Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Normal and abnormal regulation of 1,25-(OH)2D synthesis. 306 16

The "enteque seco" is a disease of calcinosis, i.e., pathological deposition of calcium phosphate in soft tissues, which occurs in grazing cattle in Argentina and is of considerable economic importance. The ingestion of leaves of Solanum malacoxylon has been identified as the cause of the disease. Hypercalcemia and/or hyperphosphatemia and mineralization of the cardiovascular and pulmonary systems are usually seen in bovines or experimental animals exposed to this plant. The symptoms of the disease resemble those of vitamin D intoxication. In agreement with these observations, a glycoside derivative of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the hormonally active form of vitamin D in animals, has been identified as the toxic principle of S. malacoxylon. Glycoside conjugates of its precursors, 25-hydroxyvitamin D3 and vitamin D3, may also be present. Recent studies indicate that the plant factor is modified in the rumen of bovines through cleavage of the glycosidic linkage and further conversion of the released 1,25(OH)2D3 to a more polar metabolite, possibly 1,24,25-trihydroxyvitamin D3. Excess free 1,25(OH)2D3 may alter extracellular and intracellular Ca homeostasis in intoxicated animals through a receptor-mediated mechanism and activation of membrane Ca channels. In addition, 1,24,25(OH)3D3 may potentiate the effects of 1,25(OH)2D3 on intestinal Ca transport.
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PMID:Solanum malacoxylon: a toxic plant which affects animal calcium metabolism. 307 67

Interstitial pulmonary calcinosis was discovered after finding hypercalcaemia in a man of 56 who had been treated for several months with Hydrochlorthiazide. This was a secondary hyperparathyroidism due to the formation of parathyroid adenomatous cysts. This illness had been quiescent until then and was probably revealed as a result of the hydrochlorthiazide therapy.
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PMID:[Pulmonary calcinosis]. 344 75

A syndrome of pulmonary alveolar septal calcinosis, pneumothorax, and pneumomediastinum, leading to rapidly progressive acute respiratory insufficiency and death was observed in 2 children with acute lymphoblastic leukemia (ALL). Primary clinical and radiological considerations in these patients were pulmonary edema and infection, and the diagnosis of pulmonary alveolar septal calcification was established only at autopsy. One patient, a 15-year-old girl, was found also to have parathyroid hyperplasia typical of familial hyperparathyroidism. The other, a 16-month-old girl, showed osteitis fibrosa of the bones and parathyroid hyperplasia of secondary type, suggesting that the pulmonary calcinosis resulted from hypercalcemia caused by a parathormone or prostaglandin-secreting tumor. The cause of pneumothorax and pneumomediastinum may have been rupture of calcified alveolar septa induced by high PEEP during ventilation of these patients. Other possible mechanisms contributing to hypercalcemia and pulmonary calcinosis in children with acute leukemia include bone resorption due to marrow infiltration, immobilization syndrome, renal failure, and administration of calcium, phosphate, or bicarbonate. This complication of acute leukemia in childhood is rare (2 patients in 430 autopsied over the period 1961-1982 at Childrens Hospital of Los Angeles). How often the process can be reversed if diagnosed before severe respiratory insufficiency is present is not known.
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PMID:Pulmonary alveolar septal calcinosis causing progressive respiratory failure in acute lymphoblastic leukemia in childhood. 347 56

Pulmonary calcinosis is a recognized complication of renal failure. The resulting pulmonary compromise may be severe or even fatal. The potential contribution of hypercalcemia, hyperphosphatemia, and increased calcium-phosphorus product to the development of pulmonary calcinosis has been controversial. We describe four patients (ages 2 1/4 to 18 years) who had severe pulmonary calcinosis and respiratory failure within three to five days after renal transplantation. Initial clinical and roentgenographic findings suggested noncardiogenic pulmonary edema. Marked pulmonary hypertension was present in the two patients in whom pulmonary artery pressure data were available. Other clinical features in common included poor allograft function with persistent uremia requiring dialysis and evidence of moderate to severe secondary hyperparathyroidism. In three of the patients, the calcium-phosphorus product increased markedly after transplantation, to peak values of 122 to 147. This increase occurred at the same time as the onset of respiratory failure. Peak serum calcium levels were 10.0 to 11.0 mg/dL and peak serum phosphorus levels were 9.2 to 13.5 mg/dL. All patients died of respiratory failure five to 58 days after transplantation. The posttransplantation period may be a time of increased risk of potentially fatal pulmonary calcinosis in pediatric renal transplant recipients. The diagnosis should be considered in any patient with respiratory failure of unknown cause following renal transplantation.
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PMID:Pulmonary calcinosis after renal transplantation in pediatric patients. 352 Dec 66

Two patients with extensive tumoral calcinosis were treated with aluminium hydroxide. Initial metabolic studies showed positive calcium and phosphorus balances which became negative with aluminium hydroxide treatment. One subject, who had renal impairment, developed transient hypercalcaemia, parathyroid suppression, low levels of 1,25-dihydroxyvitamin D and calcium malabsorption during treatment with aluminium hydroxide. The second patient developed calcium malabsorption due to vitamin D deficiency. When she was replete with vitamin D there were supranormal levels of 1,25-(OH)2D in the serum and enhanced calcium absorption during treatment with aluminium hydroxide. Both subjects developed hypercalciuria and there was dissolution of many of the calcific tumours. The patient with renal impairment accumulated aluminium in the bone.
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PMID:Tumoral calcinosis: clinical and metabolic response to phosphorus deprivation. 365 64

