Hypocalcemia
Serum calcium less than 9.0 mg/dL
Definition
Hypocalcemia is a serum total calcium less than 9.0 mg/dL (or ionized calcium less than 4.6 mg/dL). It increases neuromuscular excitability and cardiovascular risk.
Causes
- Hypoparathyroidism (post-thyroidectomy)
- Vitamin D deficiency
- Chronic kidney disease
- Pancreatitis (calcium binds fat necrosis)
- Massive blood transfusion (citrate binds calcium)
- Magnesium deficiency
Classic Signs
- Chvostek's sign: Facial twitch on cheek tap.
- Trousseau's sign: Carpopedal spasm with BP cuff inflation.
- Tetany, paresthesia (circumoral, fingers), laryngospasm, seizures.
- Prolonged QT interval, arrhythmias.
Nursing Interventions
Monitor ECG, seizure precautions, calcium gluconate IV for severe symptoms (slow push), oral calcium + vitamin D supplementation. Correct low magnesium first if present.
NCLEX Relevance
Post-thyroidectomy: monitor for hypocalcemia.