Differential Diagnosis for the Patient's Illness

The patient presents with polyuria, abdominal pain, and a history of alcohol use disorder, among other symptoms. Based on the provided information, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Ethylene Glycol Poisoning: The patient's symptoms, including polyuria, abdominal pain, and the presence of an osmotic gap, along with a history of alcohol use disorder (which might lead to ingestion of substances that resemble alcohol), make ethylene glycol poisoning a strong consideration. The metabolic acidosis with an elevated anion gap further supports this diagnosis.

• Other Likely Diagnoses

  • Diabetic Ketoacidosis (DKA): Although the plasma glucose is 90, which is not typically high enough for DKA, the presence of polyuria, abdominal pain, and metabolic acidosis could still suggest this diagnosis, especially in a patient with newly diagnosed diabetes. However, the absence of hyperglycemia and the specific context of other symptoms and lab results make it less likely.
  • Alcoholic Ketoacidosis: Given the patient's history of alcohol use disorder, alcoholic ketoacidosis is a possibility. However, the lack of significant ketosis (lactic acid is slightly elevated but not indicative of ketoacidosis) and the presence of an osmotic gap make this less likely.
  • Lactic Acidosis: The patient has an elevated lactic acid level, which could be due to various causes including metformin (implying) use, especially in the context of renal impairment (elevated serum creatinine). However, the clinical context and other lab findings do not strongly support this as the primary diagnosis.

• Do Not Miss Diagnoses

  • Salicylate Toxicity: Although not directly suggested by the information provided, salicylate toxicity can cause metabolic acidosis with an elevated anion gap and should be considered in any patient with unexplained acidosis. It's crucial to rule out this condition due to its potential severity.
  • Uremia: The patient's elevated serum creatinine indicates renal impairment. Uremia can cause a variety of symptoms including abdominal pain and could contribute to the patient's metabolic state. While not the most likely cause of the acute presentation, it's an important consideration.

• Rare Diagnoses

  • Methanol Poisoning: Similar to ethylene glycol, methanol poisoning can cause metabolic acidosis with an elevated anion gap and visual disturbances (though the latter is not mentioned). The absence of specific symptoms like visual changes makes this less likely, but it remains a consideration in patients with unexplained metabolic acidosis and a history of substance ingestion.
  • Pyroglutamic Acidemia: A rare cause of high anion gap metabolic acidosis, often associated with acetaminophen use in the setting of malnutrition or critical illness. This diagnosis is less likely given the clinical context but should be considered in refractory cases of metabolic acidosis.