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)

Nineteen children with clinical diagnoses of renal tubular acidosis were followed for periods ranging from 3 months to 20 years. Twelve patients had Type 1 renal tubular acidosis, five had Type 2, and two had Type 4. No sex predilection was found for any one of the types. Most patients had been diagnosed before 18 months of age, with failure to thrive the most common presentation. Tachypnea, polydipsia, polyuria, and vomiting were frequent symptoms. Some of these children had associated renal hypoplasia, vesicoureteral reflux, unilateral renal agenesis, glomerulocystic disease, adult polycystic kidney disease, and cyanotic congenital heart disease. Urinary anion gap may be useful for differential diagnosis of altered distal urinary acidification from other hyperchloremic metabolic acidosis. Furosemide test may need further investigation. Inability to raise urine to blood pCO2 gradient is helpful for diagnosis of Type 1 renal tubular acidosis. Hypokalemia, hypocalcemia, hypophosphatemia, decreased tubular reabsorption of phosphate, and hypercalciuria occurred in some patients. Complications included rickets in two, nephrocalcinosis in one, and episodic hematuria in one. There was relative bicarbonate wasting in children with Type 1 renal tubular acidosis, with a mean therapeutic bicarbonate requirement of 4.4 +/- 2.6 meq/kg/day. The mean bicarbonate dose for patients with Type 2 renal tubular acidosis was 8.3 +/- 2.6 meq/kg/day. Most children had good response to treatment with complete catch-up linear growth in 13, improved growth in 4, and continuing poor growth in 2. Two patients died during follow-up. Two other patients maintained normal growth without medication.
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PMID:Renal tubular acidosis in childhood. 226 80

Nephrocalcinosis was observed in 3 children of one family with distal renal tubular acidosis (dRTA). At presentation, all 3 patients had failure to thrive, rickets, hyperchloremic metabolic acidosis, hypokalemia, hypophosphatemia and hypercalciuria. At a later age, sensorineural hearing impairment was detected. Nephrocalcinosis was diagnosed in the index case at the age of 5 years, when a plain abdominal roentgenogram was first made; in the younger brother and sister, nephrocalcinosis was detected earlier at the age of 4 months and 5 weeks, respectively. All 3 patients required large doses of alkali (7.5-9.5 mEq/kg body weight/day) during infancy and early childhood to correct the acidosis and to prevent progression of the nephrocalcinosis. Contrary to the current notion that in children with dRTA, nephrocalcinosis is observed only after the age of 3 years, it appears that in some instances nephrocalcinosis may develop in early infancy. The occurrence of nephrocalcinosis at a very young age may be a manifestation of a severe genetically transmitted variant of dRTA and emphasizes the need for early diagnosis and optimal treatment of these patients from the first days of life.
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PMID:Familial distal renal tubular acidosis with neurosensory deafness: early nephrocalcinosis. 259 37

Some children with Bartter syndrome have hypercalciuria. To determine the mechanism for this phenomenon, we studied tubular function and calcium metabolism in six such children. All patients had hypokalemic alkalosis, normotension, hyperreninemia, growth retardation, low fractional distal chloride reabsorption (4/5), and elevated urinary prostaglandin E2 excretion (5/6). In addition, all had hypercalciuria (urinary calcium 6.5 to 25.0 mg/kg/day), with evidence of nephrocalcinosis in five. None, however, had evidence of rickets or hyperparathyroidism. There was a marked elevation in the serum concentration of 1,25-dihydroxyvitamin D in all, and four patients had a response to oral calcium loading suggestive of absorptive hypercalciuria. Five children have had long-term therapy with indomethacin. They have had improvement in hypokalemia and reduced urinary prostaglandin E2 excretion as well as reductions in the serum concentration of 1,25-dihydroxyvitamin D and in urinary calcium excretion. These data suggest that hypercalciuria in some children with Bartter syndrome is associated with an excess of 1,25-dihydroxyvitamin D. The improvement in hypercalciuria with prostaglandin synthesis inhibition may result in part from correction of this vitamin D abnormality.
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PMID:Hypercalciuria with Bartter syndrome: evidence for an abnormality of vitamin D metabolism. 267 27

