A 55-year-old woman undergoes total thyroidectomy for multinodular goiter. On postoperative day 2, she has a serum calcium of 7.8 mg/dL (albumin-corrected) and phosphate of 5.2 mg/dL. She is asymptomatic. PTH level is 8 pg/mL (normal 15-65 pg/mL). What is the most appropriate management?

• A Oral calcium carbonate alone
• B Observation with repeat calcium measurement in 24 hours
• C Intravenous calcium gluconate bolus followed by infusion
• D Oral calcium carbonate plus calcitriol (1,25-dihydroxyvitamin D) ✓

Explanation

This patient has biochemical hypoparathyroidism (low PTH, hypocalcemia, hyperphosphatemia) post-thyroidectomy. Even though asymptomatic, she requires both oral calcium and calcitriol because the low PTH impairs renal conversion of 25-hydroxyvitamin B to active 1,25-dihydroxyvitamin B. Calcium alone is insufficient without calcitriol in hypoparathyroidism. IV calcium is reserved for symptomatic hypocalcemia or severe hypocalcemia (<7.0 mg/dL). Observation is inappropriate as calcium is already low and PTH is suppressed, indicating likely persistent hypoparathyroidism.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.