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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review considers the most recent developments concerning the metabolism and homeostasis of calcium and phosphorus. The kinetics of the distribution of calcium, theories of calculus formation, hypercalcemia and hypocalcemia are discussed, as well as the role of parathyroid hormone, thyrocalcitonin and 1,25 dihydroxy Vitamin D(3) in maintaining calcium levels and skeletal integrity. In addition, the role of calcium in enzyme activation and inhibition, muscle and nerve function, and intracellular metabolism are considered.
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PMID:Recent advances in calcium and phosphorus metabolism. 16

Comparison of the mechanism of action Vitamin D3 and 1 alpha-OH D3 under conditions of experimental hypercalcemia. Acta Physiol. Pol. 1979, 30 (2): 313--318. The hypercalcemic effect of supraphysiological doses of Vitamin D and 1 alpha-OH D3 were compared applying an animal model. Changes in serum calcium of animals with normal dietary calcium supplementation and those under conditions of calcium depletion were analyzed. Dietary calcium is necessary for the hypercalcemic effect of Vitamin D, whereas in case of 1 alpha-OH D3 calcium is mobilized not only from the dietary but also from some other sources. The analysis of the hypercalcemia kinetics in the Vitamin D and 1 alpha-OH D3 treated animals indicated that the kidney 1 hydroxylase of 25 hydroxycholecalciferol is an important step in the hypercalcemia preventing mechanism.
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PMID:Comparison of the mechanism of action of vitamin D3 and 1 alpha-OH D3 under conditions of experimental hypercalcemia. 22 75

Single administration of 0.25 microgram of sunthetic Ialpha-hydroxycholecalciferol (IalphaOHD3) into nephrectomized rats, maintained at D-avitaminous diet, improved the active transport of calcium ions against the concentration gradient in small intestine of these animals, whereas ergocalciferol was biologically inactive under the same conditions. Administration of IalphaOHD3 during 5 days at a dose 0.025 microgram normalized calcium content in blood serum of rats with D-avitaminosis, Increased doses of IalphaOHD3, administered into intact animals, caused transient hyperphosphatemia, hypercalcemia, calcinosis of internal tissues (kidney heart, aorta) as well as death of some animals. IalphaOHD3 exceeded 400-fold the hypercalcemic and calcinose effects of ergocalciferol. LD50 for IalphaOHD3 was equal to 100 microgram/kg, if it was administered during 5 days per os. Tissue calcinosis was developed after administration of a daily dose 10 microgram/kg, moderate hypercalcemia was caused by a daily dose 1 microgram/kg or 0.25 microgram per an animal; this amount is only 10-fold higher as compared with the physiologic requirement. Ergocalciferol caused hypercalcemia and metastatic calcification only at a dose 4000 microgram/kg. Clinical use of IalphaOHD3 at doses, exceeding the physiologic requirements, has to be prohibited due to high activity of the preparation and to toxicity of its increased doses.
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PMID:[Comparative study of the biological activity and toxic effect of 1alpha-hydroxycholecalciferol and ergocalciferol in rats]. 30 16

Mean plasma 1(alpha),25-dihydroxyvitamin D[1(alpha),25(OH)(2)D] was significantly increased and serum parathyroid hormone was suppressed in three patients with sarcoidosis and hypercalcemia. Prednisone lowered the mean plasma 1(alpha),25(OH)(2)D to normal range and corrected the hypercalcemia. To elucidate the mechanism for the increased sensitivity to vitamin D in this disorder, the effects of orally-administered vitamin D(2) were determined in seven normal subjects, four patients with sarcoidosis and normal calcium metabolism and three patients with sarcoidosis and a history of hypercalcemia who were normocalcemic when studied. Serum and urinary calcium, serum 25-hydroxyvitamin D (25-OHD), plasma 1(alpha),25(OH)(2)D and, in some studies, calcium balance were measured. Vitamin D(2), 250 mug a day for 12 d, produced little, if any, change in mean plasma 1(alpha),25(OH)(2)D and in urinary calcium in the normals and in the patients with normal calcium metabolism. In contrast, vitamin D(2) produced increases in plasma 1(alpha),25(OH)(2)D from concentrations which were within the normal range (20-55 pg/ml) to abnormal values and increased urinary calcium in two patients with abnormal calcium metabolism. In an abbreviated study in the third patient, vitamin D(2), 250 mug a day for 4 d, also increased plasma 1(alpha),25(OH)(2)D abnormally from a normal value. There was a highly significant correlation between plasma 1(alpha),25(OH)(2)D and urinary calcium. Serum 25-OHD and serum calcium remained within the normal range in all subjects and patients. These findings provide evidence that the defect in calcium metabolism in sarcoidosis probably results from impaired regulation of the production and(or) degradation of 1(alpha),25(OH)(2)D. Prednisone may act to correct the abnormal calcium metabolism by reducing circulating 1(alpha),25(OH)(2)D.
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PMID:Evidence that increased circulating 1 alpha, 25-dihydroxyvitamin D is the probable cause for abnormal calcium metabolism in sarcoidosis. 31 11

