A 42-year-old woman is evaluated in the hospital on postoperative day 2 following a total … — USMLE Step 2 CK

A $42$ -year-old woman is evaluated in the hospital on postoperative day $2$ following a total thyroidectomy for a large toxic multinodular goiter. Her current medications include levothyroxine. She reports new-onset tingling around her mouth and in the fingertips of both hands. She also mentions mild nausea and states she has not had a bowel movement since before the surgery. She has no difficulty breathing or voice changes. Vital signs are temperature $38.0^{\circ}\text{C}$ ( $100.4^{\circ}\text{F}$ ), blood pressure $122/78\text{ mmHg}$ , heart rate $84/\text{min}$ , and respiratory rate $14/\text{min}$ . Physical examination reveals twitching of the ipsilateral facial muscles when the area just anterior to the earlobe is tapped. The surgical incision is clean, dry, and intact without erythema or fluctuance. The lungs are clear to auscultation. The abdomen is soft and non-distended with hypoactive bowel sounds.

Laboratory results are as follows:

Laboratory Test	Result	Reference Range
Serum total calcium	$7.5\text{ mg/dL}$	$8.4 - 10.2\text{ mg/dL}$
Serum albumin	$4.0\text{ g/dL}$	$3.5 - 5.0\text{ g/dL}$
Serum phosphorus	$5.2\text{ mg/dL}$	$2.5 - 4.5\text{ mg/dL}$
Serum intact parathyroid hormone	$8\text{ pg/mL}$	$15 - 65\text{ pg/mL}$
Serum TSH	$0.1\text{ \mu U/mL}$	$0.4 - 4.0\text{ \mu U/mL}$
Serum free T4	$1.9\text{ ng/dL}$	$0.9 - 1.7\text{ ng/dL}$

Which of the following is the most appropriate next step in the management of this patient?

Oral administration of calcium carbonate and calcitriolAnswer
B
Decrease the daily dose of levothyroxine
C
Order a lower extremity venous duplex ultrasound
D
Administer intravenous vancomycin and piperacillin-tazobactam
E
Insert a nasogastric tube for gastric decompression

Answer

The most appropriate next step is the oral administration of calcium carbonate and calcitriol.

The correct answer is oral administration of calcium carbonate and calcitriol. This patient presents with perioral tingling and a positive Chvostek sign on postoperative day 2 following a total thyroidectomy. Her laboratory results confirm hypocalcemia, hyperphosphatemia, and an inappropriately low parathyroid hormone (PTH) level, establishing the diagnosis of primary hypoparathyroidism. This is a well-known complication of total thyroidectomy caused by inadvertent injury, devascularization, or removal of the parathyroid glands. Because her symptoms are mild (paresthesias and Chvostek sign without severe features like tetany, carpopedal spasm, seizures, or arrhythmias), the most appropriate management is oral calcium supplementation combined with calcitriol (1,25-dihydroxycholecalciferol). Calcitriol is necessary because the lack of PTH impairs the renal conversion of 25-hydroxyvitamin D to its active form. Intravenous calcium gluconate is reserved for severe, life-threatening symptoms or a serum calcium level strictly below

7.0\text{ mg/dL}

Step-by-Step Solution

Evaluate the patient's acute symptoms and physical examination findings.

Identified perioral tingling and a positive Chvostek sign (facial muscle twitching).

These are classic signs of neuromuscular irritability indicating clinical hypocalcemia.

Analyze the laboratory results in the context of recent surgery.

Confirmed hypocalcemia (

7.5\text{ mg/dL}

) and hyperphosphatemia with inappropriately low parathyroid hormone (

8\text{ pg/mL}

To diagnose postoperative primary hypoparathyroidism, a known complication of total thyroidectomy.

Determine the appropriate severity-based treatment for hypocalcemia.

Selected oral calcium carbonate and calcitriol.

The patient has mild to moderate symptoms without life-threatening features (e.g., tetany, arrhythmias), which warrants oral replacement rather than intravenous calcium.

Assess other clinical findings to ensure no other emergent interventions are required.

Identified low-grade fever and mild ileus as normal postoperative day 2 findings, and recognized suppressed TSH as an expected residual effect of toxic multinodular goiter.

To rule out infection, deep vein thrombosis, or bowel obstruction, and confirm that conservative management of these secondary findings is appropriate.

Key Concept

Mild to moderate symptomatic postoperative hypocalcemia following thyroidectomy is managed with oral calcium and calcitriol, prioritizing acute stabilization over expected postoperative lab abnormalities or normal physiologic surgical responses.

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