A 52-year-old woman from Delhi presents with muscle cramps, paresthesias in fingers and lips, and a positive Chvostek's sign. Serum calcium is 7.2 mg/dL (normal 8.5–10.5), phosphate is 5.8 mg/dL (normal 2.5–4.5), and PTH is 12 pg/mL (normal 15–65). She has a 10-year history of thyroid surgery for Graves' disease. What is the most appropriate immediate next step?

Explanation

## Clinical Context This patient has **symptomatic hypocalcemia** (serum Ca 7.2 mg/dL with neuromuscular signs: muscle cramps, paresthesias, positive Chvostek's sign) secondary to **hypoparathyroidism** (low PTH, high phosphate post-thyroidectomy—likely iatrogenic parathyroid injury). ## Why IV Calcium Gluconate Is the Correct Answer **Key Point:** Symptomatic hypocalcemia with neuromuscular manifestations (tetany, seizure risk) is a **medical emergency** requiring immediate IV calcium replacement to prevent life-threatening complications (laryngeal stridor, cardiac arrhythmias, seizures). **High-Yield:** The presence of **positive Chvostek's sign** (facial muscle twitch on tapping the facial nerve) indicates severe hypocalcemia and neuromuscular irritability—this is a red flag for imminent tetany or seizure. ### Mechanism of IV Calcium Gluconate - Rapidly raises serum ionized calcium (therapeutic effect within minutes) - Stabilizes neuronal and cardiac membrane excitability - Prevents progression to tetany, laryngeal stridor, or seizures - Dose: 10% solution, 10–20 mL IV over 2–5 minutes (can repeat if symptoms persist) ## Subsequent Management (After Acute Stabilization) | Step | Rationale | |------|----------| | Check serum Mg, vitamin D, albumin | Hypomagnesemia and vitamin D deficiency impair PTH secretion and calcium reabsorption; correct these to optimize response | | Start oral calcium + calcitriol (active vitamin D) | Long-term management of hypoparathyroidism; oral calcium alone is insufficient for acute symptoms | | Imaging and surgery | Relevant only if parathyroid tissue is viable; in post-thyroidectomy hypoparathyroidism, surgery is rarely curative | **Clinical Pearl:** Do NOT delay IV calcium while awaiting magnesium or vitamin D results—symptomatic hypocalcemia takes priority. Magnesium and vitamin D are checked *after* acute stabilization. **Warning:** Oral calcium carbonate alone is too slow for symptomatic hypocalcemia; it takes hours to raise serum calcium and will not prevent seizures or laryngeal stridor.