Lab case 264 interpretation

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Question 1:

PH = 6.94 that is severe a acidaemia

HCO3 = 3, low. So we have metabolic acidosis.

Next we need to calculate anion gap and winter’s formula (compensation).

Anion gap = Na – (Cl + HCO3) = 140 – (110 + 3) = 27 (higher than 12) So we have HAGMA.

Winter’s formula that is expected PCO2 = HCO3 x 1.5 + 8 +/- 2 = 12.5 (+/- 2), very close so we can say that there is no additional respiratory acidosis.

Because we got HAGMA, then we need to calculate the Delta ratio, that is (AG-12/24-HCO3). that is (27 – 12) /  (24 – 3) = 0.71. Value between 0.4 – 0.8 indicate a combined HAGMA and NAGMA.

Other findings:

Cl = 110, that is slightly higher than normal so we have mild hyperchloraemia.

BSL = 27, that is hyperglycemia

Urea and creatinine are elevated so we have additional renal failure

Lactate = 4.6 mmol/L. That is  moderate to severe hyperlactataemia.

Ketones = 6.2, that is high. acceptable level is up to 0.4.

This patient has diabetic ketoacidosis (high BSL, high lactate and high ketones) associated with renal failure.

  Question 2:

  • The BSL level is high, therefore, a correction is required. The formula is:                  [Na+] + (glucose -10)/3 So the corrected Na+ level is 146.
  • K+ increases by 0.6 mmol/L for each 0.1 pH units decrease (and vice versa), PH is reduced by 0.4 (4 times) Accordingly, corrected K will be 4.5 – (4 x 0.6) = 2.1

 Question 3:

  •  Elevated Urea, most propably due to dehydration. That is supported by the Urea/creatinine ratio. (Urea X 1000/ Creatinine) = 125. (ratio more tham 100:1 indicates that the cause is pre-renal).
  • High lactate in patient with DKA is related to anaerobic glycolysis due to inadequate tissue perfusion and oxygenation ( metabolic derangements itself also contributes).
  • High ketones mainly related to insulin deficiency. Without enough insulin, the body breaks down fat as fuel. This leads to the release of free fatty acids from adipose tissue (lipolysis), which are converted through beta oxidation, in the liver, into ketone bodies.

The importance of that is in the management of DKA. So on repeat blood gases, if lactate is not dropping as expected then we need to give N/S bolus. On the other hand, if ketones are not dropping as expected then we need to increase the dose of insulin.