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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute hypercalcemia in the conscious, unanesthetized rat, achieved by a 30-minute infusion of CaCl2 (serum calcium level, 12.8 +/- 0.6 mg/dl) resulted in significant elevation of mean arterial pressure (from 112 +/- 2 mm Hg to 129 +/- 3 mm Hg, p less than 0.001). This pressor response was associated with a significant increase in systemic vascular resistance, from 0.45 +/- 0.02 mm Hg/(ml/min)/kg body weight to 0.50 +/- 0.02 mm Hg/(ml/min)/kg body weight (p less than 0.05), but it caused no alteration in cardiac index. The pressor response to acute hypercalcemia does not appear to be mediated by vasopressor hormones or attenuated by vasodepressor hormones since inhibition of the renin-angiotensin system (nephrectomy), catecholamines (central and peripheral 6-hydroxydopamine), vasopressin (vascular antagonist), prostaglandins (indomethacin), and parathyroid hormone (parathyroidectomy) did not significantly alter the pressor response to infusion of CaCl2 in spite of similar serum calcium levels in all groups of animals. Rather, the pressor response to acute hypercalcemia seems to be mediated by a direct action of calcium ion on smooth muscle and perhaps myocardial cell contractility, since pretreatment with the calcium channel blockers verapamil or nifedipine blocked the pressor response to acute hypercalcemia.
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PMID:Mechanism of acute hypercalcemic hypertension in the conscious rat. 407 24

A possible association between the impairment of urinary concentrating ability and an impairment of the vasopressin-dependent cyclic AMP system in hypercalcemia was investigated in rat kidneys both in vivo and in vitro. The increases of urinary osmolality and negative free water clearance and the increase of urinary cyclic AMP excretion by vasopressin injection were significantly less in the hypercalcemic rats than in the control rats. The increase of cyclic AMP concentration by vasopressin in renal medullary tissue was significantly less in the slices obtained from the hypercalcem'c rats than in those obtained from the control rats. The activation of adenylate cyclase by vasopressin was significantly less in the group with an increased concentration of calcium in media than the control group, but phosphodiesterase activity was not affected by calcium concentration in the media. These data suggest that the impaired urinary concentrating ability in hypercalcemic kidneys is due at least in part to the direct inhibitory effect of calcium on the vasopressin-dependent cyclic AMP system at the level of adenylate cyclase in renal medulla.
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PMID:Pathogenic role of cyclic AMP in the impairment of urinary concentrating ability in acute hypercalcemia. 437 61

In an unselected series of 185 patients with histologically confirmed bronchial carcinoma 16 had endocrine disturbances attributable to the tumour (excluding pulmonary osteoarthropathy). Of these, 11 patients had hypercalcaemia; three inappropriate secretion of antidiuretic hormone; one Cushing's disease; three hypertrophic osteoarthropathy; and one gynaecomastia. Cushing's disease and inappropriate antidiuresis are specifically associated with oat-cell tumours, and hypercalcaemia occurs most frequently with squamous carcinoma. A negative correlation exists between gynaecomastia and osteoarthropathy on the one hand and oat-cell carcinoma on the other.
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PMID:Endocrine and metabolic disordes in bronchial carcinoma. 548 22

Pulmonary cancers produce many hormonal polypeptides. There is a tumor-specific pattern to the appearance of abnormal adrenal function and inappropriate secretion of vasopressin, which are frequently found in small cell undifferentiated carcinoma but occur only very rarely, if at all, in squamous tumors. Humoral hypercalcemia, on the other hand, occurs almost entirely in squamous tumors and is rarely if ever seen in small cell or large cell tumors or in adenocarcinoma. In contrast, "big ACTH" and beta lipotropin are found in the plasma and tumor extracts of lung cancers of all types. Calcitonin and the beta chain of human chorionic gonadotropin are also found in the plasma of a considerable portion of patients with all histological types of lung cancers.
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PMID:The pattern of ectopic hormone production in lung cancer. 627 Sep 16

Plasma vasopressin was measured by radioimmunoassay in eight normal subjects and in six patients with hypercalcaemia. Vasopressin levels were significantly elevated in the hypercalcaemic patients, although urine osmolalities were lower than in controls. This finding is consistent with a renal resistance to the action of endogenous vasopressin in hypercalcaemia.
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PMID:Plasma vasopressin in hypercalcaemic states. 657 45

A number of advances which took place during the last decade have increased our understanding of the physiology and pathophysiology of urinary concentrating defects. The development of a highly sensitive radioimmunoassay for plasma vasopressin concentration has shed new light on vasopressin control mechanisms. The cellular action of vasopressin in biological membranes has been studied by various techniques. The role of adenylate cyclase, cyclic adenosine monophosphate (cAMP), microtubules, and microfilaments, in the response of vasopressin-sensitive membranes is now partially understood. New models of countercurrent multiplication systems, in which urea plays a prominent role, offer a better explanation of certain experimental facts. Such advances had permitted a better understanding of clinical conditions characterized by concentrating defects, including hyperkalemia, hypercalcemia, parenchymal renal disease, obstructive renal disease, and polyuria induced by certain drugs.
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PMID:Pathophysiology of renal concentrating defects. 679 72

