Hypocalcemia & Hypercalcemia
at the bedside
- check vitals; symptomatic? acute or chronic?
- correct for albumin, or use ionized Ca on a gas: low albumin makes the total look low
- ECG → low Ca → long QT · high Ca → short QT
- PTH first → it splits the causes
escalate now if
- hypocalcemia → tetany, laryngospasm, seizures, arrhythmia → IV calcium
- hypercalcemia → severe dehydration, altered mental status, arrhythmia, weakness → fluids and bisphosphonate
focused check
- low Ca, causes → thyroid / parathyroid surgery, vitamin D deficiency, CKD, low Mg, high PO₄ / tumor lysis, pancreatitis, sepsis, citrate (transfusion); drugs: bisphosphonates, denosumab, cinacalcet, phenytoin, foscarnet
- low Ca, signs → perioral numbness, cramps, tetany, Chvostek / Trousseau, seizures, laryngospasm
- high Ca, causes → primary hyperparathyroidism, malignancy (PTHrP, bone mets, myeloma), vitamin D excess, granulomas, immobility, thiazides, lithium
- high Ca, signs → dehydration, polyuria, stones, nausea, constipation, confusion, weakness
send now
- corrected Ca = measured Ca + 0.02 × (40 − albumin g/L)
- low Ca → Mg⁺⁺, PO₄, PTH, vitamin D, creatinine
- high Ca → PTH with the same sample, before treatment starts, never delaying it; high or mid-normal → primary hyperparathyroidism; low → PTHrP, 25-OH and 1,25-OH vitamin D, myeloma screen, ALP; creatinine, K⁺
calculator corrected calcium · MDCalc ↗︎
treat
hypocalcemia
tetany, laryngospasm, seizures, long QT, or corrected Ca ≤ 1.9 (ionized ≤ 0.8) after neck surgery
- calcium gluconate 10% 10–20 mL (1–2 g) in 50 mL NaCl 0.9% IV over 10–20 min, monitored; repeat after 10–60 min if symptoms persist; on digoxin → slower, monitor
- still low after boluses (hypoparathyroidism, pancreatitis) → infusion: calcium gluconate 10% 110 mL (11 g) in 1 L NaCl 0.9% at 50 mL/h, Ca every 4–6 h; senior
- replace low Mg⁺⁺ and K⁺ alongside: Ca will not hold otherwise
- corrected Ca 1.9–2.2, no symptoms → Caltrate 600 mg PO BD–TDS with food + vitamin D; Ca at 24 h; not rising → add 1–2 g/day, then IV and think malabsorption
- CKD with high PO₄ → lower the phosphate, do not push IV calcium
hypercalcemia
- stop calcium, vitamin D, thiazides, lithium, vitamin A
- all bands → NaCl 0.9% 1–2 L, then 200–300 mL/h unless heart failure; furosemide only if overloaded
- Ca 2.6–3.0 → fluids, treat the cause
- Ca 3.0–3.5 → fluids, recheck 12 h; symptomatic → treat as severe
- Ca > 3.5, symptomatic at any level, or AKI → fluids + calcitonin 4 IU/kg SC q12h (48 h bridge) + zoledronic acid 4 mg IV over 15 min (works in 2–4 days); senior now
- eGFR < 35 or bisphosphonate failed → denosumab 120 mg SC; severe hypocalcemia risk in CKD, Ca daily
- renal failure + severe Ca → nephrology, dialysis
- hand over → Ca + trend, next check due, escalation trigger
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) in 50 mL NaCl 0.9% IV over 10–20 min; repeat by calcium and ECG (treat) | 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 |
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.
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reviewed Jun 2026updated Oct 2026file lab/rft-calcium