acid-base status, all of which support the hypothesis that [Ca2+] is a principal regulator of serum 1,25-(OH)2D3 in the rat.
Collapse
|
26
|
Scharla SH, Minne HW, Oswald C, Lempert UG, Schmidt-Gayk H, Ziegler R. The hypercalcemic Walker carcinosarcoma 256 of the rat causes an increase in serum 1,25-dihydroxyvitamin D3. BONE AND MINERAL 1989; 6:155-64. [PMID: 2765706 DOI: 10.1016/0169-6009(89)90047-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have studied vitamin D metabolism in rats with the transplantable hypercalcemic Walker carcinosarcoma 256, which is a well characterized animal model for humoral hypercalcemia of malignancy. 25-Hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) concentrations were determined in blood samples obtained from parathyroidectomized (PTX) female rats at different time intervals after intramuscular tumor cell inoculation. We observed a dramatic increase in serum 1,25(OH)2D3 (280 +/- 184 vs. 98 +/- 31 pmol/l) 6 days after tumor cell injection and 4 days after the initial rise of serum calcium, whereas 25(OH)D3 tended to decrease. In a separate control experiment we compared this to the effect of exogenous parathyroid hormone in PTX rats and found similar results. In contrast, rats exhibited no change in vitamin D metabolite blood concentration after inoculation of the normocalcemic Yoshida sarcoma, which obviously does not interfere with vitamin D metabolism. We conclude that the humoral bone-resorbing agent produced by the Walker tumor cells causes elevation of serum 1,25(OH)2D3 concentration by this fulfilling an additional criterion of PTH-like activity.
Collapse
Affiliation(s)
- S H Scharla
- Department of Internal Medicine 1 (Endocrinology and Metabolism), University of Heidelberg, FRG
| | | | | | | | | | | |
Collapse
|
27
|
Dusso A, Lopez-Hilker S, Lewis-Finch J, Grooms P, Brown A, Martin K, Slatopolsky E. Metabolic clearance rate and production rate of calcitriol in uremia. Kidney Int 1989; 35:860-4. [PMID: 2709678 DOI: 10.1038/ki.1989.64] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have previously demonstrated that while both normal humans and dogs tightly control serum calcitriol levels after 25(OH)D administration, anephric humans and 5/6 nephrectomized dogs significantly increase circulating 1,25(OH)2D when supraphysiological concentrations of 25(OH)D are reached in serum. Plasma 1,25(OH)2D level is determined not only by its rate of production but also by its rate of degradation. To further characterize the mechanisms involved in the responses to 25(OH)D therapy in normal circumstances and in chronic uremia, we measured metabolic clearance rate (MCR) and production rate (PR) of 1,25(OH)2D in normal dogs and in dogs with moderate and severe renal failure, at normal and supraphysiological serum concentrations of 25(OH)D. Basal MCR in uremic dogs, either with moderate or with severe renal failure, did not differ significantly from normals (6.7 +/- 0.7, 6.8 +/- 0.4 and 6.8 +/- 0.3 ml/min, respectively). Oral 25(OH)D administration for two weeks did not affect MCR either in normal animals or in both groups of uremic dogs. 25(OH)D treatment did not affect production rates in normal dogs and in animals with moderate renal failure (with normal basal values of 1,25(OH)2D), but significantly increased 1,25(OH)2D production from 0.13 +/- 0.01 to 0.25 +/- 0.04 micrograms/day (P less than 0.05) in dogs with severe renal insufficiency. These data suggest that it is the basal level of 1,25(OH)2D which regulates the synthesis of 1,25(OH)2D in response to 25(OH)D administration in normal and uremic animals.
