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)

Six children with idiopathic hypercalciuria and their families were examined with an oral calcium loading test. Family members were divided into two clinical categories: group 1 consisted of the six index children and their parents and siblings with urolithiasis or unexplained hematuria; group 2 comprised the remaining parents and siblings without signs or symptoms associated with hypercalciuria. The results revealed that fasting urinary excretion of calcium was similar in both groups, but group 1 displayed a greater calciuric response to an oral calcium load. Serum concentrations of calcitriol (1,25-dihydroxyvitamin D3) and calcium were higher in group 1 than in group 2, while parathyroid activity was lower in group 1 patients. Urinary excretion of sodium, phosphorus, and magnesium, urine pH, serum levels of calcifediol (25-hydroxyvitamin D3) and phosphorus, and the renal tubular threshold for phosphate were not significantly different in the two groups. These findings suggest that idiopathic hypercalciuria may arise from a disturbance in the regulation of vitamin D metabolism that mediates enhanced intestinal absorption of calcium.
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PMID:Families of children with idiopathic hypercalciuria. Evidence for the hormonal basis of familial hypercalciuria. 383 4

Although conventional therapy (pharmacologic doses of vitamin D and phosphorus supplementation) is usually successful in healing the rachitic bone lesion in patients with X-linked hypophosphatemic rickets, it does not heal the coexistent osteomalacia. Because serum 1,25-dihydroxyvitamin D levels are inappropriately low in these patients and high calcitriol concentrations may be required to heal the osteomalacia, we chose to treat five affected subjects with high doses of calcitriol (68.2 +/- 10.0 ng/kg total body weight/d) and supplemental phosphorus (1-2 g/d) performing metabolic studies and bone biopsies before and after 5-8 mo of this therapy in each individual. Of these five patients, three (aged 13, 13, and 19 yr) were receiving conventional treatment at the inception of the study and therefore showed base-line serum phosphorus concentrations within the normal range. The remaining two untreated patients (aged 2 and 37 yr) displayed characteristic hypophosphatemia before calcitriol therapy. All five patients demonstrated serum calcitriol levels in the low normal range (22.5 +/- 3.2 pg/ml), impaired renal phosphorus conservation (tubular maximum for the reabsorption of phosphate per deciliter of glomerular filtrate, 2.13 +/- 0.20 mg/dl), and osteomalacia on bone biopsy (relative osteoid volume, 14.4 +/- 1.7%; mean osteoid seam width, 27.7 +/- 3.7 micron; mineral apposition rate, 0.46 +/- 0.12 micron/d). On high doses of calcitriol, serum 1,25-dihydroxyvitamin D levels rose into the supraphysiologic range (74.1 +/- 3.8 pg/ml) with an associated increment in the serum phosphorus concentration (2.82 +/- 0.19 to 3.78 +/- 0.32 mg/dl) and improvement of the renal tubular maximum for phosphate reabsorption (3.17 +/- 0.22 mg/dl). The serum calcium rose in each patient while the immunoactive parathyroid hormone concentration measured by three different assays remained within the normal range. Most importantly, repeat bone biopsies showed that high doses of calcitriol and phosphorus supplements had reversed the mineralization defect in all patients (mineral apposition rate, 0.88 +/- 0.04 micron/d) and consequently reduced parameters of bone osteoid content to normal (relative osteoid volume, 4.1 +/- 0.7%; mean osteoid seam width, 11.0 +/- 1.0 micron). Complications (hypercalcemia and hypercalciuria) ensued in four of these five patients within 1-17 mo of documented bone healing, necessitating reduction of calcitriol doses to a mean of 1.6 +/- 0.2 micrograms/d (28 +/- 4 ng/kg ideal body weight per day). At follow-up bone biopsy, these four subjects continued to manifest normal bone mineralization dynamics (mineral apposition rate, 0.88 +/-0.10 micrometer/d) on reduced doses of 1.25-dihydroxyvitamin D with phosphorus supplements (2 g/d) for a mean of 21.3 +/- 1.3 mo after bone healing was first documented. Static histomorphometric parameters also remained normal (relative osteoid volume, 1.5 +/- 0.4%; mean osteoid seam width, 13.5 +/- 0.8 micrometer). These data indicate that administration of supraphysiologic amounts of calcitriol, in conjunction with oral phosphorus, results in complete healing of vitamin D resistant osteomalacia in patients with X-linked hypophosphatemic rickets. Although complications predictably require calcitriol dose reductions once healing is achieved, continued bone healing can be maintained for up to 1 yr with lower doses of 1,25-dihydroxyvitamin D and continued phosphorus supplementation.
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PMID:Healing of bone disease in X-linked hypophosphatemic rickets/osteomalacia. Induction and maintenance with phosphorus and calcitriol. 383 45

