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)

Prolonged immobilization may result in hypercalcemia, hypercalciuria, and osteoporosis. Although bone resorption is central to this syndrome, the mechanism of resorption is uncertain. In particular, the role of systemic calcium-regulating hormones remains unclear. In 14 immobilized subjects we measured fasting calcium excretion, 24-hour urinary calcium excretion during restricted calcium intake, the renal phosphorus threshold, plasma 1,25-dihydroxyvitamin D, nephrogenous cyclic AMP, and immunoreactive parathyroid hormone. Mean serum calcium levels were normal, but fasting and 24-hour calcium excretion were markedly elevated (0.28 mg per deciliter of glomerular filtrate and 314 mg per 24 hours, respectively). The mean levels of serum phosphorus (4.8 mg per deciliter) and the renal phosphorus threshold (4.3 mg per deciliter) were elevated. Mean plasma 1,25-dihydroxyvitamin D was strikingly reduced (9.9 pg per milliliter), as were nephrogenous cyclic (0.64 nmol per deciliter of glomerular filtrate) and immunoreactive parathyroid hormone in both assays. These findings indicate that the parathyroid--1,25-dihydroxyvitamin D axis is suppressed in patients with immobilization-induced hypercalciuria, as would be predicted by a model of resorptive hypercalciuria.
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PMID:Calcium homeostasis in immobilization: an example of resorptive hypercalciuria. 628 47

Recently it has been observed that Ca excretion in laboratory rats does not follow a Gaussian distribution, with approximately 10% of them excreting Ca at a rate of 2 SD above the group mean. This phenomenon has been described as spontaneous hypercalciuria (SH). Our studies were designed to define its mechanism. 48 Wistar rats were subjected to metabolic studies to identify SH, prospectively defined as Ca excretion 2 SD above the group mean during 7 d of dietary Ca deprivation (</=0.03% by analysis), in the absence of hypercalcemia, PO(4) depletion, or exaggerated natriuresis. Progenies from SH rats were found to have significantly higher urine Ca/creatinine (micrograms per milligram) (male = 38 vs. 23, P < 0.05; female = 79 vs. 60, P < 0.005) with 7/20 males and 9/26 females having values 2 SD above the means of normal. After a 12-h fast and during 10% volume expansion with saline, clearance and micropuncture studies were performed on three groups of acutely parathyroidectomized female rats; (a) normocalciuric (N) progenies from the normal, (b) normocalciuric (NC) progenies from SH, and (c) hypercalciuric (HC) progenies from SH rats. Among these groups, there was no significant difference in body weights, glomerular filtration rate, plasma ultrafiltrable Ca (4.5, 4.6 vs. 4.7 mg/100 g), PO(4), and the fractional excretion (FE) of Na or FE(PO4). FE Ca was significantly higher in HC rats (13.9%) than N (10.1%) and NC (10.7%). Segmental reabsorption of fluid and Na was comparable among the three groups. Fractional delivery (FD) of Ca was, however, significantly increased in the late proximal tubule of HC rats (62 vs. 49 and 46%, P < 0.05). The increased FDCa was no longer apparent in early or late distal tubule (6.9 vs. 6.9 and 7.6%, P = NS). Although FECa exceeded late distal FDCa in all three groups, the increment was significantly greater in HC rats (7.02%) than both N (3.4, P < 0.05) and NC rats (3.05, P < 0.02). The effects of chlorothiazide (27.5 mg/kg/d, i.p. x 7 d) were evaluated in the female offsprings of the SH rats. Before chlorothiazide, average urine Ca/creatinine (253 vs. 77.2) and cyclic AMP (26.6 vs. 13.4 mumol/mg creatinine, P < 0.001) on days 7 and 8 of the Ca-deprived diet were higher than the normal. On days 6 and 7 of chlorothiazide, average cyclic AMP (cAMP) excretion fell to normal range (11.7 vs. 12.7 mumol/mg creatinine) as Ca excretion was reduced to normal (62 vs. 59.4 mug Ca/mg creatinine). WE CONCLUDE: (a) SH, as defined in this study, is an inheritable biochemical marker and renal in origin. (b) The hypercalciuria is independent of parathyroid hormone, changes in plasma Ca and tubular handling of Na. (c) As studied in the PTX and volume expanded conditions of our experiments, decreased Ca reabsorption in superficial proximal convoluted tubule is demonstrable, but the hypercalciuria is probably mediated by diminished Ca transport by the deep nephron. The unlikely possibility of increased secretion by the terminal nephron, however, remains to be excluded. (d) In normal rats, there is internephron heterogeneity in regard to Ca transport during saline loading.
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PMID:Tubular mechanism for the spontaneous hypercalciuria in laboratory rat. 628 72

