Lab case 369 interpretation

PH = 7.294, that is moderate acidaemia (very close to be mild) – PH down to 7.3 is considered mild.

HCO3 = 6 mmol (Less than 24) so we have metabolic acidosis. Because we have metabolic acidosis, then we need to calculate both the anion gap and the respiratory compensation for this patient.

Anion Gap = Na – (Cl + HCO3) = 133 – (108 +6) = 19, so we have HAGMA.

To calculate the compensation for this patient we use Winter’s formula. That is Expected pCO2= 1.5 x HCO3 + 8 (+/- 2), accordingly, expected pCO2 is 15 -19. Since this patient’s pCO2 is less than that (13.4) then this patient has additional respiratory alkalosis.

Because we have HAGMA we will calculate the delta ratio to exclude the presence of an additional metabolic process.

Delta ratio is calculated as (AG – 12) / (24 – HCO3) = 0.38. That is consistent with pure NAGMA.??

  • 0.4 = normal anion gap metabolic acidosis
  • 0.4-0.8 = mixed high and normal anion gap acidosis.
  • 0.8-2.0 = pure high anion gap metabolic acidosis
  • Over 2.0 = high anion gap acidosis with pre-existing metabolic alkalosis.

Other abnormal findings,

The most obvious abnormality is high ketones level of 7 mmol/L. that is hyperketonaemia.

Blood glucose = 10.4, that is hyperglycemia (mild).

Lactate = 2.8, that is mild hyperlactataemia.

(This patient has high glucose level, high lactate and high ketones in the presence of acidosis, this fits the definition of DKA).

Na level is slightly low – mild hyponatraemia

Cl level is mildly elevated – hyperchloraemia.

This patient has DKA due to SGLT2 inhibitors intake. SGLT2 inhibitors work by reducing renal tubular glucose reabsorption, leading to a reduction in blood glucose without stimulating insulin release. They also enhance lipolysis and hyperglucagonaemia. This will lead to Ketosis and Hyperketonaemia with normal sugar levels. (Euglycemic DKA.)

Acidosis caused by hyperketonaemia is usually mild, this is related to the PH of ketones.

Acidosis caused by elevated ketones levels is usually mild as the average PH of ketones is 5.8. (Average PH of lactate that is 2.4)

Because the acidosis caused by ketosis is mild the body can tolerate it for a longer time given time to renal compensatory mechanism to correct the acidaemia, that is usually done by re-absorption of Cl. That is why delta ratio shows pure NAGMA.

This is a case of chronic HAGMA.


Special thanks to Dr Paul Koh for providing the details of this case