Calcinosis, the process whereby calcium salts are deposited in soft tissues, may be idiopathic, metastatic or dystrophic. Metastatic calcinosis develops in a variety of systemic diseases characterized by either hypercalcemia, hyperphosphatemia, or both. Dystrophic calcinosis refers to calcification of previously damaged or necrotic tissue. It may be found accompanying inflammatory or degenerative conditions and is frequently associated with connective tissue diseases. When pathologic calcification is widespread, an attempt must be made to determine the underlying cause. A case is presented in which there was multifocal calcium deposition in soft tissues, including an intra-oral site. The patient also exhibited severe arthritis, sicca syndrome, focal alopecia and vitiligo. In view of this clinical spectrum, one of the "collagen diseases" (dermatomyositis, lupus erythematosus, rheumatoid arthritis, and scleroderma) was suspected as a predisposing factor for disseminated calcinosis. When diagnostic workup failed to reveal a specific connective tissue disease, it was concluded that "undifferentiated connective tissue disease" was responsible for dystrophic calcinosis.
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PMID:Oral lesion in a patient with calcinosis and arthritis: case report and differential diagnosis. 391 55

We describe a patient with rheumatoid arthritis and widespread joint and periarticular calcinosis related to self-medication with vitamin D, which was aggravated by oral phosphate therapy prescribed for her hypercalcaemia. Hydroxyapatite was shown in the synovial fluid from affected joints. The role played by tissue injury in the pathogenesis of soft tissue calcification is discussed.
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PMID:Calcinosis of joints and periarticular tissues associated with vitamin D intoxication. 402 10

Nonspecific calcinosis engendered by vitamin D3 is associated with extraosseous calcium deposits, in connection with which proteoglycans (PG) can be observed. After administration of vitamin D3 tissue samples from cardiac muscle and aorta of rats were taken and traced ultrahistochemically by means of the acriflavin-phosphotungstic acid contrast-method. The calcification began first with an increase in PG in the cell membranes of the sarcolemma, in the ground substance, and in the capillaries of the interstice. Subsequently circularly formed concentric layers of calcium encrustations appear in the above-mentioned locations. Large amounts of PG were also observed prior to the formation of crystalline fascicular calcium deposits in the ground substance and in the elastic fibers of the media of the aorta. This process began at the outer edges of the media and continued towards their interior, resulting in a loosening of the bond between the elastic fibers and the sarcoplasmic continuations of the smooth muscle cells. The extraosseous calcification resulting after the administration of vitamin D3 can therefore be considered not only as a result of hypercalcemia, but also as a result of stimulation of the production of ground substance through vitamin D3. This form of calcification represents a characteristic pathophysiological process which is differentiated from the dystrophic form in that it begins without previous cell damage.
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PMID:[Effect of vitamin D3 on the formation of proteoglycans and tissue calcification]. 630 25

Experimental chronic renal failure (CRF) in rats gave rise to azotemia, hyperphosphatemia, reduction in the proportion of the diaphyses, decrease in them of calcium, phosphorus and hydroxyproline, and to the lowering of the calcium content in the epiphyses. Administration to the animals of 0.025 microgram of 1,25-dioxycholecalciferol (1,25(OH)2D3) a day did not make the indicators under consideration return to normal. At the same time 1,25(OH)2D3 enhanced the degree of hyperphosphatemia and demineralization of the epiphyses, provoked moderate hypercalcemia and dramatically enhanced calcinosis in the aorta and in the remainder of the kidney. Administration of 24,25-dioxycholecalciferol (24,25(OH)2D3) in a dose of 0.25 microgram made the majority of the indicators return to normal, increasing the proportion of the diaphyses and the content in them of calcium and phosphorus, reducing the blood phosphorus content and the degree of azotemia. Furthermore, 24,25(OH)2D3 raised the collagen content in the diaphyses and epiphyses. A higher dose of 24,25(OH)2D3 (1.25 microgram) did not appear more effective. In none the doses applied, 24,25(OH)2D3 produced hypercalcemia or calcinosis. Combination of 1,25(OH)2D3 in a dose of 0,025 microgram and 24,25(OH)2D3 in a dose of 1,25 microgram slightly reduced the hypercalcemic, hyperphosphatemic and calcinosis-inducing effects of 1,25(OH)2D3, completely prevented osteoporotic alterations in the diaphyses, but enhanced the demineralization in the epiphyses, which may point to the advisability of reducing the doses of these metabolites on combined use. The data obtained indicate that 24,25(OH)2D3 is a more effective and safer agent for correcting the disturbances of the phosphorus-calcium metabolism and osseous lesions in CRF than 1,25(OH)2D3.
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PMID:[Effect of 24,25-dioxycholecalciferol on calcium-phosphorus metabolism and bone tissue in rats with experimental renal failure]. 633 22


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