Hypercalcemia is a common metabolic abnormality seen in both inpatient and outpatient settings. Depending on the serum calcium levels, hypercalcemia is categorized either as mild (just above normal but <12 mg/dL), moderate (between 12 and 14 mg/dL), or severe (>14 mg/dL). Approximately 40% to 45% of the serum calcium is attached to albumin, and serum calcium levels may fluctuate based on the serum albumin levels. Therefore, the ionized or free calcium levels should be measured when hypercalcemia is suspected for a more accurate assessment.
The corrected calcium could also be calculated using the below formula:
Serum calcium + 0.8 × (4 − patient’s albumin level), where 4.0 g/dL is the normal albumin level.
More than 90% of hypercalcemia cases are caused by primary hyperparathyroidism (PHPT) or malignancy-induced hypercalcemia, with malignancy being the most common cause of hypercalcemia in hospitalized patients.
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