Recent data suggest a causal role of deranged 1,25(OH)2D metabolism in the syndrome of idiopathic hypercalciuria. To test this hypothesis, we evaluated if vitamin D availability and/or increased serum 1,25(OH)2D were critical for the expression of hypercalciuria in laboratory rats. Ca balance, serum 25OHD3, and 1,25(OH)2D3 were studied in D-deprived (-D) and D-repleted (+D) male progeny (p) born to normocalciuric (NC) and spontaneously hypercalciuric (SH) rats. 7 of the 14 pSH and 2 of 21 pNC had SH, which was defined as urinary Ca greater than two standard deviations above the mean of values for control animals on days 5 and 6 of a low Ca +D diet (1.19 vs. 0.58 mg/d, P less than 0.001). Fasting serum Ca and 25OHD3 were similar to control. Serum 1,25(OH)2D3 was elevated in these nine SH rats (232 vs. 145 pg/ml, P less than 0.005). However, during vitamin D deprivation, their Ca excretion was also increased (1.53 vs. 0.45 mg/d, P less than 0.001), despite comparably reduced serum 1,25(OH)2D3 (102 vs. 106 pg/ml) and undetectable serum 25OHD3. Net intestinal Ca absorption on a low Ca diet was comparable during D repletion (-0.75 vs. -0.82 mg/d) or D deprivation (-0.80 vs. -2.15 mg/d), excluding primary hyperabsorption as the mediator of the hypercalciuria. Mild hypophosphatemia was present in SH on +D (5.8 vs. 6.9 mg/dl, P less than 0.005) and -D diets (6.2 vs. 7.9 mg/dl, P less than 0.005), and was associated with higher rates of cyclic adenosine monophosphate excretion (32.8 vs. 26.9 and 48.5 vs. 41.0 nmol/mg of creatinine, respectively). Spontaneous hypercalciuria is therefore dissociable from increased Ca absorption, serum levels of 25OHD3, or 1,25(OH)2D3. The data are most compatible with the hypothesis of a renal Ca leak which stimulates parathyroid hormone activity and increases serum 1,25(OH)2D3, if provided adequate 25OHD3 as substrate.
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PMID:Pathophysiology of spontaneous hypercalciuria in laboratory rats. Role of deranged vitamin D metabolism. 383

The effect of two doses of Phosphorus (P) supplementation to pooled breast milk (BM): 0.48 and 0.800 mmol/kg/24 h given during the second month of life was evaluated in 22 very low birthweight infants. The concentration of calcium and phosphorus in serum and urine, the serum concentration of immunoreactive parathyroid hormone (iPTH) and the plasma 1,25-dihydroxy-vitamin D concentration (1,25-OH-D) were compared to the values in 19 control infants. The mean +/- SD concentrations in control infants and adults are 63 +/- 18 microliters Eq/ml for serum iPTH and 85 +/- pmol/l for plasma 1,25-OH-D. With 0.48 P supplementation, urinary Ca (UCa) excretion (median and range) 0.238 mmol/kg/24 h (0.105-0.520) was lower than in the control group 0.288 (0.205-0.679) (p less than 0.05); the reduction of UCa was larger with 0.8 P supplementation: 0.047 (0.023-0.163) (p less than 0.01). P supplementation induced no change in serum Ca concentration but a slight and significant increase in serum iPTH was observed only with the 0.8 P supplementation: 55 microliters Eq/ml (less than 25-80) (p less than 0.05). With 0.8 P supplementation there was no significant change of plasma 1,25-OH-D concentration: 173 pmol/l (106-271) vs. 255 (132-293) in the control group. These data show that with 0.8 P supplementation, the hypercalciuria in BM-fed infant disappears without secondary hyperparathyroidism, but without any change in plasma 1,25-OH-D concentration.
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PMID:Effect of phosphate supplementation to breast fed very low birthweight infants on urinary calcium excretion, serum immunoreactive parathyroid hormone and plasma 1,25-dihydroxy-vitamin D concentration. 384 Mar 17