A 14-year-old Turkish boy had severe rickets that had been clinically evident since he was 2 years of age. When he was 5 years of age, he had normal serum calcium and phosphorus levels and increased alkaline phosphatase activity. Treatment with modest dosages of vitamin D (5000 U/d for 3 weeks) resulted in hypercalcemia. At 10 years of age, high-dose vitamin D (40,000 U/d) plus phosphorus (1.1 g/d) therapy for 20 days resulted in symptomatic nephrolithiasis. When, 14 years of age, he had normocalcemia, hypophosphatemia, increased alkaline phosphatase activity, and normal circulating parathyroid hormone concentration. Levels of 25-hydroxyvitamin D were normal but those of 1,25-dihydroxyvitamin D were markedly increased. Rickets and osteopenia were evident on radiographs, and osteomalacia was present on trabecular bone obtained at biopsy. Balance study results showed increased intestinal absorption of calcium and phosphorus, hypercalciuria, and increased urinary phosphorus excretion. This patient manifests an unusual form of hypophosphatemic rickets in which hypercalciuria is a cardinal feature. In contrast with most varieties of hypophosphatemia, this disorder is characterized by appropriately increased production of 1,25-dihydroxyvitamin D in response to hypophosphatemia. It is recommended that urinary calcium excretion be assessed in all patients with hypophosphatemic rickets so that appropriate therapy will be instituted.
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PMID:Hypercalciuric hypophosphatemic rickets, mineral balance, bone histomorphometry, and therapeutic implications of hypercalciuria. 278 97

Renal ultrasonography was performed on 23 patients with X-linked hypophosphatemic rickets (XLH) and 11 patients with autosomal recessive vitamin D-dependent rickets (ARVDD). A pattern of increased echogenicity of the renal pyramids (ERP) was identified in 11/23 patients with XLH and 3/11 patients with ARVDD; this ultrasonographic finding has previously been associated with medullary nephrocalcinosis. Patients with XLH and ERP had significantly higher mean serum calcium and phosphate concentrations, more frequent episodes of hypercalcemia, and higher doses of oral vitamin D and phosphate during the first 3 years of therapy. Episodes of hypercalcemia were more frequent when patients received higher doses of vitamin D2 (greater than 4000 IU/kg/day) or 1,25-dihydroxycholecalciferol (greater than 40 ng/kg/day). Episodes of hypercalciuria were significantly increased at doses of greater than 20 ng/kg/day 1,25-dihydroxycholecalciferol. In patients with ARVDD, ERP was also correlated with vitamin D dose and frequency of hypercalcemia episodes. ERP was not associated with an elevation of serum creatinine or loss of urinary concentrating ability in either patient group.
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PMID:Nephrocalcinosis and its relationship to treatment of hereditary rickets. 282 87

A familial observation of hypophosphatemic rickets with unusual inheritance and evolution, different from that of X linked hypophosphatemia, is reported. The mode of inheritance was autosomal dominant, a father and his son being affected. Severe early signs of rickets and delayed growth were present in both cases. Plasma 1,25 dihydroxyvitamin D and PTH levels were normal. There was no hypercalciuria. Complete cure of rickets and catch-up growth were obtained with the only treatment of vitamin D (40,000 U/day) in the father and of 1 alpha hydroxyvitamin D (1 microgram/day) in the son. This observation is quite similar to the 'autosomal hypophosphatemic bone disease' described by Scriver et al. It illustrates the heterogeneity of familial hypophosphatemia which presently includes 4 different physiopathological entities.
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PMID:[Scriver type autosomal hypophosphatemic rachitis: a family case]. 283 21