Maximal tubular phosphate reabsorption capacity corrected for changes in glomerular filtration rate (TmP/GFR) was taken as a measure of renal phosphate handling in patients with good and stable functioning kidney allografts. TmP/GFR values were within the normal range in only one-fifth of the patients. Eighty per cent had an abnormally low renal phosphate threshold concentration. Persistent hyperparathyroidism was the causative factor of this diminished tubular reabsorption in less than half of these patients, the majority of them showing an iPTH independent phosphate leak. Although glucocorticoids, azathioprine and tubular damage of the graft in the perioperative phase may contribute to this iPTH independent phosphate wasting, no single causative factor could be identified. Cases with hypophosphataemia should be treated in order to avoid symptoms of phosphate depletion. Active Vitamin D metabolites would be the therapy of choice by suppressing the parathyroid glands ("chemical PTX") and by directly enhancing tubular phosphate reabsorption. In persistent hyperpathyroidism with hypercalcaemia, surgical parathyroidectomy must be considered. Therapy with phosphate salts is only symptomatic and should be used only as an adjunct.
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PMID:Handling of phosphate by the transplanted kidney. 39 23

Case report of a female neonate with hypocalcemia and spasms. The cause was parathyroid insufficiency due to hyperparathroidism of the mother. The hypocalcemia was treated with a massive dose of Vitamin D; this led to a sharp rise of 25-OH-vitamin D levels in serum. The mother had kidney stones. There was hypercalcemia and a raised parathormone level. Diagnosis was confirmed by surgery. An adenoma weighing 7 g was removed.
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PMID:[Neonatal hypocalcemia in hyperparathyroidism of the mother (author's transl)]. 55 75

We describe a boy who presented at 4 years of age with radiological hyperparathyroidism, osteosclerosis, and necrosis of the femoral heads. Plasma biochemistry was normal but the parathyroid hormone (PTH) level was very high. He was deaf and had an unusual facies but did not have the phenotype of Albright's hereditary osteodystrophy. Plasma and urine cyclic AMP reponses to bovine PTH were markedly subnormal. Vitamin D produced sustained hypercalcaemia and a fall in plasma phosphorus. After four hyperplastic parathyroid glands were removed he became hypocalcaemic and plasma phosphorus rose. After operation he remained unresponsive to exogenous PTH; We suggest that he had a form of pseudohypoparathyroidism without the phenotype of Albright's hereditary osteodystrophy and with some residual skeletal and renal responsiveness to PTH.
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PMID:Normocalcaemic pseudohypoparathyroidism with unusual phenotype. 64 42

Various hormones have been implicated in the genesis of hypercalcemia in patients with malignancy. Ectopic secretion of PTH by tumor has been documented in only a few patients; rather, elevated levels of circulating iPTH have been presumed to reflect tumor production of hormone in most patients. Small fragments of PTH, as well as polypeptides larger than native PTH, have been described; their biological roles are unclear. The pattern of immunoreactivity, however, has been used to differentiate patients with ectopic hyperparathyroidism from patients with concomitant primary hyperparathyroidism. Vitamin D-like sterols produced by breast cancer seldom reach plasma levels necessary for physiological effects. Members of the prostaglandin family have been proposed to induce hypercalcemia through osteoclast activation or alteration of the immune system and also to affect the frequency of bone metastases. At present, no direct evidence is available to prove a direct role for these effects and prostaglandins are most useful as possible indicators of disease activity.
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PMID:Mechanisms of hypercalcemia in malignancy. 65 92

1. Hypo- and hypercalcemia can be explained as derangements of the calcium homeostasis. Hypocalcemic tetany usually alarming the patient tremendously is, at least in adults, rarely life-threatening. Hypercalcemia leads in 30% of the cases to clinical symptoms which may inadvertedly pass into a state of hypercalcemic crisis. This latter requires an often difficult emergency treatment. 2. Hypocalcemic tetany may be reversed by administering calcium i.v. or, in severe cases, by a calcium infusion. Only rarely are magnesium supplements necessary to let the tetany disappear. Vitamin D or dihydrotachysterol (DHT) do not correct hypocalcemia immediately, since their effects may be delayed up to 15-25 days. In order to normalize the serum calcium permanently, vitamin D or DHT treatment should be instituted as rarely as possible. 3. Initially, hypercalcemic crisis is best treated by forced intravenous fluid administration with normal saline (and furosemide) in combination with high doses of prednisone. Fluid-, sodium- and potassium balances ought to be checked during this type of treatment. A first evaluation of the effectiveness of these measures is recommended after 24 hours: treatment is continued in patients who respond favorably, while subjects who do not show a significant decrease of the serum calcium may either be given a phosphate infusion or mithramycine as a bolus. Calcitonin appears to be useful only to start treatment before institution of a phosphate infusion.
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PMID:[Hypo and hypercalcemia as an emergency]. 110 94

Thirty two specimens of Rana tigrina were divided into four equal groups : group I = controls; group II = injected with Vitamin D2 and placed in a 0.8% aqueous solution of CaCl2; group III = injected with Vitamin D2 and kept in tap water; group IV = placed only in a 0.8% CaCl2 solution. The experimental specimens exhibited varying degrees of hyperactivity of their ultimobranchial gland. Specimens from all the groups were X-rayed. The experimental ones showed different intensity of calcium deposit in their paravertebral lime sacs. The results indicate that prolonged challenge of high calcium induces hyperactivity of the ultimobranchial gland to produce larger quantity of calcitonin, to counteract the experimental hypercalcemia.
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PMID:Effect of a calcium rich environment on the ultimobranchial gland of Rana tigrina. 123 21


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