Lab Corrections
Lab correction calculators for common adjusted values (e.g., corrected calcium) and formula-based interpretation checks — with worked examples and FAQs.
Corrected Calcium
Adjust calcium for albumin levels for accurate interpretation
Corrected Sodium
Adjust sodium for hyperglycemia to prevent treatment errors
Anion Gap
Calculate anion gap for metabolic acidosis diagnosis
How Lab Corrections Work
Lab "corrections" adjust a reported value using another lab value (e.g., albumin) or a formula to better reflect physiology or compare results consistently.
Inputs must be in the correct units and reference ranges vary by lab; calculators help with arithmetic and consistency.
Common Lab Corrections Explained
Corrected calcium (albumin-adjusted calcium)
Corrected calcium estimates what calcium might be when albumin is low or high. Different labs use different formulas—use the one your service uses.
Example question: Calcium is 2.05 mmol/L and albumin is 25 g/L. What is corrected calcium using a common albumin-adjustment formula?
(40 − albumin) = (40 − 25) = 15
0.02 × 15 = 0.30
Corrected Ca = 2.05 + 0.30 = 2.35 mmol/L
Result: Corrected calcium ≈ 2.35 mmol/L
Tip: Always check your lab's formula and units.
Anion gap
Anion gap is a calculated value from electrolytes. It's often used as a structured check rather than a direct measurement.
Example question: Na⁺ is 140, Cl⁻ is 104, and HCO₃⁻ is 22 (all mmol/L). What is the anion gap?
(Cl + HCO₃) = 104 + 22 = 126
Na − total = 140 − 126 = 14
Report as mmol/L
Result: Anion gap = 14 mmol/L
Tip: Keep all units consistent (mmol/L).
Calculated serum osmolality
Osmolality can be estimated from common labs. Some formulas include urea and some don't—use the local standard.
Example question: Na⁺ is 138 mmol/L, glucose is 5 mmol/L, and urea is 6 mmol/L. Estimate osmolality (mmol/kg) using a common SI formula.
2 × Na = 2 × 138 = 276
Add glucose: 276 + 5 = 281
Add urea: 281 + 6 = 287
Result: Calculated osmolality ≈ 287 mmol/kg
Tip: Pick the SI formula your service uses and stick with it.
When These Calculators Are Used
- •Checking adjusted/calculated values alongside lab reports
- •Reducing arithmetic errors when formulas are used repeatedly
- •Standardising calculations for documentation and handover
- •Education/study for common electrolyte and chemistry relationships
- •Confirming unit consistency before interpreting results
Clinical safety note
Reference ranges and correction formulas can differ between labs and services. Always confirm the formula and units required by your local protocol. These calculators support calculation checking but do not replace clinical judgement. Examples on this page are for calculation practice only.
Related Calculator Categories
Frequently Asked Questions
Always confirm units and the local formula before calculating.