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)

Recent information on the pathophysiology and treatment of hypercalcemia of malignancy is reviewed, and the roles of two new agents, gallium nitrate and pamidronate, are discussed. Current evidence suggests that parathyroid hormone-related protein is the most important mediator of humoral hypercalcemia of malignancy. In patients with local osteolytic hypercalcemia, cytokines have been implicated as mediators. Effective treatment of hypercalcemia of malignancy may improve patients' quality of life, although an episode of hypercalcemia is a poor prognostic indicator for survival. Gallium nitrate is more effective than salmon calcitonin and possibly more effective than etidronate in the treatment of hypercalcemia of malignancy. The primary adverse effect of gallium nitrate is nephrotoxicity, and its use must be avoided in patients who have renal dysfunction or who are receiving nephrotoxic drugs. Pamidronate is more effective than etidronate in the treatment of hypercalcemia of malignancy and can be administered as a single i.v. dose. The adverse effects of pamidronate include mild fever, hypocalcemia, and hypophosphatemia. Compared with gallium nitrate, pamidronate offers a more convenient dosing regimen, is less frequently associated with nephrotoxicity, and is less expensive. Single i.v. doses of either pamidronate or plicamycin effectively lower serum calcium levels and are reasonable choices for maintenance therapy. Gallium nitrate and pamidronate may be slightly more effective than previously available agents for initial treatment of hypercalcemia. Pamidronate currently offers the best combination of effectiveness, ease of administration, and a low rate of adverse effects.
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PMID:Update on the medical treatment of hypercalcemia of malignancy. 845 60

Humoral hypercalcemia of malignancy (HHM) results from the production of PTH-related protein (PTHrP) by human tumors. One previous study has reported the results of human (h) PTHrP(1-34) infusion into humans. In that report, hPTHrP(1-34) was found to be qualitatively similar to but 3- to 10-fold less potent than hPTH(1-34). Because hPTHrP(1-36) and not hPTH(1-34) is likely to be the actual amino-terminal secretory form of PTHrP, and because this previously reported lack of potency was unexpected, we repeated these studies using hPTHrP(1-36) and compared the results with those obtained with hPTH(1-34). Healthy subjects (n = 30) were infused over 6 h with either vehicle alone, hPTH(1-34) at a dose of 8 pmol/kg.h, or hPTHrP(1-36) at doses of 8 or 80 pmol/kg.h. Both hPTH(1-34) and hPTHrP(1-36) caused an increase in serum ionized calcium, a decrease in serum phosphorus, an increase in the fractional excretion of phosphorus, a decrease in the tubular maximum for phosphorus, an increase in nephrogenous cAMP excretion, and suppression of endogenous PTH(1-84). Unlike events observed in HHM, hPTHrP(1-36) induced an increase in plasma 1,25-dihydroxyvitamin D2. In addition, fractional excretion of calcium was reduced by both hPTH(1-34) and hPTHrP(1-36). In their actions on serum calcium, renal calcium and phosphorus handling, and nephrogenous cAMP excretion, hPTHrP(1-36) and hPTH(1-34) appeared equivalent in potency. These studies indicate that short-term infusion of hPTHrP(1-36) into humans reproduces most but not all of the features of HHM. In contrast to the reported findings with hPTHrP(1-34), we found the potency of hPTHrP(1-36) to be comparable with that of hPTH(1-34) in vivo in humans. In addition, unlike the situation in HHM, hPTHrP(1-36) produces an increment in plasma 1,25-dihydroxyvitamin D2. Finally, hPTHrP(1-36) has been shown for the first time to have anticalciuric effects in humans. This would suggest that, in addition to osteoclastic bone resorption, tubular reabsorbtion of calcium by hPTHrP may contribute to the hypercalcemia in patients with HHM.
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PMID:Parathyroid hormone (PTH)-related protein(1-36) is equipotent to PTH(1-34) in humans. 855 Jul 52

It has become recently appreciated that the hypercalcemia of malignancy is commonly caused by the increased production of parathyroid hormone-related protein (PTHrP) by the cancer. In fact, the demonstration of increased PTHrP production in a patient with hypercalcemia is regarded as pathognomonic of malignancy. The authors describe a patient with a benign ovarian lesion that produced PTHrP and caused hypercalcemia. They identify other reports of hypercalcemia associated with hypercalcemia and benign tumors, and refer to this syndrome as the humoral hypercalcemia of benignancy. Although apparently rare, a benign PTHrP-producing tumor should be considered in the differential diagnosis of hypercalcemia.
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PMID:The humoral hypercalcemia of benignancy. A newly appreciated syndrome. 860 77

