Hypocalcemia & Hypercalcemia
at the bedside
- vitals; symptomatic? acute vs chronic?
- ECG
- hypocalcemia → QT prolongation
- hypercalcemia → QT shortening
escalate now if
- hypocalcemia: tetany, laryngospasm, seizures, arrhythmia
- hypercalcemia: severe dehydration, altered mental status, arrhythmia, weakness
focused check
hypocalcemia
causes
- post thyroid / parathyroid surgery
- CKD · vitamin D deficiency
- hypoparathyroidism · hypomagnesemia
- pancreatitis · sepsis
symptoms & signs
- perioral numbness, muscle cramps, tetany
- Chvostek sign · Trousseau sign · hyperreflexia
hypercalcemia
causes
- primary hyperparathyroidism
- malignancy (PTHrP, bony metastases, myeloma)
- excess vitamin D · granulomatous disease
- immobilization · thiazides
signs
- dehydration · renal: polyuria, stones · GI: nausea, vomiting · neuro: confusion, reduced reflexes
send now
hypocalcemia
- PTH · vitamin D · magnesium
ECGQT prolongation
corrected calcium
- corrected Ca (mmol/L) = measured Ca + 0.02 × (40 − albumin g/L)
calculator corrected calcium · MDCalc ↗︎
hypercalcemia
PTH-guided workup
- PTH high/inappropriately normal → primary or tertiary hyperparathyroidism
- PTH suppressed → PTHrP, vitamin D, myeloma screen, malignancy
- also: CBC, ALP, VBG
ECGQT shortening
treat
hypocalcemia: replace by severity
| 1.9–2.2mild · mmol/L | usually asymptomatic ± QT prolongation calcium carbonate 1–2 g/day PO divided |
| < 1.9severe / symptomatic | tetany, seizures, QT / arrhythmia calcium gluconate 1–2 g IV over 10–20 min · repeat PRN · cardiac monitoring |
correct magnesium first
- low Mg causes refractory hypocalcemia (see Mg page)
- escalate to IV if symptomatic or oral-intolerant
hypercalcemia: by severity
| 2.6–3.0mild · mmol/L | IV fluids 1–2 L bolus NS then maintenance |
| 3.0–3.5moderate · mmol/L | IV fluids · recheck · watch for deterioration |
| > 3.5severe · mmol/L | fluids + escalate early · senior review |
- calcitonin 4 IU/kg SC/IM q12h → rapid onset, tachyphylaxis by 48–72h (bridge only)
- bisphosphonate: zoledronic acid 4 mg IV → definitive, onset 2–4 days
- denosumab 120 mg SC → if bisphosphonates contraindicated / ineffective (e.g. renal impairment)
- 2024 FDA boxed warning: severe hypocalcemia in advanced CKD, especially dialysis / CKD-MBD; monitor calcium closely
- diuretics → only if fluid overload
available calcium
| product | elemental calcium | usual adult dose | bedside note |
|---|---|---|---|
| IV calcium gluconate 10% | 10 mL = 2.2 mmol Ca | 10–20 mL (1–2 g) IV over 10 min, undiluted or in 50–100 mL glucose 5% / NaCl 0.9%; repeat by calcium and ECG | rate ≤ 0.45 mmol/min; good peripheral access, extravasation causes necrosis; usual first choice |
| IV calcium chloride 10% | 10 mL = 6.8 mmol Ca (≈3× gluconate per mL) | 5–10 mL (0.5–1 g) IV slowly, ≤ 1 mmol/min; dilute ≥ 4× in NaCl 0.9% for infusion | central or large vein only: highly irritant, necrosis if extravasated; arrest / peri-arrest use; local vial strength verification needed (UK vials are 14.7% = 10 mmol per 10 mL) |
| oral Caltrate | 600 mg elemental Ca / tablet | 600 mg BD–TDS (1.2–1.8 g/day) with food | separate from levothyroxine, iron, quinolones, tetracyclines by ≥ 2 h |
| oral Caltrate D | 600 mg Ca + 200 IU vitamin D | as Caltrate | vitamin D deficiency usually needs separate loading, not this dose |
| oral Calsyr syrup | 5 mL = 1.435 g Ca glubionate + 0.295 g Ca lactobionate (≈ 108 mg elemental Ca; verify local label) | dose by elemental calcium required | option when tablets not tolerated; local formulation verification needed |
recheck
- hypocalcemia: recheck after IV replacement; repeat if symptomatic or < 1.9 mmol/L
- hypercalcemia: recheck during fluids; senior review if not improving
before leaving
- document: corrected calcium, symptoms, treatment given, response
- pending: PTH / vitamin D / magnesium or malignancy workup as indicated
- hand over: calcium value + trend, next recheck, escalation trigger
MOC pearl
First test after abnormal calcium: PTH. Splits causes into PTH-mediated vs non-PTH-mediated.
evidence
| source | type |
|---|---|
| Denosumab FDA boxed warning, severe hypocalcemia in advanced CKD/dialysis, 2024 | regulatory / safety update |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
free the on-call checklist covers the whole shift on one printable page.
More clinical resources in the MOC+ Library →
reviewed Jun 2026updated Sep 2026file lab/rft-calcium