What specialty do you refer a patient with hypercalcemia to?

Referral for High Ionized Calcium (Hypercalcemia)

Patients with hypercalcemia should be referred to an endocrinologist, particularly when hyperparathyroidism is suspected, as they are the specialists with expertise in managing disorders of calcium metabolism. 1, 2

Diagnostic Approach to Hypercalcemia

Before referral, initial workup should include:

• Corrected calcium calculation (if ionized calcium is already elevated, this confirms hypercalcemia)
• Intact parathyroid hormone (iPTH) levels
• Phosphorus, magnesium, renal function tests
• 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels
• Urinary calcium/creatinine ratio 2

Referral Decision Algorithm

1. Refer to Endocrinology when:

• Primary hyperparathyroidism is suspected (elevated or inappropriately normal PTH with hypercalcemia)
• Familial hypocalciuric hypercalcemia is suspected
• Multiple endocrine neoplasia syndromes are suspected
• Vitamin D-related disorders causing hypercalcemia 1, 2

2. Refer to Nephrology when:

• eGFR < 30 mL/min/1.73 m² with hypercalcemia
• Hypercalcemia with significant kidney injury
• Complex electrolyte disturbances accompany hypercalcemia 1

3. Refer to Oncology when:

• Malignancy-associated hypercalcemia is suspected
• Known cancer patient develops hypercalcemia 2, 3

Special Considerations

Severity-Based Management

• Mild hypercalcemia (total calcium <12 mg/dL): Generally can be managed outpatient with appropriate specialty referral 3
• Severe hypercalcemia (total calcium ≥14 mg/dL): May require emergency management before or concurrent with specialty referral 2, 3

Multiple Endocrine Neoplasia (MEN) Syndromes

For patients with suspected MEN syndromes and hypercalcemia:

• Refer to an endocrinologist with experience in managing parathyroid disease 1
• The endocrinologist will coordinate with surgeons experienced in parathyroid surgery when indicated 1

Hyperparathyroid-Jaw Tumor Syndrome

For patients with suspected CDC73 mutations (HPT-JT syndrome):

• Refer to an endocrinologist for management of hyperparathyroidism
• The endocrinologist will coordinate multidisciplinary care with high-volume parathyroid surgeons 1

Common Pitfalls to Avoid

• Delaying referral for severe symptomatic hypercalcemia (should be treated as a medical emergency)
• Failing to correct calcium for albumin when total calcium is measured
• Treating laboratory values without addressing the underlying cause
• Referring to the wrong specialty based on incomplete workup 2

Follow-up After Referral

After initial specialty referral, patients may require:

• Surgical consultation with a high-volume parathyroid surgeon if parathyroidectomy is indicated
• Regular monitoring of calcium, phosphate, and renal function
• Bone density testing to assess for bone loss 2, 3

The endocrinologist remains the primary specialist for ongoing management of hypercalcemia, particularly when related to endocrine disorders, while coordinating care with other specialists as needed.