Recognize
- Use ionized Ca or correct: Ca + 0.8 × (4 − albumin)
- Symptoms: perioral numbness, paresthesias, tetany, carpopedal spasm, seizure, laryngospasm
- Signs: Chvostek (facial twitch), Trousseau (BP cuff carpal spasm)
- EKG: prolonged QT, torsades
- Causes: hypoparathyroidism (post-thyroidectomy), vitamin D deficiency, CKD, pancreatitis, rhabdo, TLS, sepsis, massive transfusion (citrate), hypomagnesemia
Symptomatic / severe IV
- Calcium gluconate 1–2 g IV over 10 min (peripheral OK) — repeat PRN
- Calcium chloride 1 g IV via central line (3× elemental Ca, vesicant)
- Follow with infusion: Ca gluc 1 g/h until symptoms resolve / iCa > 1.0
- Recheck iCa q1–2h during infusion
Asymptomatic / mild
- Calcium carbonate / citrate 1–2 g elemental PO TID
- Vitamin D (calcitriol 0.25–0.5 mcg PO daily) if deficient or hypoparathyroid
Co-repletion
- Replace Mg first if low — refractory until corrected
- Caution Ca in digoxin toxicity — slow infusion, monitor closely (historically "stone heart" — now considered safe but cautious)
Disposition
- Admit: symptomatic, QT prolonged, post-thyroidectomy, severe (iCa < 0.8)