Severe metabolic acidosis in the alcoholic: differential diagnosis and management

1 A chronic alcoholic with severe metabolic acidosis presents a difficult diagnostic problem. The most common cause is alcoholic ketoacidosis, a syndrome with a typical history but often misleading laboratory findings. This paper will focus on this important and probably underdiagnosed syndrome.

2 The disorder occurs in alcoholics who have had a heavy drinking-bout culminating in severe vomiting, with resulting dehydration, starvation, and then a β- hydroxybutyrate dominated ketoacidosis.

3 Awareness of this syndrome, thorough history-taking, physical examination and routine laboratory analyses will usually lead to a correct diagnosis.

4 The treatment is simply replacement of fluid, glucose, electrolytes and thiamine. Insulin or alkali should be avoided.

5 The most important differential diagnoses are diabetic ketoacidosis, lactic acidosis and salicylate, methanol or ethylene glycol poisoning, conditions which require quite different treatment.

6 The diagnostic management of unclear cases should always include toxicological tests, urine microscopy for calcium oxalate crystals and calculation of the serum anion and osmolal gaps.

7 It is suggested here, however, that the value of the osmolal gap should be considered against a higher reference limit than has previously been recom mended. An osmolal gap above 25 mosm/kg, in a patient with an increased anion gap acidosis, is a strong indicator of methanol or ethylene glycol intoxication.