Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Familial hypocalciuric hypercalcemia (FHH) is usually characterized by asymptomatic hypercalcemia, mild hypermagnesemia, and low urinary calcium excretion, and is occasionally associated with pulmonary fibrosis. It is inherited as an autosomal-dominant, and no sporadic case of hypocalciuric hypercalcemia has been heretofore reported. This report describes a patient with hypocalciuric hypercalcemia completely compatible with FHH but with no family history, suggesting that the most likely diagnosis is "nonfamilial" hypocalciuric hypercalcemia. We propose that the urinary excretion of calcium be examined in all patients with hypercalcemia, hypophosphatemia, and increased PTH before neck surgery, even if patients have no family history of hypercalcemia.
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PMID:A case of hypocalciuric hypercalcemia without family history. 182 36

Familial hypocalciuric hypercalcemia (FHH) or familial benign hypercalcemia is an autosomal dominant inherited disorder of calcium metabolism. It is characterized by lifelong asymptomatic hypercalcemia associated with a relative hypocalciuria and a tendency to hypermagnesemia. The biochemical features of this disorder are difficult to distinguish from mild primary hyperparathyroidism. Several patients have therefore been operated upon for hyperparathyroidism with no effect on calcium levels. The most important diagnostic criterion of FHH in a single individual is the demonstration of asymptomatic hypercalcemia in other family members including children. The pathophysiology of the disorder is unknown. A genetic defect of cellular calcium transport leading to a disturbed regulation of extracellular calcium by parathyroid glands and kidneys has been suggested. The hypercalcemia in this disorder is asymptomatic, usually without complications and does not require treatment. Partial parathyroidectomy has no effect on the hypercalcemia. However, it is important to diagnose this condition in order to avoid unnecessary neck explorations. Two complications have been described in some families: pancreatitis and neonatal primary hyperparathyroidism. The recommended management of these complications is total parathyroidectomy.
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PMID:[Familial hypercalciuric hypercalcemia]. 203 54

Four families with familial hypocalciuric hypercalcaemia were studied. The probands presented with abdominal pain, which in three was due to acute pancreatitis; in two the condition was life threatening. Serum concentrations of calcium, magnesium, phosphate, and immunoassayable parathyroid hormone, urinary calcium excretion, and the rate of renal tubular reabsorption of phosphate were measured; the findings were compared with results in 10 patients with primary hyperparathyroidism matched for serum calcium concentration to establish differences between the diseases. Familial hypocalciuric hypercalcaemia should be suspected in patients with hypercalcaemia in whom daily urinary calcium excretion is below 5 mmol (200 mg) provided renal insufficiency, vitamin D deficiency, and ingestion of drugs that reduce calcium excretion have been excluded. Most cases appear to run a benign course, but some may suffer considerable morbidity. Surgical treatment should be reserved for patients with severe complications, when all parathyroid tissue should be removed.
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PMID:Familial hypocalciuric hypercalcaemia and acute pancreatitis. 678 29

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant trait comprising hypercalcemia, hypophosphatemia, parathyroid hyperplasia, and unusually low renal clearance of calcium. We evaluated the role of parathyroid hormone in the relative hypocalciuria of FHH and characterized the renal transport of calcium in this disorder using three previously hypercalcemic FHH patients with surgical hypoparathyroidism and three controls with surgical hypoparathyroidism. Intravenous infusion of calcium chloride in two patients with FHH and in three controls increased serum calcium from a mean basal of 5.0 to a mean peak of 6.8 meq/liter in two FHH patients and from 4.2 to 5.7 in three control subjects. Urinary calcium in a third FHH patient was studied without calcium infusion during recovery from hypercalcemia of vitamin D intoxication. At all serum concentrations of calcium, calcium clearance was lower in FHH than in controls; at base-line serum calcium, the ratio of calcium clearance to inulin clearance (C(Ca)/C(IN)) in FHH subjects was 32% of that in controls and decreased to 19% during hypercalcemia. Calcium infusion increased the ratio of sodium clearance to inulin clearance in controls from a base line of 0.020 to 0.053 at peak concentrations of calcium in serum, but did not affect this parameter in FHH (0.017 at base-line serum calcium vs. 0.019 at peak). When calcium infusion studies were performed (in two patients with FHH and one control) during administration of acetazolamide, a drug whose principal renal action causes inhibition of proximal transport of solute, C(Ca)/C(IN) in the patients with FHH was 29 and 7% of that of the control at base-line and peak serum calcium, respectively. In contrast, ethacrynic acid, a diuretic that acts in the ascending limb of the loop of Henle, increased C(Ca)/C(IN) more in the FHH patients than in the control subject; C(Ca)/C(IN) was 65% at base-line and 47% at peak serum calcium, compared with that of the control subject. The greater calciuric response to ethacrynic acid than to acetazolamide or calcium infusion alone in FHH indicates that a major renal locus of abnormal calcium transport in this disorder may be the ascending limb of the loop of Henle.Decreased clearance of calcium in patients with FHH and hypoparathyroidism when compared with hypoparathyroid controls indicates that relative hypocalciuria in FHH is not dependent on hyperparathyroidism. Since the parathyroid glands in FHH are not appropriately suppressed by calcium, this implies that FHH represents a disorder of abnormal transport of, and/or response to, extracellular calcium in at least two organs, parathyroid gland and kidney.
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PMID:Urinary calcium excretion in familial hypocalciuric hypercalcemia. Persistence of relative hypocalciuria after induction of hypoparathyroidism. 687 59

