Lab case 294 interpretation

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Question 1:

PH = 7.3, that is mild acidaemia

HCO3 = 18 mmol/L (<24), so we have metabolic acidosis. Because we have metabolic acidosis then we need to calculate the anion gap and compensation.

Anion gap = Na – (Cl + HCO3) = 20 (>12), so we have anion gap metabolic acidosis.

We calculate the compensation using Winter’s formula. That is expected CO2 = 1.5 x HCO3 +8 (+/- 2). According to that, expected CO2 is between 33 and 37. So the PCO2 here is within the expected range, So we don’t have respiratory component (Well compensated).

Because we have HAGMA it is a good practice to calculate the delta ratio to check if we have an additional metabolic component.

Delta ratio = (AG – 12) / (24 – HCO3) = 1.33 (Ratio between 0.8 and 2) So we have pure HAGMA.

Other abnormal findings:

BSL = 3.2 that is low normal

(In non diabetic patient BSL above 3 is considered normal while in diabetic patient, the level is not normal unless it is above 4 mmol/L).

Ketones = 5, that is very high (We have a state of ketosis)

Next we need to generate a differential diagnosis. We are going to use the easy pneumonic of LTKR.

  •  L for lactate = 1.7 (very slightly elevated and unlikely at that level that is will cause acidosis)
  • T for toxin (usually toxic alcohol), this can be excluded using the osmolar gap. We don’t have user level here however, just calculating Na and glucose we get 291 and serum osmolality is 301. Unlikely we will have a high osmolar gap.
  • K for ketones and the level here is high
  • R for renal (Urea), unlikely to be elevated looking at Cr level and serum osmolality levels.

So most probably high ketones is the cause for this metabolic acidosis. Because the glucose level is toward the low side, most probably we have a case of starvation ketosis.

 

 Question 2:

In starvation ketoacidosis, hepatic glycogen stores are exhausted (usually after 12-24 hours of fasting), the liver produces ketones to provide an energy substrate for the body.

Management of this situation:

  • IV Dextrose, this will lead to increase insulin and decreased glucagon secretion. This will stop ketone production and increase ketone metabolism.
  • Volume resuscitation with Normal saline or lactated ringers.
  • Correct any concomitant electrolyte abnormalities. (Check Mg level)
  • Consider risk of refeeding syndrome.