Calcium Repletion for Mild‑to‑Moderate Hypocalcemia (Ionized Ca ≈ 0.86 mmol/L)

Severity Assessment & Indications

In patients with ionized calcium ≈ 0.86 mmol/L who lack life‑threatening symptoms, initiate a single 1‑g IV bolus of calcium gluconate (≈ 90 mg elemental calcium) administered over 10 minutes; reassess thereafter and consider a continuous infusion rather than a second immediate bolus. 1, 2, 3
Immediate IV calcium is required when severe manifestations (seizures, laryngospasm, tetany, bronchospasm) or QTc prolongation (> 0.45 s in men, > 0.47 s in women) are present, irrespective of the absolute calcium value. 1, 2, 3, 4
An albumin‑corrected calcium < 1.9 mmol/L (≈ 7.5 mg/dL) generally justifies IV calcium therapy even in the absence of severe symptoms. 1, 2, 3

The standard initial bolus is 1 g calcium gluconate (≈ 90 mg elemental calcium) infused over 10–20 minutes with continuous cardiac monitoring. 1, 2, 3, 4
Guideline recommendations allow a bolus range of 90–180 mg elemental calcium (1–2 g calcium gluconate); beginning with the lower end facilitates safer titration. 1, 2, 3

Rapid infusion may precipitate cardiac arrest; therefore cardiac monitoring is mandatory during administration. 1, 2, 3
Use a secure, large‑bore intravenous line to reduce the risk of extravasation. 1, 2, 3
Calcium gluconate is preferred over calcium chloride because it carries a lower risk of tissue necrosis if extravasation occurs. 1, 2, 3, 4

If ionized calcium remains low or symptoms persist, start a continuous infusion: 10 g calcium gluconate (≈ 900 mg elemental calcium) diluted in 1 L D5W or normal saline, infused at 100 mL/h and titrated according to ionized calcium measured every 6 hours. 1, 2, 3, 4
Begin concurrent oral calcium supplementation together with calcitriol 0.25–0.5 µg twice daily to support sustained calcium repletion. 1, 2, 3, 4

Aim for a low‑normal ionized calcium level (just below the standard reference range) to avoid hypercalciuria and related complications. 1, 2, 3, 4
In patients with baseline QTc prolongation, monitor for QTc normalization as calcium is corrected. 1, 6, 7
Re‑measure ionized calcium 4–7 days after any dosage adjustment in unstable patients to ensure stability of the correction. 8, 3