Essay about Hypercalcemia

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Overview
Hypercalcemia is the most common life-threatening metabolic disorder associated with neoplastic diseases, occurring in an estimated 10% to 20% of all adults with cancer. It also occurs in children with cancer, but with much less frequency (approximately 0.5%–1%).[1-3] Solid tumors (such as lung or breast cancer tumors) as well as certain hematologic malignancies (particularly multiple myeloma) are most frequently associated with hypercalcemia.[4] Although early diagnosis followed by hydration and treatment with agents that decrease serum calcium concentrations (hypocalcemic drugs) can produce symptomatic improvements within a few days, diagnosis may be complicated because symptoms may be insidious at onset and can be confused
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Minute-to-minute regulation of serum-ionized calcium is regulated by PTH. PTH secretion is stimulated when ambient serum-ionized calcium is decreased. PTH acts on peripheral target cell receptors, increasing the efficiency of renal tubular calcium reabsorption. In addition, PTH enhances calcium resorption from mineralized bone and stimulates conversion of vitamin D to its active form, calcitriol, which subsequently increases intestinal absorption of calcium and phosphorus. Pharmacologic doses of calcitonin act as an antagonist to PTH, lowering serum calcium and phosphorus and inhibiting bone reabsorption.
Renal function
Normal, healthy kidneys are capable of filtering large amounts of calcium, which is subsequently reclaimed by tubular reabsorption. The kidneys are capable of increasing calcium excretion nearly fivefold to maintain homeostatic serum calcium concentrations. Hypercalcemia may occur, however, when the concentration of calcium present in the extracellular fluid overwhelms the kidneys’ compensatory mechanisms.
Although calcium reabsorption is linked to sodium and fluid reabsorption in the proximal renal tubules, fine regulation occurs in the distal renal tubules primarily under the influence of PTH. Tumors that are capable of producing a substance similar to normal PTH such as PTH-related peptide (refer to the

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