Should vitamin D deficiency be corrected before parathyroidectomy?

BACKGROUND: Vitamin D deficiency is common in patients with hyperparathyroidism, but the importance of replacement before surgery is controversial. We aimed to evaluate the impact of vitamin D deficiency on the extent of resection and risk of postoperative hypocalcemia for patients undergoing parathyroidectomy for primary hyperparathyroidism. METHODS: We identified patients with primary hyperparathyroidism undergoing parathyroid surgery between 2000 and 2015 using a prospectively maintained database. Patients with normal (≥30 ng/mL) vitamin D were compared to those with levels less than 30 ng/mL. RESULTS: There were 1015 (54%) patients with normal vitamin D and 872 (46%) patients with vitamin D deficiency undergoing parathyroidectomy for primary hyperparathyroidism. Vitamin D deficiency was associated with higher preoperative parathyroid hormone (median 90 versus 77 pg/mL, P < 0.001) and calcium (median 10.5 versus 10.4 mg/dL, P < 0.001) compared with normal vitamin D. To achieve similar cure rates, patients with vitamin D deficiency were less likely to require removal of more than one gland (20% versus 30%, P < 0.001) than patients with normal vitamin D. Patients with vitamin D deficiency had similar rates of persistent (1.5% versus 2.0%, P = 0.43) and recurrent (1.7% versus 2.6%, P = 0.21) hyperparathyroidism. Postoperatively, both groups had equivalent rates of transient (2.3% versus 2.3%, P = 0.97) and permanent (0.2% versus 0.4%, P = 0.52) hypocalcemia. CONCLUSIONS: Restoring vitamin D in deficient patients should not delay the appropriate surgical treatment of primary hyperparathyroidism. Deficient patients are more likely to be cured with the excision of a single adenoma and no more likely to suffer persistence, recurrence, or hypocalcemia than patients with normal vitamin D.