Hypercalcemia, hypercalciuria, and hyperphosphaturia were present in female dogs with adenocarcinomas derived from apocrine glands of the anal sac (CA). Remission of hypercalcemia accompanied tumor excision in all six dogs undergoing surgery, whereas tumor recurrence or growth of metastases was associated with a return of hypercalcemia. Preoperatively, the plasma concentrations of immunoreactive parathyroid hormone in all dogs were undetectable or in the low normal range. Plasma concentrations of 13,14-dihydro-15-keto-prostaglandin E2 (PGE2M) and serum 1,25-dihydroxyvitamin D were not significantly different from control dogs. Urinary cyclic AMP and hydroxyproline were increased in dogs with CA. No immunoreactive parathyroid hormone was detected in extracts from tumor tissue, and parathyroid glands from dogs with CA had ultrastructural characteristics of secretory inactivity. Lumbar vertebrae from hypercalcemic dogs had decreased trabecular bone volume and increased osteoclastic bone resorption compared with age-matched control dogs. After tumor excision, serum total calcium returned to the normal range, whereas immunoreactive parathyroid hormone increased 2- to 20-fold and 1,25-dihydroxyvitamin D decreased 2- to 8-fold. Postoperative hypocalcemia was not observed. These results indicate that CA produces a hypercalcemic factor other than immunoreactive parathyroid hormone or prostaglandin E2 that increases osteoclastic osteolysis distant from the tumor and results in hypercalcemia, hypercalciuria, and hyperphosphaturia.
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PMID:Hypercalcemia in dogs with adenocarcinoma derived from apocrine glands of the anal sac. Biochemical and histomorphometric investigations. 630 May 51

A 14 year old boy with essential signs of the tricho-rhino-phalangeal syndrome type II (Langer-Giedion-Syndrome) showed multiple areas of osteolysis as well as nephrolithiasis of the left kidney. Urine analysis revealed hypercalciuria and a lacking excretion of c-AMP. Following the Ellsworth-Howard-Test (200 U parathyroid hormone i.v.) neither the phosphate excretion increased nor c-AMP could be detected. The present results are in accordance with an isolated insensitivity of the kidney to parathyroid hormone on one hand and a regulatorily caused hyperparathyroid response on the other with ensueing hypercalciuria and nephrolithiasis.
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PMID:[Pseudohypohyperparathyroidism with the phenotype of the tricho-rhino-phalangeal syndrome]. 630 96

Ninety-seven male patients with idiopathic calcium urolithiasis and 17 normal male subjects were studied to evaluate the mechanism of idiopathic hypercalciuria with an oral calcium tolerance test, which has been useful in differentiating hypercalciuria. The changes in parathyroid function, such as parathormone and urinary cyclic AMP, and calcium after calcium load differed between absorptive hypercalciuria and renal hypercalciuria. We have confirmed that the change in serum calcitonin after calcium load was also different in these two hypercalciurias. The increase in serum calcium was sufficient to reduce parathyroid function but serum calcitonin was unchanged after calcium load in the control group, in patients with normocalciuria, and those with renal hypercalciuria. Although serum and urinary calcium were more elevated in absorptive hypercalciuria than in the other three groups, parathyroid function was not significantly reduced after loading in absorptive hypercalciuria. In this group only, the serum calcitonin was significantly elevated after calcium load. It is reasonable to suggest that, in this group, because parathyroid function is usually suppressed by intestinal hyperabsorption of calcium, parathyroid function may not be further suppressed by even calcium load. Possibly the significant stimulation of calcitonin may compensate for the lack of suppression of parathyroid function and maintain normal serum calcium levels in absorptive hypercalciuria. These results suggest that the change in serum calcitonin is also useful to differentiate abnormalities of calcium metabolism in patients with hypercalciuria.
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PMID:Oral calcium tolerance test and serum calcitonin in calcium stone formers. 630 68

The authors propose to study parathyroid hormone receptors in humans by means of a test "inspired by the Ellsworth-Howard test" using the active synthetic 1-34 fragment of the hormone PTH-1-34. The use of this test in 44 patients (29 healthy subjects, 7 patients with idiopathic hypercalciuria 5 cases of Paget's disease, 1 patient with idiopathic hypoparathyroidism, 2 cases of basal cell nevus syndrome) who received different doses of this substance intravenously, revealed a marked dose-dependent stimulation of adenyl-cyclase as objectified by an increase in urinary excretion of cyclic AMP (AMPcU). Distal tubular calcium reabsorption was also significantly affected as demonstrated by a decrease in urinary calcium in the first hours following administration of the 1-34 fragment even in the case of idiopathic hypercalciuria. In comparison to the "classical" Ellsworth-Howard test, however, no significant urinary phosphate response was observed during the present test. Similarly, urinary hydroxyproline and phosphate and calcium blood levels remained stable. As the results obtained for the case of hypoparathyroidism demonstrate, this easily performed test is useful for valuating parathormone receptors in kidney by means of two sensitive parameters (AMPcU and the ratio of fractional urinary calcium to urinary creatinine). In addition to its action, synthetic fragment h PTH-1-34 offers the advantage of being totally innocuous.
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PMID:[The effects of synthetic 1-34 fragment of human PTH on kidney and bone receptors in man. Use of the Ellsworth-Howard test]. 631 80