Collapse
Affiliation(s)
- A Dusso
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | | | | | | | | | | | | |
Collapse
|
28
|
Mosekilde L, Charles P, Lindegreen P. Determinants for serum 1,25-dihydroxycholecalciferol in primary hyperparathyroidism. BONE AND MINERAL 1989; 5:279-90. [PMID: 2720198 DOI: 10.1016/0169-6009(89)90006-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Serum levels of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 25-hydroxyvitamin D3 (25(OH)D3), C-terminal immunoreactive PTH (iPTH), calcium and phosphate, and endogenous creatinine clearance (Clcr) were measured in 34 patients with primary hyperparathyroidism. Clcr ranged from 13 to 161 ml/min (mean 72). S-iPTH was elevated in 82% of the patients and correlated positively to serum calcium (r = 0.74, P less than 0.001) and inversely to Clcr (r = -0.50, P less than 0.02). S-25(OH)D3 was reduced in 28% of the patients and depended on regular multivitamin supplementation (P less than 0.005). S-1,25(OH)2D3 was increased in 26% of the patients and decreased in 9%. It was positively correlated to S-25(OH)D3 (r = 0.39, P less than 0.05) and Clcr (r = 0.42, P less than 0.02) and inversely to serum levels of calcium (r = -0.39, P less than 0.05), phosphate (r = -0.42, P less than 0.02) and iPTH (r = -0.40, P less than 0.05). Multiple regression analysis revealed a positive correlation to 25(OH)D3 when Clcr was taken into account and to Clcr when S-25(OH)D3 was taken into account. When both variables were considered no significant partial correlations were found between S-1,25(OH)2D3 and serum calcium, phosphate and PTH, respectively. It is concluded that serum levels of 25(OH)D3 and renal function are the main determinants for S-1,25(OH)2D3 in primary hyperparathyroidism.
Collapse
Affiliation(s)
- L Mosekilde
- University Department of Endocrinology, Aarhus County Hospital, Denmark
| | | | | |
Collapse
|
29
|
Kukreja SC, York PA, Nalbantian-Brandt C, Shevrin DH, Favus MJ. Effect of hypercalcemia-producing tumor on 1,25(OH)2D3 biosynthesis in athymic mice. THE AMERICAN JOURNAL OF PHYSIOLOGY 1989; 256:E309-14. [PMID: 2919669 DOI: 10.1152/ajpendo.1989.256.2.e309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Serum 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] levels are low in patients with malignancy-associated hypercalcemia (MAH), whereas murine models of MAH have high circulating 1,25(OH)2D3. To determine the effects of a hypercalcemia-producing tumor on circulating 1,25(OH)2D3, in vitro 25-hydroxyvitamin D1-hydroxylase (1OHase) activity was measured in kidneys from BALB/c athymic mice implanted with a hypercalcemia-producing human lung tumor. Twelve days of low-phosphorus diet (LPD) in control animals lowered serum phosphorus to levels found in tumor-bearing mice fed normal phosphorus diet (NPD; 4.1 +/- 0.3 vs. 4.4 +/- 0.7 mg/dl, P = NS) and increased 1OHase activity (1.6 +/- 0.2 vs. 3.9 +/- 0.7 pmol.mg protein-1.5 min-1, NPD vs. LPD, P less than 0.05). 1OHase activity was greater in tumor-bearing animals fed NPD compared with control animals fed LPD (8.4 +/- 0.6 vs. 3.9 +/- 0.7 pmol.mg protein-1.5 min-1, P less than 0.01). High-phosphorus intake suppressed 1OHase activity in both control and tumor-bearing animals. Seven days of parathyroid hormone infusion in control animals fed NPD raised serum calcium (9.4 +/- 0.2 vs. 13.3 +/- 1.6 mg/dl, P less than 0.05) and suppressed 1OHase activity (0.25 +/- 0.02 vs. 0.02 +/- 0.002 pmol.mg protein-1.5 min-1, P less than 0.001). The inverse relationship of serum phosphorus and 1OHase activity was much steeper in the tumor-bearing animals, with greater enzyme activity at comparable levels of serum phosphorus. The present study indicates that 1) factors produced by the tumor stimulate 1OHase activity, and 2) hypophosphatemia is required for expression of enhanced enzyme activity.
