Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020438 (hypercalciuria)
 2,502 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In normal individuals, 1,25-dihydroxyvitamin D (1,25-D) levels regulate calcium (Ca) absorption according to Ca intake; its synthesis is stimulated by low Ca intake, probably via increased parathyroid hormone (PTH) secretion, to increase Ca absorption, and suppressed during high intake to reduce Ca absorption. The body also adapts Ca absorption in response to renal Ca excretion, and phosphate absorption in response to phosphate intake. These adaptations may fail or be impaired in certain diseases. In disorders of overadaptation, the intestinal tract absorbs excessive amounts of Ca due to overproduction of 1,25-D, as in absorptive hypercalciuria, sarcoidosis, primary hyperparathyroidism, and tumoral calcinosis. Intestinal hyperabsorption and hypercalciuria may occur on both low- and high-Ca diets. Primary hyperparathyroidism and hypoparathyroidism are bihormonal, related to over- and underproduction, respectively, of both 1,25-D and PTH. Underadaptation disorders are typically related to low 1,25-D synthesis or resistance to this metabolite; examples include postmenopausal osteoporosis, chronic renal failure, and osteomalacia. Many of these adaptational disorders can be relieved or improved by manipulating Ca, phosphate, sodium, or protein intake or by administering exogenous 1,25-D. Overabsorption of Ca and other substances, such as oxalate, may be responsible for Ca nephrolithiasis. Hypocitraturia (which may be a complication of certain diseases or the result of unbalanced diet or excessive exercise), diets high in readily metabolizable sugars and purine-rich proteins (meat, poultry, and fish), and low fluid intake can all contribute to stone formation. Various regimens may reduce the risk of Ca nephrolithiasis.
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PMID:Calcium metabolism. 268 27

Kidney histology of five infants who died during or immediately after treatment with adrenocorticotrophic hormone (ACTH) showed severe tubular and interstitial calcinosis. We therefore studied serum concentrations of calcium, inorganic phosphate, and parathormone, serum activities of alkaline phosphatase, and urinary excretion of calcium, inorganic phosphate, and cyclic adenosine monophosphate (cAMP) in 16 other children with infantile spasms before, during, and after 6 weeks of treatment with ACTH. During the treatment the following observations were made: hypocalcaemia developed in three infants; the mean daily urinary excretion of calcium in the group increased threefold and seven infants had hypercalciuria; the excretion of phosphate increased but its tubular reabsorption remained stable; and in most infants serum parathormone and urinary cAMP excretion increased, and in four infants they increased to supranormal concentrations. These biochemical changes were reversible in most infants. Radiographs suggested loss of bone mass by 3-4 weeks of treatment, with rapid recovery after treatment. We conclude that infants treated with ACTH for infantile spasms are at risk of suffering disturbance in calcium and phosphate homeostasis, which leads to nephrocalcinosis.
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PMID:Disturbed calcium and phosphate homeostasis during treatment with ACTH of infantile spasms. 301 35

Pathologic calcium phosphate deposition occurs mainly in tissues exposed to highly supersaturated body fluids such as urine and saliva. In vitro models employed to study pathologic calcification include aqueous solutions and hydrogels. Results from studies on de novo formation of various biologic calcium phosphates in aqueous solutions resembling various body fluids have been rewarding. Among others, the de novo results have shown that the formation conditions for each calcium phosphate crystal phase are quite different and are pH dependent, and yet all phases including brushite can form in neutral solutions. This is an important finding because when coupled to the facts that all calcium phosphates including brushite are more soluble in acidic solutions than in neutral ones and that, except in extreme cases of hypercalciuria and/or hyperphosphaturia, body fluid Ca and Pi are not very high, it suggests that in most cases pathologic calcification occurs in alkaline or near neutral milieus. HAP is ubiquitous because it is the most insoluble calcium phosphate crystal phase in alkaline or slightly acidic fluids. In fluids close to neutrality, whitlockite is the next favored, provided that the fluid Mg:Ca ration is neither too low nor too high. Although OCP is only slightly more soluble than whitlockite in near neutral milieus, it is favored only by low fluid Ca:Pi and Mg:Ca ratios and transforms easily to HAP. Except in very acidic milieus, brushite is the most soluble biologic calcium phosphate. Its formation is favored by acidic body fluids with high Ca x Pi or by neutral or slightly alkaline ones with very low Ca:Pi ratio or high Mg:Ca ratio.
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PMID:Pathologic calcium phosphate deposition in model systems. 305 Nov 53

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

A patient with pseudoxanthoma elasticum was documented to be hyperphosphatemic and mildly hypercalcemic for six years. Complications included metastatic calcification, absorptive hypercalciuria, and renal insufficiency. The 1,25-dihydroxyvitamin D value was elevated, despite normal serum parathyroid hormone values, high serum phosphate levels, and renal insufficiency. Either increased dietary calcium or prednisone seemed to suppress the 1,25-dihydroxyvitamin D value. Nephrolithiasis or abnormalities suggestive of pseudoxanthoma elasticum occurred in the patient's father, daughter, and several siblings, suggesting a distinct familial syndrome in which connective tissue changes are accompanied by abnormalities of phosphorus and vitamin D metabolism that may resemble those in the syndrome of familial tumoral calcinosis. Nine similar cases were described before 1970.
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PMID:Heritable syndrome of pseudoxanthoma elasticum with abnormal phosphorus and vitamin D metabolism. 333 71