Idiopathic calcium stone-formers with hypercalciuria during fasting have significantly lower urinary cyclic AMP levels (nmol/dl of glomerular filtrate) than fasting normocalciuric stone-formers. Female subjects, including both normal subjects and idiopathic calcium stone-formers, have higher urinary cyclic AMP levels than their male counterparts, and this difference is significant when urinary cyclic AMP is expressed in the units mumol/g of creatinine. Expressing urinary cyclic AMP in nmol/dl of glomerular filtrate reduces this difference but does not abolish it. Thus, in comparing urinary cyclic AMP levels in various subgroups of the calcium stone-formers and in normal subjects, both sex differences and the units of urinary cyclic AMP expression must be taken into consideration. The magnitude of the change in urinary cyclic AMP in response to an oral calcium load appears to depend on the antecedent urinary cyclic AMP excretion rate, whereby those individuals (either normal subjects or calcium stone-formers) having the highest urinary cyclic AMP levels demonstrate the greatest fall in urinary cyclic AMP after a calcium load.
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PMID:Urinary adenosine cyclic 3',5'-monophosphate in idiopathic calcium stone-formers: response to an oral calcium load. 631 71

We examined parathyroid gland function in 47 patients with idiopathic hypercalciuria in an effort to determine whether serum levels of parathyroid hormone (PTH) and/or urinary excretion of cyclic adenosine monophosphate (cyclic AMP) can discriminate between the various forms of hypercalciuria. Although we could separate our 47 patients into two groups, 21 patients with renal hypercalciuria (RH) and 15 patients with absorptive hypercalciuria (AH), there remained a group of 11 patients who did not exactly correspond to either group. Basal serum PTH was normal in the two groups: for RH, 10.32 +/- 0.93; for AH, 11.43 +/- 1.10 microliter Eq/ml. Similarly, urinary cyclic AMP did not differ between the two groups: for RH, 4.88 +/- 0.5; for AH, 4.87 +/- 0.55 nmoles/dl/min GFR. Moreover, the response of the parathyroid glands to acute hypocalcemia produced by intravenous infusion of EDTA was not different among patients with AH, RH, and control subjects. Only one patient showed a marked increase of serum PTH in response to acute hypocalcemia, and the bone biopsy revealed increased osteoclastic resorption. In conclusion, our data show that serum levels of PTH and urinary cyclic AMP do not differentiate between the various forms of idiopathic hypercalciuria. The EDTA test demonstrated that secondary hyperparathyroidism is very uncommon in these patients.
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PMID:Absence of secondary hyperparathyroidism in most patients with renal hypercalciuria. 633 Apr 24

Using an in vitro method, the uptake of radio-labelled Ca2+ by jejunal biopsy specimens from control subjects, patients with idiopathic hypercalciuria and patients with renal stones without hypercalciuria, were compared. Radio-labelled Ca2+ uptake was investigated over the concentration range 0.1-5.0 mmol/l. For all subjects there was a linear relationship between Ca2+ uptake and medium concentration suggesting that Ca2+ uptake was a passive process. There was no significant difference in Ca2+ uptake between control subjects and patients with renal stones without hypercalciuria. Patients with idiopathic hypercalciuria, both absorptive and renal subtypes, showed increased Ca2+ uptake at all incubation medium concentrations. Assays of various biochemical parameters including alkaline phosphatase, Ca2+-activated ATPase, cyclic AMP and Ca2+-binding protein, in jejunal biopsy specimens showed no significant differences between control subjects and patients with idiopathic hypercalciuria. The results suggest that the intestinal abnormality in idiopathic hypercalciuria is due to enhanced permeability of the brush border membrane to Ca2+, possibly mediated by alterations in membrane lipids.
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PMID:Studies on intestinal calcium absorption in patients with idiopathic hypercalciuria. 654 1

A group of 121 patients with a history of multiple or complicated calcium urolithiasis were divided into three subgroups: normal, absorptive and renal/resorptive calciuria by means of a calcium-loading test. Patients with renal hypercalciuria had lower bone mineral content (BMC) than the other groups but did not differ in amount of bone or TmPO4/GFR. The 24-hour urine calcium excretion was elevated in patients with renal and absorptive type of hypercalciuria but not in patients with normal calcium-loading test and there was no correlation to BMC. The c-AMP/creatinine seemed to discriminate patients with resorptive calciuria from patients with renal calciuria. It is suggested that only patients with renal hypercalciuria should be treated with calcium-retaining drugs such as thiazides.
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PMID:Calcium-loading test and bone disease in patients with urolithiasis. 665 69


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