Collapse
Affiliation(s)
- S C Kukreja
- Department of Medicine, Veterans Administration, Chicago, Illinois 60680
| | | | | | | | | |
Collapse
|
30
|
Rosenblatt M, Caulfield MP, Fisher JE, Horiuchi N, Mckee RL, Rodan SB, Thiede MA, Thompson DD, Seedor JG, Nutt RE. A tumor-secreted protein associated with human hypercalcemia of malignancy. Biology and molecular biology. Ann N Y Acad Sci 1988; 548:137-45. [PMID: 2854715 DOI: 10.1111/j.1749-6632.1988.tb18800.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This investigation addresses a theoretical concept of tumor pathogenesis proposed over 40 years ago, namely that malignancy-associated hypercalcemia can result from endocrine secretion by tumors of a PTH-like factor. These studies demonstrate that a fragment of hHCF alone, without added or tumor-secreted cofactors or hormones, can produce hypercalcemia and other biochemical abnormalities associated with HHM. The hypercalcemia can be generated by hHCF-(1-34)NH2 action on bone, although kidney and gut could contribute to the HHM syndrome when it occurs naturally. No other tumor-secreted peptide displays this biological profile. These studies establish one (PTH-like) mechanism by which human tumors could produce hypercalcemia. Furthermore, the finding that hHCF-(1-34)NH2 is more potent than PTH in some systems is of considerable interest for the future design of hormone analogs. A broad spectrum of biological properties of hHCF-(1-34)NH2, including production of components of the HHM syndrome, can be inhibited by a PTH antagonist. Because [Tyr-34]bPTH-(7-34)NH2 selectively and competitively occupies PTH receptors, our studies demonstrate formally that hHCF-(1-34)NH2 mediates some (and perhaps all) of its actions via receptors conventionally regarded as intended for interaction with PTH, but which actually may be present to allow for expression of bioactivity of both secreted proteins. Although some structural homology is shared by the two hormones and many contribute to interaction with receptors, the disparity in structure, especially within the 1-34 domains responsible for bioactivity in both hormones, is more pronounced. The similarity in biological profiles despite structural differences between hHCF and PTH is emphasized by the inhibitory action of [Tyr-34]bPTH-(7-34)NH2 against the tumor peptide even in the absence of much of the homologous region in the PTH antagonist. This investigation provides impetus for designing more potent antagonists, which must now be regarded more appropriately as inhibitors of both PTH and hHCF. Such antagonists may best be generated from hybrid structures of the two hormones. In any case, these studies establish a promising new approach to therapy of tumor-associated hypercalcemia.
Collapse
Affiliation(s)
- M Rosenblatt
- Department of Biological Research and Molecular Biology, Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania 19486
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
1,25-Dihydroxyvitamin D (1,25-(OH)2D) plays a crucial role in the maintenance of blood calcium and phosphorus levels and in normal skeletal mineralization. The concentration of this metabolite in the blood is, by necessity, tightly regulated. The most important stimuli for renal 1,25-(OH)2D synthesis include parathyroid hormone (PTH), its second messenger cyclic adenosine monophosphate (cAMP) and phosphate deprivation. Hypocalcemia and calcitonin, initially thought to act via stimulation of PTH release, have now been shown to directly stimulate 1-hydroxylation. Estrogens also increase 1,25-(OH)2D production, probably by upregulating renal PTH receptors. Inhibitors of the renal 25-(OH)D 1 alpha-hydroxylase include 1,25-(OH)2D itself, hypercalcemia, and phosphate loading. The PTH-vitamin D axis as modulated by the serum ionized calcium level controls adaptation to alterations in dietary calcium and sodium intake and to changes in skeletal turnover based on the level of physical activity. Although normally the renal production of 1,25-(OH)2D is tightly regulated and changes little in response to vitamin D challenge, there are certain conditions in which 1,25-(OH)2D appears to be substrate-dependent. These include hypoparathyroidism, hyperparathyroidism, vitamin D deficiency, sarcoidosis and the anephric state, conditions in which PTH is not well-modulated by alterations in serum ionized calcium or in which extrarenal synthesis of 1,25-(OH)2D occurs. In several disorders, including absorptive hypercalciuria, pseudohypoparathyroidism, hypophosphatemic rickets, and tumoral calcinosis, the regulation of the renal 1 alpha-hydroxylase appears to be altered.