Humoral hypercalcemia of malignancy (HHM) is caused by the secretion of parathyroid hormone-related protein (PTHrP) by tumor cells, and tumors of squamous histology are the ones most commonly complicated by HHM. To determine why some squamous tumors cause HHM and others do not, we quantitated the levels of PTHrP mRNA expression and PTHrP secretion in a series of eight squamous tumor lines. As anticipated, we found that the level of PTHrP mRNA expression in individual lines correlated with their PTHrP secretion rates. However, PTHrP mRNA levels varied widely in individual lines, and only those tumor lines with the highest levels of PTHrP gene expression were able to cause hypercalcemia in athymic mice. We found that a specific segment of the PTHrP promoter could reproduce the relative pattern of PTHrP gene expression when cloned in front of a chloramphenicol acetyltransferase reporter gene and transiently transfected into these squamous lines. Deletional analysis confirmed that specific sequences within the PTHrP gene promoter appeared to be involved in the transactivation of the gene in tumor lines expressing high levels of PTHrP mRNA. These data suggest that the ability of a given squamous tumor to cause HHM is ultimately a function of its level of PTHrP gene expression, which in turn appears to be a function of the ability of specific transcription factors to transactivate PTHrP gene expression.
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PMID:Transactivation of the PTHrP gene in squamous carcinomas predicts the occurrence of hypercalcemia in athymic mice. 864 Jul 59

Pamidronate (APD) is a drug widely used for the treatment of hypercalcemia of malignancy. Renal impairment has been associated with the use of other bisphosphonates in humans, and nephrotoxicity has been described after APD administration in animals. We retrospectively evaluated the safety and efficacy of APD administration in 31 patients with underlying renal insufficiency who received 33 courses of APD in doses of 60-90 mg. Hypercalcemia resolved or improved in 91% of the patients and only 1 case had severe hypocalcemia. A transient deterioration in renal function was observed in 8 courses but this was unrelated to APD administration. No systemic ill effects were observed. APD appears to be a safe drug in patients with underlying renal failure.
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PMID:Safety of pamidronate in patients with renal failure and hypercalcemia. 870 58

Measurement of parathyroid hormone-related peptide (PTHrP) associated with that of parathyroid hormone, allows to establish, in most cases, diagnosis of hypercalcemia of malignancy and more exactly of patients with Malignancy Humoral Hypercalcemia (MHH). Because of the variety of molecular forms of PTHrP, linked to its catabolism, its immunoassay remains difficult. After a study evaluating the methodological reliability, we measured the contribution of PTHrP to the hypercalcemia by 2 assays: a N-terminal RIA and a 1-72 IRMA in samples from 47 control subjects, 10 patients with chronic renal failure (IRC), 13 patients with primary hyperparathyroidism (HPT), and 48 patients with solid tumors classified by their level of calcemia: 48 normocalcemia and 23 hypercalcemia. We noted a strong correlation (r = 0.92) between the two assays. They do not show increases in renal insufficiency; they have a good diagnostic discrimination between HPT, normal subjects and patients with MHH. Elevated levels of PTHrP are similar in both assays. However, IRMA appears to be more sensitive and more practical than RIA. Moreover, it shows the best correlation between serum calcium and phosphorus in patients with MHH.
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PMID:[Performances of two kits for parathyroid hormone-related peptide (PTHrP) assay in the additional study of malignant hypercalcemias]. 874 2

Parathyroid hormone-related peptide was originally identified as a tumor-produced factor that mediated malignancy-associated hypercalcemia by binding to the common parathyroid hormone/parathyroid hormone-related peptide receptor to stimulate osteoclastic bone resorption and renal tubular resorption of calcium. Its role as a humoral factor in hypercalcemia of malignancy is well established, and recent work has demonstrated its importance as a tumor-produced factor in the pathogenesis of bone metastasis. Besides these cancer-related functions, work in the past decade has clearly established that parathyroid hormone-related peptide has many important functions in normal physiology related to growth and development, reproductive function and smooth muscle relaxation. Many other physiological functions are also being attributed to this versatile peptide. An understanding of these functions in malignancy and normal physiology should lead to innovative therapy for malignancy as well as other disorders not previously related to calcium homeostasis.
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PMID:Physiological and pathological roles of parathyroid hormone-related peptide. 882 27