We have studied a hypercalcemic patient with sarcoidosis and advanced renal failure. Bone biopsy and urinary cAMP excretion indicated suppression of parathyroid function. 1,25(OH)2D levels were moderately elevated and dropped to low normal levels during prednisolone treatment. Discontinuation of prednisolone treatment caused deterioration of renal function and hypercalcemia, 1,25(OH)2D serum levels being within the normal range. Our data demonstrate the rapid speed at which prednisolone causes a drop in serum 1,25(OH)2D level. Since hypercalcemia was observed both during periods of hypercalciuria and normal serum 1,25(OH)2D levels, increased sensitivity to active vitamin D seems likely. There was no significant correlation between 25(OH)D, 24,25(OH)2D or 25,26(OH)2D. Furthermore there was no correlation between any of these three metabolites and either 1,25(OH)2D or serum calcium.
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PMID:Rapid effect of prednisolone on serum 1,25-dihydroxycholecalciferol levels in hypercalcemic sarcoidosis. 384 60

A 52-year-old man with an acromegalic appearance of prolonged duration suffered abdominal colic attacks and hematuria during the middle of the course of the disease. The patient was diagnosed as having urolithiasis caused by increased urinary calcium. The calcium metabolic disorder was not considered to be due to hyperparathyroidism because serum calcium and PTH levels were within the normal range and no abnormality was observed in a parathyroidal scintigraph. The serum 1,25-dihydroxyvitamin D (1,25-(OH)2D) levels (55.0 and 73.0 pg/ml) were higher than the normal range (27.2-53.8 pg/ml). A selective adenomectomy by the transsphenoidal route (Hardy's method) was performed, resulting in an improvement in the hypercalciuria and urolithiasis, and a decrease in the levels of serum 1,25-(OH)2D (23.0 and 23.0 pg/ml). These findings suggest that GH may promote the activation of vitamin D in the kidney in acromegaly, resulting in an acceleration of calcium absorption in the intestine through the action of activated vitamin D and the induction of increased urinary calcium excretion by the urinary excretion of excessive blood calcium.
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PMID:An acromegalic patient with recurrent urolithiasis. 384 20

Abnormalities of mineral metabolism remain a clinical problem after successful renal transplantation. These disturbances may be the result of derangements in divalent ion, parathyroid hormone (PTH) and/or vitamin D metabolism. We therefore measured serum Ca, phosphorus, PTH and 1,25-dihydroxyvitamin D [1,25(OH)2D] levels and fractional intestinal Ca absorption (alpha) in 6 patients before and after successful transplantation (early, less than or equal to 6 months). 3 were reexamined later (late, greater than or equal to 24 months after transplantation). The patients exhibited decreased serum levels of 1,25(OH)2D and alpha before the renal transplantation. In the early stages, renal transplantation reduced serum phosphorus from 5.55 +/- (SD)1.96 to 2.96 +/- 0.95 mg/dl (p less than 0.02); this was accompanied by a rise in serum 1,25(OH)2D from 8.7 +/- 1.5 to 26.3 +/- 8.4 pg/ml (p less than 0.005). The calcemic response to PTH infusion became normal, since the increment in serum Ca rose from 0.45 +/- 0.21 mg/dl before transplantation to 1.03 +/- 0.18 mg/dl early after transplantation. Although the mean value for alpha increase significantly from 0.263 +/- 0.048 to 0.402 +/- 0.175 (p less than 0.05), alpha was subnormal in 3 patients (alpha less than 0.37). Urinary Ca was high in 3 patients, and it exceeded absorbed Ca (from intestines) in 4 patients (indicative of negative Ca balance). Serum PTH fell significantly but remained above normal. It was hoped that late after transplantation, when patients were maintained on smaller doses of oral glucocorticoids, these abnormalities would be ameliorated. However, hypercalciuria was found in 2 of 3 patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Disturbances in mineral metabolism after successful renal transplantation. 389 64