Collapse
Affiliation(s)
- N A Breslau
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235
| |
Collapse
|
32
|
Bell NH, Epstein S, Shary J, Greene V, Oexmann MJ, Shaw S. Evidence of a probable role for 25-hydroxyvitamin D in the regulation of human calcium metabolism. J Bone Miner Res 1988; 3:489-95. [PMID: 2848397 DOI: 10.1002/jbmr.5650030503] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1,25-Dihydroxyvitamin D [1,25-(OH)2D] is the principal mediator of the biologic effects of vitamin D. We showed previously that obese white subjects have low serum vitamin D and 25-hydroxyvitamin D (25-OHD) with increased serum-immunoreactive parathyroid hormone (PTH) and 1,25-(OH)2D, low urinary calcium, and increased urinary cyclic adenosine 3',5'-monophosphate (cyclic AMP) compared with nonobese white individuals. To determine whether 25-OHD modulates calcium metabolism, the effects of 25-OHD3, 40-100 micrograms/day for 9 days, were compared in seven obese and seven nonobese white subjects who were between the ages of 20 and 34 years. Each of them was hospitalized on a metabolic ward and given a constant daily diet that contained 400 mg calcium, 900 mg phosphate, and 18 mEq magnesium. Whereas 25-OHD3 increased mean serum 25-OHD from 7 +/- 1 to 37 +/- 5 ng/ml (P less than 0.01) and urinary calcium from 102 +/- 18 to 146 +/- 17 mg/day (P less than 0.001) and decreased mean serum 1,25-(OH)2D from 40 +/- 2 to 28 +/- 2 pg/ml (P less than 0.01) and urinary cyclic AMP from 3.23 +/- 0.57 to 2.00 +/- 0.17 nM/dl GF (P less than 0.05), it did not change mean serum calcium, ionized calcium, phosphate, magnesium, immunoreactive PTH or urinary phosphate, or creatinine clearance in the obese subjects. In contrast, 25-OHD3 increased mean serum 25-OHD from 16 +/- 1 to 46 +/- 4 pg/ml (P less than 0.001) but did not alter mean serum 1,25-(OH)2D or urinary calcium or cyclic AMP in the nonobese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- N H Bell
- Veterans Administration Medical Center, Charleston, SC 29403
| | | | | | | | | | | |
Collapse
|
33
|
Broadus AE, Mangin M, Ikeda K, Insogna KL, Weir EC, Burtis WJ, Stewart AF. Humoral hypercalcemia of cancer. Identification of a novel parathyroid hormone-like peptide. N Engl J Med 1988; 319:556-63. [PMID: 3043221 DOI: 10.1056/nejm198809013190906] [Citation(s) in RCA: 209] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- A E Broadus
- Department of Internal Medicine, Yale University, New Haven, Conn
| | | | | | | | | | | | | |
Collapse
|
34
|
Dusso A, Lopez-Hilker S, Rapp N, Slatopolsky E. Extra-renal production of calcitriol in chronic renal failure. Kidney Int 1988; 34:368-75. [PMID: 3172645 DOI: 10.1038/ki.1988.190] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Renal 1-alpha-hydroxylase activity is tightly regulated in normal humans and intact animals. No significant changes in serum 1,25(OH)2D levels occur in response to vitamin D challenge. However, conflicting reports have appeared in the literature with regard to stimulation of 1,25(OH)2D production after 25(OH)D administration in uremia. To provide further insight into this issue, 25(OH)D at a dose of 100 micrograms every other day for two weeks followed by 50 micrograms every other day for the next two weeks was given orally to seven uremic mongrel dogs. After two weeks of 25(OH)D therapy, 1,25(OH)2D levels increased from 16.4 +/- 0.9 to 28.0 +/- 1.9 pg/ml (P less than 0.001) in parallel with a fourfold increase in 25(OH)D concentrations from a basal of 50.1 +/- 6.5 to 203.2 +/- 18.1 ng/ml. No significant changes in serum i-PTH, ICa or P were observed. Linear regression analysis of the relationship between serum concentrations of 1,25(OH)2D versus 25(OH)D, for each dog during this period, showed highly significant correlation coefficients. To evaluate the possibility that extra-renal sites contribute to the described enhanced 1,25(OH)2D net synthesis after 25(OH)D treatment, similar studies were performed in four anephric patients undergoing hemodialysis. Basal serum 1,25(OH)2D levels were 5.5 +/- 2.4 pg/ml and increased to 19.6 +/- 5.0 pg/ml after 25(OH)D administration. A significant correlation was also found for the relationship between serum levels of 1,25(OH)2D and 25(OH)D in anephrics (r = 0.72, P less than 0.001). The same therapy in four normal volunteers showed no significant changes in serum 1,25(OH)2D concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- A Dusso
