Quick test interpretation

Here we provide quick guides (tables and algorithms) to interpreting changes in acid-base results from a standard chemistry panel.

Simple disturbances

Respiratory disturbances

The following table provides a summary of the changes in the blood gas (pH, pCO2) with primary respiratory acid-base disturbances, based on the type of disturbance. Note, that a respiratory disturbance cannot be detected from a biochemical panel and a respiratory disturbance does not alter BE.

Disturbance pCO2 Effect on pH
Respiratory acidosis
Respiratory alkalosis

Metabolic disturbances

The following table provides a summary of the changes in the blood gas (pH, HCO3, BE) and biochemical panel (HCO3, AG, Clcorr) with primary metabolic acid-base disturbances, based on the type of disturbance.

Disturbance HCO3
AG Clcorr Effect on pH
Titration metabolic acidosis normal
Bicarbonate loss metabolic acidosis normal
Metabolic alkalosis normal


The table below represents compensatory (secondary) responses to a single primary blood gas disturbance (respiratory or metabolic).  As can be seen, the change in the primary parameter (HCO3for metabolic and pCO2 for respiratory) is paralleled by the compensatory response.

Primary disorder pH [H+] Primary change Compensation
Metabolic acidosis ↓ HCO3 ↓ pCO2
Metabolic alkalosis ↑ HCO3 ↑ pCO2
Respiratory acidosis ↑ pCO2 ↑ HCO3
Respiratory alkalosis ↓ pCO2 ↓ HCO3

Mixed disturbances

Some examples of mixed acid-base disturbances and the changes that ensue are shown in the table below. Note that not all possible combinations are shown in this table.

HCO3 pCO2 AG Clcorr Disorders Expected pH
Primary titration metabolic acidosis (low HCO3  high AG) AND respiratory acidosis (high pCO2) AND primary or compensatory metabolic alkalosis (low Clcorr) N to
(depending on if the alkalosis is primary or secondary)
N N Primary titration metabolic acidosis (high AG) AND metabolic alkalosis (low Clcorr) N, ,
(depends on dominating disturbance)
N Primary metabolic alkalosis (high HCO3, low Clcorr) AND respiratory alkalosis (low pCO2) ↑↑
↓↓ Primary titration AND loss metabolic acidosis (very low HCO3, high AG, high Clcorr), compensatory respiratory alkalosis (low pCO2)

Diagnostic algorithms

 Interpretation of bicarbonate results from a chemistry panel

High bicarbonate
High bicarbonate

Normal bicarbonate
Normal bicarbonate

Low bicarbonate
Low bicarbonate
Interpretation of blood gas results 

Traditional blood gas
Traditional interpretation

Strong ion
Strong ion interpretation


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