Familial hypocalciuric hypercalcemia (FHH) is generally characterized by lifelong hypercalcemia without hypercalciuria and is inherited in an autosomal dominant manner. Affected individuals show abnormal parathyroid and renal responses to changes in the extracellular calcium concentration. A Japanese FHH family was screened for mutations in the Ca(2+)-sensing receptor gene by the polymerase chain reaction and single strand conformation polymorphism. The proband with hypercalcemia showed an abnormal pattern in exon 1 of the gene, whereas her two sisters with normocalcemia showed a normal pattern. The consanguineous parents with borderline serum calcium concentrations showed both patterns. Nucleotide sequence analysis identified a G-->C point mutation at nucleotide 118 that resulted in the conversion of the normal codon for proline into a codon for alanine at amino acid 40 (numbered according to the bovine complementary DNA). The proband was homozygous for the mutation, and the parents were heterozygous. These results imply that this mutation in the human Ca(2+)-sensing receptor gene causes FHH and that the dosage of the gene defect determines disease phenotype.
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PMID:Familial hypocalciuric hypercalcemia associated with mutation in the human Ca(2+)-sensing receptor gene. 767

Familial hypocalciuric hypercalcemia (FHH) is characterized by lifelong asymptomatic hypercalcemia without PTH hypersecretion and is inherited as an autosomal dominant trait with near 100% penetrance. In contrast, neonatal severe hyperparathyroidism (NSHPT) is a life-threatening disorder characterized by marked hypercalcemia and PTH hypersecretion. FHH/NSHPT results from inactivating mutations of the human calcium-sensing receptor (Casr) gene on chromosome 3q13.3-24. Nearly 30 different mutations of the Casr gene associated with FHH/NSHPT have been reported previously. In this report, genetic analysis of 1 Japanese NSHPT family revealed 2 novel mutations at codon 185 (CGA-->TGA/Arg-->Ter) in exon 4 of the Casr gene and at codon 670 (GGG-->GAG/Gly-->Glu) in exon 7. The Arg185Ter change was shown to occur in the proband's unaffected father and paternal grandmother as well as in the proband. The other mutation in exon 7 was shown in the proband's unaffected mother of Philippine origin as well as in the proband. This family is the first case of manifestation of more than 1 mutation in a proband's chromosomes; 1 mutation was obtained from the unaffected father, and the other was from the unaffected mother. Our observations have given us important keys to help elucidate the structure-function relationships of the Casr.
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PMID:Two novel missense mutations in calcium-sensing receptor gene associated with neonatal severe hyperparathyroidism. 925 59

