Lab case 432 interepretation


PH = 7.547 that is moderate alkalaemia.

pCO2 = 24 mmHg, so we have respiratory alkalosis.

Next we will look at the compensation. From the history the case is very unlikely to be chronic. So, we will look at the metabolic compensation for acute respiratory alkalosis.

For acute respiratory alkalosis we expect HCO3 to drop by 2 for every 10 pCO2 below 40.

Accordingly, expected HCO3 should be: 24 – (16 x 0.2) = 20.8. That is very close to the value we have for this patient 21 mmol/L.

It is a good practice to calculate the anion gap for every patient. Anion gap is calculated as: AG = Na – (Cl + HCO3) = 16 for this patient.

This patient has additional HAGMA.

Other abnormal findings:

K = 3.3 mmol/L, that is mild hypokalaemia.

Cl = 107 mmol/L, mild hyperchloraemia.

Glucose = 10.3 mmol/L, that is hyperglycemia (Possibly steroids related or as part of stress reaction).

Lactate = 4.5 mmol/L, that is high.


That patient was hyperventilating which caused the respiratory alkalosis and he was using salbutamol for his asthma. The mechanism behind salbutamol induced hyperlacataemia is still poorly understood. It is suggested that salbutamol diverts the metabolism of pyruvate acid from Krebs cycle toward lactate formation.  ***


Salbutamol-induced severe lactic acidosis in acute asthma.

 2020; 8: 2050313X20969027.
Published online 2020 Oct 28. 
Hamza Najout, Mohamed Moutawakil, Abdelghafour Elkoundi, Nawfal Doghmi, and Hicham Bekkali