Hospital Admission Threshold for Hypercalcemia
Patients with hypercalcemia should be admitted to the hospital when corrected serum calcium exceeds 12 mg/dL (3.0 mmol/L), particularly if symptomatic or if the elevation developed rapidly.
Severity-Based Admission Criteria
Severe Hypercalcemia (Requires Admission)
- Corrected serum calcium >12 mg/dL (3.0 mmol/L) is the threshold recommended by the American College of Physicians for treating hypercalcemia of malignancy and warrants hospital admission 1
- Total calcium ≥14 mg/dL (≥3.5 mmol/L) or ionized calcium ≥10 mg/dL (≥2.5 mmol/L) defines severe hypercalcemia that can cause nausea, vomiting, dehydration, confusion, somnolence, and coma, requiring immediate hospitalization 2
- Patients presenting to the emergency department with severe hypercalcemia have a mortality rate of 23.1%, making prompt admission critical 3
Moderate Hypercalcemia (Selective Admission)
- Total calcium 12-14 mg/dL with symptoms (fatigue, constipation, nausea, confusion) should prompt admission 2
- Rapid onset over days to weeks, even with calcium <14 mg/dL, increases risk and favors admission 2
- ICU admission should be considered for severe hypercalcemia (>12 mg/dL) with organ dysfunction, as 82.4% develop acute kidney injury and mortality reaches 21.3% 4
Mild Hypercalcemia (Outpatient Management)
- Total calcium <12 mg/dL (<3.0 mmol/L) without symptoms can typically be managed outpatient 2
- Asymptomatic primary hyperparathyroidism with calcium <1 mg/dL above upper normal limit in patients >50 years may be observed 2
Clinical Features Requiring Admission
Neurological Manifestations
- Confusion, somnolence, or altered mental status occurs in 38.9% of severe hypercalcemia cases and mandates admission 4
- These symptoms indicate severe hypercalcemia requiring immediate intervention 2
Cardiovascular and Renal Complications
- Cardiovascular manifestations occur in 55.7% of patients with severe hypercalcemia 4
- Acute kidney injury develops in 82.4% of patients with calcium >12 mg/dL, with 19% requiring renal replacement therapy 4
- Volume contraction and calcium-induced nephrocalcinosis play critical roles in worsening hypercalcemia 5
Gastrointestinal Symptoms
- Nausea, vomiting, and dehydration occur in 38.1% of severe cases and contribute to volume depletion 4
Etiology-Specific Considerations
Malignancy-Related Hypercalcemia
- Treatment threshold is corrected calcium >12 mg/dL (3.0 mmol/L) per International Myeloma Society guidelines 1
- Hypercalcemia of malignancy typically presents with rapid onset, higher calcium levels, and more severe symptoms than primary hyperparathyroidism 6
- Underlying solid tumors are independently associated with hospital mortality (OR 13.83) 4
Primary Hyperparathyroidism
- Usually presents with calcium <12 mg/dL and chronic duration (>6 months) 6
- Admission rarely needed unless symptomatic or complicated by kidney stones or severe bone disease 6
Common Pitfalls to Avoid
- Do not delay admission for patients with calcium >12 mg/dL even if mildly symptomatic, as rapid deterioration can occur 3
- Check ionized calcium when total calcium interpretation is unclear due to albumin abnormalities 2
- Measure PTH immediately on admission to distinguish PTH-dependent from PTH-independent causes and guide treatment 2, 6
- Assess for acute kidney injury as it occurs in >80% of severe cases and may require urgent dialysis 4
- Avoid sedatives and narcotics in borderline cases as they reduce activity and oral intake, potentially worsening hypercalcemia 5
Risk Stratification for Admission Decision
Admit if ANY of the following:
- Corrected calcium >12 mg/dL (3.0 mmol/L) 1
- Any neurological symptoms (confusion, lethargy) 4
- Rapid onset (days to weeks) 2
- Underlying malignancy with calcium >11.5 mg/dL 7
- Evidence of acute kidney injury 4
- Inability to maintain adequate oral hydration 5
Consider outpatient management only if: