Hypercalcemia of Malignancy, Humoral

• • Hypercalcemia due to hormonal product of nonparathyroid cancer

  • Most common cause of hypercalcemia in hospitalized patients

Laboratory Findings

• • Low intact parathyroid hormone level

  • Elevated parathyroid hormone-related protein level

  • Anemia

  • Elevated serum calcium sometimes (to > 14 mg/dL)

  • Increased alkaline phosphatase activity

• • Most common tumors causing ectopic hyperparathyroidism are the following:

  • -Squamous cell carcinoma of the lung

    -Renal cell carcinoma

    -Bladder cancer

  • Less common offending tumors are the following:

  • -Hepatoma

    -Tumors of the ovary, stomach, pancreas, parotid gland, or colon

Rule Out

• • Primary hyperparathyroidism

  • Familial Hypocalciuric Hypercalcemia (FHH)

• • History and physical exam

  • Laboratory evaluation

  • Search for primary malignancy

  • Elevated or non-suppressed PTH with elevated calcium implies primary hyperparathyroidism

  • Suppressed PTH implies normal parathyroid function; most common diagnosis is malignancy

  • Mild elevation of PTH and calcium can by FHH

When to Admit

• • Hypercalcemic crisis

• • Treatment is directed at normalizing serum calcium level

  • Treatment of primary tumor treats malignancy-associated hypercalcemia

References