Differential Diagnosis
- Single most likely diagnosis
- Type B lactic acidosis: This diagnosis is the most likely due to the patient's metformin use, which is a known cause of type B lactic acidosis, especially in the setting of renal impairment (stage 3a chronic kidney disease). The patient's high anion gap metabolic acidosis, elevated lactate level, and renal dysfunction support this diagnosis.
- Other Likely diagnoses
- Euglycemic diabetic ketoacidosis: Although the patient has type 2 diabetes mellitus, the absence of ketones in the urine and the presence of a high anion gap metabolic acidosis with an elevated lactate level make this diagnosis less likely.
- Chronic acetaminophen use causing elevated level of 5-oxoproline: The patient's medication list does not mention chronic acetaminophen use, and the laboratory results do not specifically indicate 5-oxoproline elevation.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Salicylate toxicity: Although the patient's blood levels of salicylates were undetectable, it is essential to consider this diagnosis due to its potential severity and the patient's use of aspirin.
- Ethylene glycol ingestion: This diagnosis is crucial to consider due to its severity and potential for high anion gap metabolic acidosis, although there is no specific indication of ingestion in the patient's history.
- Rare diagnoses
- Type A lactic acidosis: This diagnosis is less likely due to the absence of clear tissue hypoxia or hypoperfusion, although the patient does have some signs of hypoperfusion (e.g., low blood pressure).
- Other rare causes of high anion gap metabolic acidosis: These may include conditions like ketoacidosis due to other causes (e.g., alcoholic ketoacidosis), but the patient's presentation and laboratory results do not strongly support these diagnoses.