The drug therapies for hypercalcemia of malignancy have been known to be associated with either limited efficacy or cumulative toxicity in patients with advanced renal failure. To establish the guidelines for the use of dialysis and to determine its optimal prescription for hypercalcemia, calcium-free hemodialysis was performed in 6 hypercalcemic patients with renal failure not responding enough to forced saline diuresis. Calcium-free dialysate contained sodium 135, potassium 2.5, chloride 108, magnesium 0.75, bicarbonate 30 mmol/l. Mean hemodialysis time was 160 +/- 27 min and mean Kt/V urea was 0.75 +/- 0.2. Plasma calcium concentrations fell from a mean value of 2.92 +/- 0.21 mmol/l (range 2.55-3.25) to 2.58 +/- 0.16 mmol/l at 1 h of hemodialysis and to 2.16 +/- 0.33 mmol/l (range 1.63-2.53) following 2-3 h of hemodialysis. The ionized calcium (n = 4) decreased from 1.44 +/- 0.14 mmol/l to 0.99 +/- 0.2 mmol/l. No patient showed any hypocalcemic symptoms and signs during hemodialysis. The rate of decrease in plasma calcium did not appear to produce adverse effects in any of the patients. There was a significant positive correlation between the decrease in plasma calcium concentration and the Kt/V urea (y = 1.4x - 0.29, r = 0.92, p < 0.01). We conclude that calcium-free hemodialysis is indicated when the presence of severe renal failure prevents the administration of large volumes of intravenous fluids to hypercalcemic patients. The amount of dialysis (Kt/V urea) can be used to predict the decrease in plasma calcium concentration during calcium-free hemodialysis.
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PMID:Calcium-free hemodialysis for the management of hypercalcemia. 885 91

Malignant hypercalcemia is seldom the cause of an acute pancreatitis; this complication is more frequent when hypercalcemia is due to hyperparathyroidism. We present a case of acute pancreatitis triggered by a malignant hypercalcemia as the first sign of the neoplastic process. Solid tumors with bone extension can produce hypercalcemia and may be the origin of hypercalcemic pancreatitis.
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PMID:[Pancreatitis caused by hypercalcemia of malignant origin]. 896 82

Humoral hypercalcemia of malignancy results from the effects of tumor-produced factors on bone, kidney, and intestine that disrupt normal calcium homeostasis. Although parathyroid hormone-related protein (PTHrP) is a major mediator of the syndrome, tumors also produce other hypercalcemic factors, such as tumor necrosis factor (TNF), which may modulate the effects of PTHrP. It has been postulated that TNF may counteract the stimulatory effects of PTHrP on bone formation. To examine the effects of TNF on PTHrP-induced changes in calcium and bone metabolism, a murine tumor model of hypercalcemia was used. Nude mice were inoculated with Chinese hamster ovarian (CHO) cells expressing human TNF (CHO/TNF) or nontransfected CHO cells (CHO/-) and further treated with injections of human PTHrP(1-34) or vehicle. The effects of TNF, PTHrP, and the combination of the two factors on blood ionized calcium, osteoclast recruitment, and bone histomorphometry were evaluated. Mice bearing CHO/TNF tumors that were injected with PTHrP had significantly higher calcium concentrations, increased committed osteoclast progenitors, and mature osteoclasts as well as enhanced bone resorption compared with mice bearing CHO/TNF tumors injected with vehicle or those bearing CHO/- tumors injected with PTHrP or vehicle. A 2-fold increase in new woven bone formed in the calvaria at sites of previous bone resorption was observed in CHO/TNF mice treated with PTHrP. Bone formation rates in the vertebrae were similar in both CHO/- and CHO/TNF mice treated with PTHrP. These data demonstrate that the hypercalcemic effects of PTHrP are enhanced by TNF and that this effect is due to the increased production of committed osteoclast precursors with a subsequent increase in osteoclastic bone resorption. Furthermore, PTHrP caused a coupled increase in osteoclastic bone resorption and new bone formation that was not inhibited by TNF. These findings highlight the complex interactions that may occur between tumor-produced factors on bone that result in malignancy-associated hypercalcemia and suggest that TNF may not be responsible for the decreased bone formation seen in some patients with this condition.
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PMID:Tumor necrosis factor enhances parathyroid hormone-related protein-induced hypercalcemia and bone resorption without inhibiting bone formation in vivo. 924 49


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