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

Prolonged treatment of premature infants with the potent diuretic furosemide has resulted in hypercalciuria, sometimes with renal calcinosis and other complications. Furosemide was administered to weanling rats to explore its effect on magnesium and calcium metabolism. The animals were fed purified diets providing 40 mg magnesium/100 g diet or 10 mg magnesium/100 g. Half of each dietary group (40-F or 10-F) received 18 doses of furosemide, 20 mg/kg body weight, intraperitoneally between days 7 and 35, and half received normal saline intraperitoneally (40-O or 10-O). Furosemide had little effect on the magnesium-sufficient animals (40-F), but comparison of 10-O and 10-F data showed that it aggravated the magnesium-deficiency syndrome. Comparison of data from 40-F and 10-F animals showed the protective effect of magnesium in preserving calcium homeostasis in furosemide-treated animals: the elevation of calcium values in 10-F rats was greater in plasma (p less than 0.0005), heart (p less than 0.0025), and kidney (p less than 0.0005). Stated another way, furosemide was associated with severely disordered calcium metabolism only in animals fed suboptimal magnesium. Studies exploring the role of magnesium in furosemide-treated infants can be recommended.
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PMID:Protection by magnesium of renal calcinosis in furosemide-treated weanling rats with moderate magnesium deficiency. 404 3

A 50-year-old Latin American man with tumoral calcinosis presented with hyperphosphatemia (6.62 +/- 1.04 SD mg/dl), elevated renal threshold phosphorus concentration (TmP) (7.3 mg/GFR), and 1,25-dihydroxyvitamin D [1,25-(OH)2D] (69 pg/ml) hypercalciuria (239 mg/day), and a high fractional intestinal calcium (Ca) absorption (0.74). Sodium cellulose phosphate therapy (20 g/day) lowered urinary Ca, and partially reduced serum phosphorus (P) and TmP to 5.91 +/- 0.63 mg/dl and 6.2 mg/GFR, respectively. Serum 1,25-(OH)2D remained elevated at 58-64 pg/ml. Amphojel therapy (4 oz/day) decreased urinary P to 23 +/- 21 mg/day and lowered serum P to 5.75 +/- 0.36 mg/dl (P < 0.05). TmP increased to a value of 8.0 mg/GFR while serum 1,25-(OH)2D continued to remain elevated at 53 pg/ml. This case illustrates the probable operation of dual abnormalities in tumoral calcinosis represented by augmented renal conservation of P and an elevation in the circulating concentration of 1,25-(OH)2D.
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PMID:Tumoral calcinosis: evidence for concurrent defects in renal tubular phosphorus transport and in 1 alpha,25-dihydroxycholecalciferol synthesis. 677 76

Idiopathic low-molecular-weight (LMW) proteinuria is a newly described renal disease in Japan and Italy. We report on 7 patients who manifested bilateral or unilateral nephrocalcinosis, as demonstrated by abdominal computed tomography scans. Renal histology revealed calcinosis of renal tubules in 2 patients. Computed tomography is a reliable method for the detection of nephrocalcinosis in this disorder. Hypercalciuria was also seen in 6 patients. A calcium-loading test performed in 2 patients suggested that hypercalciuria was of renal origin. Although the true pathogenesis is still not known, hypercalciuria and nephrocalcinosis appear to be a common complication in patients with idiopathic LMW proteinuria. These complications and clinical features suggest that idiopathic LMW proteinuria in Japan is likely to be identical to Dent's disease in the United Kingdom.
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PMID:Hypercalciuria and nephrocalcinosis in patients with idiopathic low-molecular-weight proteinuria in Japan: is the disease identical to Dent's disease in United Kingdom? 775 56

Increased renal medullary echogenicity by renal ultrasound associated with hypercalciuria and nephrocalcinosis is often present in childhood. 17 children, 9 boys and 8 girls, aged from 8 months to 10 years were classified into three groups based on ultrasound findings according to Patriquin and Robitaille: type A faint hyperechogenic rim around the sides and tip of the medullary pyramid; type B more intense echogenic rim of the pyramids; type C intense echoes throughout the pyramid. Clinic-echographic correlations showed a pattern C in 4 children with distal renal tubular acidosis and in an infant treated with furosemide; pattern B in 3 patients having different types of tubulopathy associated with hypercalciuria; pattern A in 6 children with congenital tubulopathy and in 3 children treated with vitamin D. Abdominal X-rays detected medullary calcinosis in 2 (11.7%) of total 17 patients. Ultrasonography appears to be an important tool in early diagnosis of renal medullary nephrocalcinosis.
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PMID:[Hyperechogenicity of the renal medulla in children: clinico-echographic correlations]. 916 41


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