In outlining the pathology of various electrolyte metabolism abnormalities in cancer patients we considered the main clinical points between pathologies and emergency treatment. In regard to sodium (Na+) metabolism, one pathologic state that requires our attention is hypernatremia. Hypernatremia is accompanied with dehydration and is due to water loss, vomiting, diarrhea and renal insufficiency. One of the major causes of this condition is lack of the antidiuretic hormone due to intracranial metastasis of the tumor. When hypernatremia becomes severe, it is accompanied with circulatory failure, muscular asthenia, disorientation, convulsions, coma and other cerebral symptoms. Treatment consists of replenishing the water content by infusion of electrolyte solutions which should be carefully conducted after complete diagnose of the severity of the patient's pathological condition. Hyponatremia, like sick cell syndrome, is observed relatively frequently in cancer patients. When the serum Na level falls markedly, it induces cerebral edema and causes disorders of consciousness. The major treatment consists of providing both water and sodium supplements. Hyperkalemia is observed at the time of renal insufficiency, tissue lesions, vomiting, and diarrhea. When serum potassium level rises, it causes bradycardia, ventricular fibrillation, or cardiac arrest. It is important to diagnostically apprehend the severity of this condition using EKG and determining the serum K1+ level. For emergency treatment injection of calcium gluconate is very effective. Hypokalemia is often manifested by the loss of intestinal fluids due to diarrhea or during administration of diuretic agents. Clinical symptoms include neural paralysis but emergencies occur relatively infrequently. K C1 injections are used in treating this condition. Hypercalcemia is manifested in cancer patients during hyperparathyroidism. Its clinical symptoms include lassitude, tachycardia, nausea, vomiting, and renal dys-function, leading to neural symptoms in severe cases. The main treatment consists of injection of physiological saline solution and administration of calcitonin, mithramycin. Hypocalemia is manifested during renal insufficiency, lack of vitamin D, and hypothyroidism. In classic cases it causes tetanic spasms. Injection of calcium is an effective treatment but since during tetanic spasms alcalosis may easily occur, treatment should only be provided after obtaining a complete understanding of the patient's condition. The pathological conditions described above can not be said to specific to cancer but it should be kept in mind that one of their main causative factors is the involvement of mechanism which produces ectopic hormones from cancerous tissues.
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PMID:[Electrolyte metabolism and emergency]. 688 72

The present experiments examined the role of prostaglandin biosynthesis in the increase in urine flow rate seen in rats with hypercalcemia induced by the administration of 1,25-dihydroxycholecalciferol. In a first group, rats receiving the vitamin D metabolite developed hypercalcemia, polyuria, and increased urine prostaglandin E excretion. Indomethacin resulted in a fall in urine prostaglandin E excretion. A second group was fluid restricted to ascertain whether increased thirst could be an etiologic mechanism of the polyuria. This resulted in a trivial fall in urine flow rate despite a fall in body weight and a rise in both urine and plasma osmolality. In a final group, prostaglandin inhibition restored the vasopressin sensitivity of the hypercalcemic kidney. Accordingly, the polyuria seen in hypercalcemic rats after the administration of 1,25-dihydroxycholecalciferol is associated with an increase in urine prostaglandin E excretion and can be reversed by inhibition of prostaglandin synthesis. In addition, this polyuria can occur independent of the thirst mechanism. Finally, there is evidence that the vasopressin resistance of the hypercalcemic kidney could be reversed by prostaglandin inhibition.
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PMID:Prostaglandin-dependent polyuria in hypercalcemia. 689 50

The effect of interaction between calcium and prostaglandin (PG) on the action of antidiuretic hormone (ADH) was studied in the water-diuresing anesthetized dog. Maximal urinary osmolality after 100 mU or ADH was 331 +/- 24 in the normocalcemic state versus only 228 +/- 31 mosmol/kg (P less than 0.01) in dogs made acutely hypercalcemic when their serum Ca concentration was increased from 8.9 +/- 0.2 to 11.6 +/- 0.4 mg/100 ml (P less than 0.001). To define the role of PG in this effect, studies were performed in the presence of PG inhibition with indomethacin (10 mg/kg). The antidiuretic response to 100 mU of ADH was decreased by hypercalcemia, as maximal osmolality was 1,096 +/- 65 in the normocalcemic PG-inhibited dog but only 555 +/- 50 mosmol/kg in the acutely hypercalcemic PG-inhibited dog (P less than 0.001). Conversely, the effect of PG inhibition to enhance the hydroosmotic effect of ADH was also demonstrable in acutely hypercalcemic dogs, as maximal urinary osmolality following 100 mU of ADH was 257 +/- 9 before and 557 +/- 60 mosmol/kg after PG inhibition (P less than 0.001). These studies demonstrate, therefore, that the effect of acute hypercalcemia on the hydroosmotic response to vasopressin is not dependent on the synthesis of an endoperoxide metabolite. Likewise, hypercalcemia blunts but does not abolish the effect of PG inhibitors to potentiate the hydroosmotic effect of ADH.
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PMID:Calcium-prostaglandin interaction on the action of antidiuretic hormone in the dog. 706 41

Vasopressin function and thirst were studied in fourteen hypercalcaemic patients (ten hyperparathyroid and four disseminated malignant disease). Ten patients had decreased renal concentrating ability which reversed within a few days in the majority of patients whose hypercalcaemia was corrected by parathyroidectomy. Although eight patients complained of thirst, none showed a lowered threshold of thirst appreciation during hypertonic saline infusion. Osmoregulation of vasopressin secretion was not reduced in any patient, but the hyperparathyroid group had an exaggerated vasopressin response to osmotic stimulation. We conclude that a partial, reversible nephrogenic diabetes insipidus occurs in at least 70% of hypercalcaemic patients irrespective of cause, which accounts for the polyuria induced by hypercalcaemia.
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PMID:Vasopressin function in hypercalcaemia. 731 89


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