Hypercalcemia

Hypercalcemia is a metabolic abnormality with widespread effects. Mild or chronic persistent hypercalcemia may be asymptomatic, whereas acute onset hypercalcemia may present with musculoskeletal, gastrointestinal, and psychiatric changes. If a patient is taking calcium supplements and has a test result bordering on hypercalcemia, testing should be repeated after cessation of supplementation. Accurate calcium testing includes correction with a concurrent albumin concentration. Testing for ionized calcium can remove variability due to albumin or confirm a possible abnormal value. Confirmed high serum calcium is frequently associated with hyperparathyroidism or undetected cancer. Laboratory testing includes parathyroid hormone (PTH) testing, testing to identify organ involvement, and, in the event of low PTH, testing for cancer.

Diagnosis

Indications for Testing

  • Fatigue, muscle weakness, recurrent nephrolithiasis, bone pain, constipation, changes in mental status
  • Elevated calcium on laboratory testing

Laboratory Testing

  • Initial testing: comprehensive metabolic panel (CMP)
    • Abnormalities in other lab results may provide clues to underlying pathology
    • Chronic kidney disease with metabolic bone disease results in abnormalities of calcium, phosphorus, PTH, and bone turnover
  • Calcium
    • Calculate corrected calcium
      • Corrected calcium = serum calcium + [0.8 x (normal albumin - serum albumin)]
      • Normal albumin is usually 4-4.5 g/dL, depending on testing lab
    • Consider ionized calcium if albumin is low
    • Total serum calcium
      • In asymptomatic patient with concentration >10.3 but <11.0 mg/dL, repeat with albumin measurement or ionized calcium
      • In symptomatic patient and/or patient with concentration >11.0 mg/dL: order PTH
  • PTH (intact)
    • Elevated or normal: indicates primary hyperparathyroidism; order urine calcium, 24-hour collection
      • High urine calcium (‚Č•100 pg/mL): primary hyperparathyroidism
      • Low urine calcium (<100 pg/mL): familial benign hypercalcemia
    • Low: order PTH-related peptide (PTHrP)
      • High PTHrP: consider cancer
      • Low or normal PTHrP: order vitamin D, 1,25-dihydroxy [1,25-(OH)2-D]
        • High 1,25-(OH)2-D: consider lymphoma or granulomatous disease
        • Low or normal 1,25-(OH)2-D: consider vitamin D excess, cancer, milk-alkali syndrome, or hyperthyroidism
  • Other testing
    • Thyroid-stimulating hormone (TSH): rarely, hyperthyroidism can cause hypercalcemia

ARUP Laboratory Tests

Related Tests

Panel includes albumin, calcium, carbon dioxide, creatinine, chloride, glucose, phosphorous, potassium, sodium, blood urea nitrogen (BUN), and a calculated anion gap value

References

Additional Resources

Medical Experts

Contributor

Pearson

Lauren N. Pearson, DO, MPH
Associate Professor of Pathology (Clinical), University of Utah
Laboratory Director for ARUP at University of Utah Health and Huntsman Cancer Institute
Laboratory Director, South Jordan and Sugarhouse Health Center Clinical Laboratories
Contributor