We studied a new hereditary syndrome of hypophosphatemic rickets and hypercalciuria in six affected members of one kindred. In all patients, the manifestations of disease began in early childhood. The characteristic features are rickets, short stature, increased renal phosphate clearance (the ratio between the maximal tubular reabsorption rate for phosphorus and the glomerular filtration rate [TmP/GFR] is 2 to 4 S.D. below the age-related mean), hypercalciuria (8.6 mg of urinary calcium per kilogram of body weight per 24 hours vs. the upper normal value of 4.0), normal serum calcium levels, increased gastrointestinal absorption of calcium and phosphorus, an elevated serum concentration of 1,25-dihydroxyvitamin D (390 +/- 99 pg per milliliter vs. the upper normal value of 110), and suppressed parathyroid function (an immunoreactive parathyroid hormone level of 0.33 +/- 0.1 ng per milliliter and a cyclic AMP level of 1.39 +/- 0.12 nmol per deciliter of glomerular filtrate vs. the lower normal values of 0.3 and 1.5, respectively). Long-term phosphate supplementation as the sole therapy resulted in reversal of all clinical and biochemical abnormalities except the decreased TmP/GFR. We propose that the pivotal defect in this syndrome is a renal phosphate leak resulting in hypophosphatemia with an appropriate elevation of 1,25-dihydroxyvitamin D levels, which causes increased calcium absorption, parathyroid suppression, and hypercalciuria. This syndrome may represent one end of a spectrum of hereditary absorptive hypercalciuria. Our observations support the importance of phosphate as a mediator in controlling 1,25-dihydroxyvitamin D production in human beings.
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PMID:Hereditary hypophosphatemic rickets with hypercalciuria. 298 3

Extensive metabolic studies were performed in a 14-year-old boy suffering from the rare clinical entity known as childhood idiopathic hypercalciuria associated with dwarfism, renal tubular abnormalities and bone lesions. The salient features were: hyperphosphaturia with hypophosphatemia, hypercalciuria with normocalcemia, elevated serum 1,25-dihydroxycholecalciferol[1,25(OH)2D3] levels, marked intestinal hyperabsorption of calcium and phosphorus, with low serum parathyroid hormone (PTH) and urinary adenosine 3':5'-cyclic monophosphate (c-AMP). Bone biopsy confirmed the clinical and radiological diagnosis of rickets. It appears that the following pathophysiological sequence is operating: primary renal phosphate leak with hypophosphatemia, increased 1,25(OH)2D3 synthesis, enhanced intestinal calcium absorption which in turn inhibits release of PTH and c-AMP. Hypercalciuria is seen to be secondary to both avid intestinal calcium absorption and depressed PTH activity, and rickets the result of phosphate depletion. Treatment with oral phosphorus only resulted in an acceleration of growth rate, cure of rickets, and return of urinary calcium excretion to normal values.
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PMID:Hypercalciuric rickets: metabolic studies and pathophysiological considerations. 298 52

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 14-year-old boy presented with the clinical and radiological features of rickets. Serum inorganic phosphate levels were constantly low, whereas serum calcium and parathyroid hormone levels were within the normal range. Laboratory investigation did not show any evidence for vitamin-D deficiency, chronic renal insufficiency, Fanconi syndrome, tubular acidosis, hepatic disease or intestinal malabsorption. A family study comprising 34 members over four generations revealed 10 other individuals to be affected and the mode of inheritance to be autosomal dominant. In addition to hypophosphataemia and normocalcaemia, the disease is characterized by elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria. This hereditary syndrome of renal hypophosphataemia differs from the common familial X-linked hypophosphataemia and the recently described autosomal recessive hypophosphataemic rickets with hypercalciuria by its dominant mode of inheritance; it differs from hypophosphataemic non-rachitic bone disease by the elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria.
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PMID:Autosomal dominant hypophosphataemia with elevated serum 1,25 dihydroxyvitamin D and hypercalciuria. 315 20


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