PUBLIC LIBRARY / CALCULATOR

Albumin-corrected calcium

Adjusts total calcium for serum albumin: about 40% of calcium is albumin-bound, and hypoalbuminaemia lowers total calcium without changing ionized calcium.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

Simplified adjustment associated with Payne 1973: Ca+0.8×(4−albumin); not measured ionized calcium

The formula in Payne’s 1973 publication was derived from samples with protein abnormalities sent for liver function tests and uses an albumin coefficient of 1, with calcium in mg/100 mL and albumin in g/100 mL. The simplified local variant uses 0.8 and needs its own source for that modification. Adjusted calcium is an estimate, not a measurement of ionized calcium.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Total calcium · mg/dL
Albumin · g/dL

4/4 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

Corrected calcium (mg/dL) = total calcium + 0.8 × (4.0 − albumin in g/dL).

In mmol/L: calcium + 0.02 × (40 − albumin in g/L).

References

Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ, 1973.

Identifier: calcio-corrigido

Original clinical content: Brazilian Portuguese.

Method version

Simplified adjustment associated with Payne 1973: Ca+0.8×(4−albumin); not measured ionized calcium

calcio-corrigido@native-2026-10-05+4eef46fc02f2

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (4)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Total calcium: 7.6 mg/dL
Albumin: 2.5 g/dL

{
  "ca": 7.6,
  "alb": 2.5
}

Expected result

{
  "cac": 8.8
}

Actual result

{
  "cac": 8.8
}

Case 2

reference-002

Inputs

Total calcium: 7 mg/dL
Albumin: 3 g/dL

{
  "ca": 7,
  "alb": 3
}

Expected result

{
  "cac": 7.8
}

Actual result

{
  "cac": 7.8
}

Case 3

reference-003

Inputs

Total calcium: 10.8 mg/dL
Albumin: 3.5 g/dL

{
  "ca": 10.8,
  "alb": 3.5
}

Expected result

{
  "cac": 11.2
}

Actual result

{
  "cac": 11.200000000000001
}

Case 4

reference-004

Inputs

Total calcium: 9 mg/dL
Albumin: 4 g/dL

{
  "ca": 9,
  "alb": 4
}

Expected result

{
  "cac": 9
}

Actual result

{
  "cac": 9
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

README

Local installation

Code license: Apache-2.0

Guidelines and conditions

This repository’s license applies to the code. Third-party instruments, questionnaires, data and models remain subject to their owners’ conditions.

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.