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)

We have investigated an 18-yr-old hypercalciuric female with features of both renal hypercalciuria and pseudohypoparathyroidism. She had increased circulating parathyroid hormone levels, which are common to both diseases. She also had a modest hypocalcemia and low normal basal cAMP excretion, both of which are more likely to occur in pseudohypoparathyroidism. She also had Albright's osteodystrophy, which is frequent in patients with pseudohypoparathyroidism and has never been reported in patients with renal hypercalciuria. In contrast to patients with pseudohypoparathyroidism, her serum 1,25-dihydroxycholecalciferol level was increased and her renal responses to parathyroid hormone infusion, including renal calcium reabsorption, were normal. This patient, therefore, raises the possibility that some patients with renal hyperalciuria may have a forme fruste of pseudohypoparathyroidism.
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PMID:Albright's osteodystrophy in a patient with renal hypercalciuria. 22 62

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 stimulation of cyclic AMP production by human renal cortical membranes in the presence of the GTP analogue 5'-guanylimidodiphosphate and a calcium chelator represents a homologous assay system for the evaluation of biologically active parathyroid hormone (bioPTH) in human serum. Bioactive PTH was raised above normal (normal range: undetectable to 4.6 pmol human PTH(1-34) per 1) in 13/17 (76%) patients with primary hyperparathyroidism, in 5/6 (83%) patients with surgically proven hyperparathyroidism secondary to chronic renal failure, in 4/5 (80%) patients with hyperparathyroidism secondary to hypocalcaemia, in all three patients with pseudohypoparathyroidism, in 5/17 (29%) patients with osteoporosis and in 1/9 (11%) patients with renal stones and/or hypercalciuria. Bioactive PTH correlated positively with immunoreactive PTH (iPTH) measured with a radioimmunoassay predominantly recognizing the middle- and carboxyl-terminal region of the PTH molecule (r = 0.503, P less than 0.001). A positive correlation (r = 0.572, P less than 0.05) was found between values of serum calcium and bioPTH in the group with primary hyperparathyroidism. Immunoreactive PTH did not correlate significantly with calcium in this group. In the other patients except those who had chronic renal failure, a negative correlation between serum calcium and both bioPTH and iPTH was observed (P less than 0.01). When alkaline phosphatase was compared with bioPTH in all patients, the correlation was positive (r = 0.390, P less than 0.01); no significant correlation existed between iPTH and alkaline phosphatase in the patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal adenylate cyclase assay for biologically active parathyroid hormone: clinical utility and physiological significance. 394 39

Vitamin D topical analogues are now considered an excellent adjunct to the therapy of psoriasis. Systemic vitamin D3 treatment has been used occasionally, especially in case of associated hypocalcemia. We report five patients (aged 6, 16, 36, 58 and 79 years) successfully treated with vitamin D3 per os. Four had erythrodermic and/or pustulous psoriasis, and two of these had concomitant hypocalcemia. The fifth patient was a girl with pseudohypoparathyroidism and psoriasis vulgaris. The association of hypocalcemia and severe psoriasis is classical and was an incentive to try vitamin D treatment. A review of the literature showed that vitamin D can also be reported as a treatment of psoriasis vulgaris. Hypercalciuria and hypercalcemia are limiting risks. However calcium toxicity seems to be minor when vitamin D is given once a day at bedtime in doses lower than 2 micrograms/24 h. Double blind studies should be performed to determine the real efficacy of this treatment.
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PMID:[Treatment of psoriasis by oral calcitriol. A study of 5 cases and review of the literature]. 783 59

Pseudohypoparathyroidism (PHP) is a rare inherited syndrome characterized by parathyroid hormone (PTH) resistance and is frequently associated with Albright's hereditary osteodystrophy and resistance to other cAMP-mediated hormones. The usual neonatal presentation is mild primary hypothyroidism secondary to resistance to thyroid-stimulating hormone; hypocalcemia usually develops after age 3-5 years. This work describes the diversity in the clinical expression and course of PHP, with emphasis on calcium levels by age and treatment, in 8 children under long-term follow-up at our pediatric tertiary center. The calcium levels at presentation ranged from transient neonatal hypocalcemia to infantile hypercalcemia to childhood/adolescence hypocalcemia. Interestingly, relative hypocalciuria at diagnosis and during therapy, in the presence of renal PTH resistance, was the rule. These findings indicate that transient neonatal hypocalcemia associated with other clinical features or a family history of PHP may be a flag for clinicians to screen for PTH resistance later in life. In addition, PTH resistance may be missed by surveying calcium levels only; thus the PTH levels have to be checked as well. In addition, the recommendation for patients with hypoparathyroidism that strict low-normal calcium levels be maintained during therapy in order to prevent hypercalciuria is probably not applicable in PHP.
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PMID:Clinical heterogeneity of pseudohypoparathyroidism: from hyper- to hypocalcemia. 1866 13