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | | | | | | |
Collapse
|
35
|
Horiuchi N, Caulfield MP, Fisher JE, Goldman ME, McKee RL, Reagan JE, Levy JJ, Nutt RF, Rodan SB, Schofield TL. Similarity of synthetic peptide from human tumor to parathyroid hormone in vivo and in vitro. Science 1987; 238:1566-8. [PMID: 3685994 DOI: 10.1126/science.3685994] [Citation(s) in RCA: 248] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
One mechanism considered responsible for the hypercalcemia that frequently accompanies malignancy is secretion by the tumor of a circulating factor that alters calcium metabolism. The structure of a tumor-secreted peptide was recently determined and found to be partially homologous to parathyroid hormone (PTH). The amino-terminal 1-34 region of the factor was synthesized and evaluated biologically. In vivo it produced hypercalcemia, acted on bone and kidney, and stimulated 1,25-dihydroxy-vitamin D3 formation. In vitro it interacted with PTH receptors and, in some systems, was more potent than PTH. These studies support a long-standing hypothesis regarding pathogenesis of malignancy-associated hypercalcemia.
Collapse
Affiliation(s)
- N Horiuchi
- Regional Bone Center, Helen Hayes Hospital (New York State Department of Health), West Haverstraw 10993
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Matsumoto T, Ikeda K, Morita K, Fukumoto S, Takahashi H, Ogata E. Blood Ca2+ modulates responsiveness of renal 25(OH)D3-1 alpha-hydroxylase to PTH in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1987; 253:E503-7. [PMID: 2825531 DOI: 10.1152/ajpendo.1987.253.5.e503] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
To clarify whether extracellular Ca2+ modulates renal 25-hydroxyvitamin D3 [25(OH)D3]-1 alpha-hydroxylase, thyroparathyroidectomized rats were infused with 15 mM CaCl2, 20 mM EGTA, and/or 2.5 U/h parathyroid hormone (PTH), and blood Ca2+, serum 1,25-dihydroxyvitamin D [1,25(OH)2D], and renal 1 alpha-hydroxylase activity were determined. Rats with CaCl2, EGTA, or PTH infusion (group 1) exhibited low blood Ca2+, serum 1,25(OH)2D, and 1 alpha-hydroxylase activities. Infusion of CaCl2 alone (group 2) caused a significant increase in blood Ca2+ and a reduction in serum 1,25(OH)2D and 1 alpha-hydroxylase compared with group 1. Administration of PTH alone (group 3) markedly elevated blood Ca2+, serum 1,25(OH)2D, and 1 alpha-hydroxylase activity. When EGTA was infused along with PTH (group 4), blood Ca2+ was significantly reduced compared with group 3, and serum 1,25(OH)2D and renal 1 alpha-hydroxylase were further elevated. In contrast, when CaCl2 was infused with PTH (group 5), blood Ca2+ was higher than that in group 3, and serum 1,25(OH)2D and 1 alpha-hydroxylase activities were significantly reduced compared with group 3. No significant difference in serum inorganic phosphate or urinary cAMP excretion was observed by CaCl2 or EGTA infusion in both PTH-treated and nontreated rats. These results demonstrate that extracellular Ca2+ modulates the responsiveness of renal 1 alpha-hydroxylase to PTH as well as the base-line activity of the enzyme in the absence of PTH. These effects of extracellular Ca2+ on renal 1 alpha-hydroxylase may serve to offer an efficient way of regulating 1,25(OH)2D production and serum 1,25(OH)2D concentration by altering the responsiveness of 1 alpha-hydroxylase to PTH and possibly other stimulations depending on the demand for Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- T Matsumoto
- Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan
| | | | | | | | | | | |
Collapse
|
37
|