Vitamin K promotes the formation of gamma-carboxylated glutamate (GLA) in several protein species. GLA residues have a high affinity for the Ca ion. In the present study, we tested the hypothesis that experimental vitamin K deficiency in rats could induce changes in Ca metabolism. Vitamin K depletion, which was associated with a reduction in urinary GLA excretion, induced within 7 days a significant increase in cumulative urinary Ca excretion that persisted throughout the 21 days of study. The hypercalciuria of vitamin K-deficient rats was corrected on vitamin K supplementation. No concomitant changes were observed in intestinal Ca absorption determined by a balance technic or of skeletal resorption and apposition rates determined by bone histomorphometry. Plasma Ca, but not total protein concentration, of vitamin k-depleted rats showed a transient decrease at day 15 that disappeared at day 21. plasma sodium, phosphate and 1,25(OH)2 vitamin D concentration, and urinary phosphate, sodium, and creatinine excretion remained unchanged. In conclusion, vitamin k deficiency in the rat induced hypercalciuria that could be of renal origin. Its possible relationship to vitamin K-dependent renal GLA protein remains to be clarified.
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PMID:Hypercalciuria during experimental vitamin K deficiency in the rat. 392 70

Combination of 1 alpha(OH) D3(vit D) and ethylene glycol induced renal or ureteral stones or both consisting of calcium oxalate in male Wistar rats. This study investigates the effect of EHDP on calcium oxalate stone using the rat model. EHDP reduced the frequency of renal stone and calcium content in the kidney, and reduced the size of the stones in the renal pelvis and ureter. EHDP biochemically ameliorated renal injury induced by vit D and ethylene glycol. EHDP suppressed urinary excretion of calcium even though serum calcium slightly increased. EHDP had a phosphaturic action. EHDP elevated urinary excretion of magnesium. However, the severity of hypermagnesuria decreased in the rat which was not given EHDP concomitantly. Although EHDP slightly elevated urinary excretion of oxalate in the control rat, it did not affect the high level of urinary oxalate in the vit D/ethylene glycol rat. EHDP did not produce any histological change in the kidney or femoral bone. These data indicate that EHDP can suppress renal stone formation in the vit D/ethylene glycol rat. It is speculated that firstly, EHDP may physicochemically inhibit stone formation in the process of nidus, aggregation and crystal growth of calcium oxalate, under the supersaturated condition of calcium oxalate in the urine, and secondly, EHDP may endocrinologically inhibit production of 1,25 (OH)2 vit D in the kidney or inhibit 1, 25 (OH)2 vit D-mediated intestinal calcium absorption. It is suggested that in order to prevent stone recurrence, EHDP may be clinically applied not only to calcium phosphate stones but also to calcium oxalate stones and hypercalciuria mediated by an active form of vitamin D.
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PMID:[Effect of etidronate disodium (EHDP) on calcium oxalate renal stones induced by synthetic 1 alpha(OH) vitamin D3 and ethylene glycol in rats]. 393 44

The frequency of renal tubular acidosis was evaluated in 28 adult patients with recurrent calcium nephrolithiasis (19 with 'renal' hypercalciuria, 9 with normocalciuria and no metabolic abnormality) and no evidence of obstruction or infection of the urinary tract. Eight patients with hypercalciuria (42%) had a defective renal reabsorption of bicarbonate, based on a fractional excretion of bicarbonate higher than 7% and a TmHCO3/GFR lower than 2.2 mEq/dl; 2 of them had an associated distal defect of acidification, as judged by a U-B pCO2 lower than 18 mm Hg in maximally alkaline urine. One patient with hypercalciuria had distal tubular acidosis, based on a urine pH higher than 5.3 during acidosis. Only 1 patient with normocalciuria had associated proximal and distal acidification defects. The remaining 8 patients displayed a normal renal acidifying capacity. The bicarbonate wastage was independent of serum PTH levels, vitamin D status and hypercalciuria and was associated with a defective tubular reabsorption of phosphate, increased random urinary pH and more active nephrolithiasis, with a prevalence of mixed calcium oxalate and phosphate stones. Our study shows a high incidence of defective tubular reabsorption of bicarbonate in patients with calcium nephrolithiasis and 'renal' hypercalciuria and suggests that the proximal acidification defect plays a pathogenetic role in promoting calcium nephrolithiasis.
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PMID:Renal acidification defects in patients with recurrent calcium nephrolithiasis. 406 1


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