The ability of parathyroid cells to recognize and respond to (i.e., "sense") small changes in the extracellular Ca2+ concentration (Ca2+o) plays a crucial role in mineral ion homeostasis. Expression cloning in Xenopus laevis oocytes enabled isolation of a cDNA coding for the bovine parathyroid CaR. CaRs were later isolated from human parathyroid and kidney, rat kidney, brain and C-cell, rabbit kidney, and chicken parathyroid. All are tissue and species homologs of the same ancestral gene. The predicted CaR protein has a large extracellular amino-terminus, which binds polycationic CaR agonists; a central core with seven membrane-spanning helices, documenting that it is a G protein-coupled receptor; and an approximately 200 amino acid carboxyl-terminal tail. The CaR is highly expressed in parathyroid and C-cells, along almost the entire nephron and gastrointestinal (GI) tract and within numerous regions of the brain, particularly hippocampus, cerebellum, and hypothalamus. The CaR's physiological importance has been documented by the identification of hyper- and hypocalcemic syndromes due to inactivating or activating CaR mutations, respectively. Familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT) are caused by loss-of-function CaR mutations producing Ca2+o "resistance," while autosomal dominant hypocalcemia is the result of activating mutations rendering CaRs overly sensitive to Ca2+o. In addition to showing altered parathyroid responsiveness to Ca2+o, patients with FHH reabsorb too much urinary Ca2+ and Mg2+ at a given Ca2+o, while those with autosomal dominant hypocalcemia excrete too much, illustrating the CaR's key role in renal handling of divalent cations. Recent in vitro data suggest that the CaR directly regulates renal water handling in the collecting duct. Indeed, patients with FHH concentrate their urine normally, despite their hypercalcemia, while those with autosomal dominant hypocalcemia can exhibit impaired urinary concentration at normal or even low Ca2+o, suggesting that the CaR enables coordination of renal calcium and water handling. In addition to serving these "homeostatic" roles, the CaR likely also enables Ca2+o to serve additional roles as an extracellular messenger. The receptor regulates key Ca2+ and K(+)-permeable ion channels in hippocampal and other brain cells and likely senses local changes in Ca2+o within the brain microenvironment accompanying neuronal activation. It is also present in and regulates ion channels in lens epithelial cells, potentially playing some role in cataract development in hypoparathyroid patients. In keratinocytes and epithelial cells of the gastrointestinal tract, in contrast, the CaR may regulate cellular proliferation and differentiation, processes known to be modulated by Ca2+o in these cell types. Thus, in addition to sensing and regulating systemic Ca2+o, the CaR likely enables Ca2+o to act as a local signal for cells within specific microenvironments, such as the brain or eye.
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PMID:The calcium-sensing receptor (CaR) permits Ca2+ to function as a versatile extracellular first messenger. 976 11

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant disorder characterized by high penetrance of relatively benign, lifelong persistent hypercalcemia and hypocalciuria. By contrast, neonatal severe hyperparathyroidism represents a life-threatening form of hypercalcemia that can cause the early newborn mortality if immediate intervention is not undertaken. Both disorders are due to inactivation mutation of the human calcium-sensing receptor (CaSR) gene on chromosome 3q21-24. Up to now, more than 30 mutations in the CaSR gene associated with FHH have been described. In this study, we analyzed one 79-yr-old male with hypocalciuric hypercalcemia without siblings or children to compare with an additional group of 50 normal Chinese subjects in Taiwan. DNA sequence analysis of the CaSR gene was performed. The result showed that the proband had a heterozygous nonsense mutation in exon 7 of the CaSR gene at codon 648 (CGA-->TGA/Arg-->Ter). This mutation, located in the COOH-terminal of the first intracellular loop of the CaSR, predicts a markedly truncated protein. We have identified a novel R648X mutation in the CaSR gene in one patient with FHH in Taiwan
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PMID:A novel mutation in the calcium-sensing receptor gene in a Chinese subject with persistent hypercalcemia and hypocalciuria. 1123 70

Familial hypocalciuric hypercalcemia is said to be an extremely rare condition but is clinically important because it can be confused with primary hyperparathyroidism. The biochemical features of the two conditions are similar, but the former is benign while the latter can have serious clinical consequences with patients occasionally proceeding to parathyroidectomy. It is therefore important to differentiate accurately between the two. With this in mind it would be useful to know the prevalence of familial hypocalciuric hypercalcemia when considering the differential diagnosis of primary hyperparathyroidism. However, as far as we are aware, no estimate of the prevalence of this condition can be found in the literature. We describe how an estimate was made of the prevalence of familial hypocalciuric hypercalcemia in the west of Scotland. We estimate the prevalence to be 1 in 78,000 at least.
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PMID:The prevalence of familial hypocalciuric hypercalcemia. 1201 64

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant disease characterized by mild hypercalcemia, an inappropriately high parathyroid hormone level, and absence of hypercalciuria. Heterozygous inactivating mutations of calcium-sensing receptor (CaSR) are found in about two thirds of patients with FHH. Histologic examination of parathyroid glands in FHH is reported to show normal histology or chief cell hyperplasia. Thus, histologic features of the parathyroid glands in FHH vary, and there is no clear histologic criterion that indicates FHH. The authors have encountered three hypercalcemic patients with characteristic histologic features of enlarged parathyroid glands. Clusters of parenchymal cells were mixed with fat cells, and the area of fat cells was 33% to 49% of the total area. These features are similar to those described as parathyroid lipohyperplasia. Postoperative evaluation showed that fractional excretion of calcium was low in these patients. Direct sequencing of the polymerase chain reaction product showed that the first patient was heterozygous for an already reported inactivating mutation of CaSR (P55L). The second patient was also heterozygous for a novel inactivating mutation (R220W). The third was homozygous for an inactivating mutation (Q27R). These results indicate that histologic features of parathyroid lipohyperplasia suggest the presence of inactivating mutations of CaSR.
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PMID:Inactivating mutations of calcium-sensing receptor results in parathyroid lipohyperplasia. 1176 15


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