Patron P, Gardin JP, Paillard M. Renal mass and reserve of vitamin D: determinants in primary hyperparathyroidism. Kidney Int 1987; 31:1174-80. [PMID: 3599657 DOI: 10.1038/ki.1987.125] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We studied circulating 1,25(OH)2D3 and its determinants in 102 patients with primary hyperparathyroidism (PHPT), 33 of them with recurrent renal stones, 60 with non-specific symptoms, and nine with overt bone disease. Means for serum 1,25(OH)2D3 and intestinal absorption of calcium were abnormally high in the renal stone group, slightly elevated in the non-specific group, and low-normal in the bone disease group. In the whole population of patients, we found a positive correlation between circulating 1,25(OH)2D3 and creatinine clearance (taken as an index of the functional renal mass). Negative correlations were observed between 1,25(OH)2D3 and age, and between creatinine clearance and age, the latter being not different from that observed in a normal large population. In the renal stone group, means for the determinants of the renal 1 alpha hydroxylase activity, that is, PTH activity expressed as nephrogenous cyclic AMP (NcAMP), serum phosphate and calcium were identical to those of the group with non-specific symptoms. However means for age were lower and functional renal mass significantly higher in the renal stone group, which may account for the higher value of circulating 1,25(OH)2D3. In the bone disease group, means for age, renal mass and serum calcium were identical to those of the group with non-specific symptoms, and NcAMP was far higher and hypophosphatemia more marked, which may not account for the lower value of circulating 1,25(OH)2D3. However, in the bone disease group, serum 25(OH)D was abnormally low, which may limit the renal production of 1,25(OH)2D3 and explain the low-normal circulating values.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
|
38
|
Klein KB, Orwoll ES, Lieberman DA, Meier DE, McClung MR, Parfitt AM. Metabolic bone disease in asymptomatic men after partial gastrectomy with Billroth II anastomosis. Gastroenterology 1987; 92:608-16. [PMID: 3817384 DOI: 10.1016/0016-5085(87)90008-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We sought to determine whether gastric surgery might be associated with metabolic bone disease in a well-characterized population, and if so to explore its etiology. Sixteen asymptomatic middle-aged men who had had partial gastrectomy with Billroth II anastomosis but no other risk factors for metabolic bone disease were compared with unoperated healthy controls. Studies included a dietary survey, biochemical tests of bone and mineral metabolism, radiographs of the spine, determinations of bone mineral content, and bone histomorphometry. The gastric surgery subjects exhibited frequent vertebral fractures and an unusual constellation of bone abnormalities characterized by decreased bone mineral content and hyperosteoidosis without evidence of osteomalacia. Although serum immunoreactive parathyroid hormone and 25-hydroxyvitamin D levels were not different, 1,25-dihydroxyvitamin D levels were significantly higher (p = 0.037), and 24,25-dihydroxyvitamin D levels were significantly lower (p less than 0.0001) in subjects than in controls. Partial gastrectomy with Billroth II anastomosis may be associated with asymptomatic but clinically important metabolic bone disease. The pathophysiology is uncertain, but appears to involve alterations in vitamin D metabolism.
Collapse
|
39
|
Abstract
The hypercalcemia of malignancy is mediated by complex and heterogeneous mechanisms. Once thought of as a simple paraneoplastic syndrome mediated by the effects of tumor production of PTH, it is now clear that multiple mechanisms are involved and that these mechanisms involve abnormalities in calcium transport in bone, kidney, and gut. Calcium homeostasis in normal individuals is complex and tightly regulated. Although much has been learned over the last 20 years about the effects of individual hormones on target organs, much remains to be understood about how these hormonal systems interact to control extracellular fluid calcium. Future studies on disturbances in calcium homeostasis, such as that occurring in association with malignant disease, should do much to clarify how these complex hormonal mechanisms function in the normal individual.
Collapse
|