What is the diagnosis and management for an adult patient with elevated PTH, hypercalcemia, and a vitamin D level of 31.6?

Primary Hyperparathyroidism with Hypercalcemia

This patient has primary hyperparathyroidism (PHPT) based on the combination of elevated PTH (57 pg/mL) with hypercalcemia (ionized calcium 6.1 mg/dL, total calcium 10.3 mg/dL), and requires urgent evaluation for parathyroidectomy given the severity of biochemical abnormalities. 1

Diagnostic Confirmation

The biochemical profile is diagnostic of primary hyperparathyroidism without need for imaging:

• An elevated or normal PTH in the setting of hypercalcemia is biochemically diagnostic of primary hyperparathyroidism, regardless of imaging results 1
• The ionized calcium of 6.1 mg/dL (reference range typically 4.6-5.3 mg/dL) represents significant hypercalcemia 2
• PTH should be suppressed (<20 pg/mL) in the presence of hypercalcemia if the cause were PTH-independent (such as malignancy), but this patient's PTH is elevated at 57 pg/mL 2, 3

Vitamin D Status Assessment

The vitamin D level of 31.6 ng/mL is technically sufficient but warrants consideration:

• Vitamin D deficiency is more prevalent in patients with primary hyperparathyroidism than in matched populations and may worsen disease severity 4
• Co-existing vitamin D deficiency can cause serum calcium to fall into the normal range, potentially masking the diagnosis 4
• This patient's vitamin D level of 31.6 ng/mL is above the deficiency threshold (<30 ng/mL), so the hypercalcemia is not being masked 5

Immediate Management Priority

Parathyroidectomy should be pursued as definitive treatment, as this patient meets surgical criteria based on the degree of hypercalcemia 1:

• The American Association of Endocrine Surgeons recommends parathyroidectomy for severe hyperparathyroidism with hypercalcemia that precludes medical therapy 1
• Referral to an experienced parathyroid surgeon should occur immediately 1
• Imaging (sestamibi scan, ultrasound, or 4D-CT) is for surgical planning only, not for diagnosis 1

Medical Stabilization While Awaiting Surgery

If surgery must be delayed, medical management includes:

• Avoid calcium supplements and vitamin D supplementation, as these worsen hypercalcemia 1
• Ensure adequate hydration to promote calciuresis 1
• Monitor serum calcium every 1-2 weeks until surgery 1
• Review all medications for thiazide diuretics (which worsen hypercalcemia) and lithium (which can cause hypercalcemia with elevated PTH) 1

Critical Pitfall to Avoid

Do not attempt to correct the "low" vitamin D level with supplementation in the presence of hypercalcemia, as this will worsen the hypercalcemia 1. While preliminary data suggest vitamin D repletion may be safe in some mild PHPT cases, this should only be considered after surgical evaluation and with close calcium monitoring 4.

Postoperative Considerations

After parathyroidectomy, this patient will require:

• Monitoring of ionized calcium every 4-6 hours for the first 48-72 hours, then twice daily until stable, as hungry bone syndrome is common 1
• Supplemental calcium carbonate 1-2 g three times daily and calcitriol up to 2 μg/day to manage expected postoperative hypocalcemia 1
• Vitamin D deficiency can then be safely corrected postoperatively 4

Alternative Management Only If Surgery Contraindicated

If parathyroidectomy is absolutely contraindicated due to surgical risk, cinacalcet may be considered:

• Cinacalcet is FDA-approved for hypercalcemia in primary hyperparathyroidism when parathyroidectomy is indicated but the patient cannot undergo surgery 6
• Starting dose is 30 mg twice daily, titrated every 2-4 weeks to normalize serum calcium 6
• Serum calcium must be monitored within 1 week after initiation or dose adjustment 6