Differential Diagnosis

• Single most likely diagnosis
  • Diabetic Ketoacidosis (DKA): The patient's presentation with vomiting, somnolence, tachycardia, and mild epigastric tenderness, along with laboratory findings of hyperglycemia (elevated serum glucose), metabolic acidosis (low bicarbonate and high anion gap), and elevated serum beta-hydroxybutyrate, strongly suggests DKA. The presence of ketones in the urine further supports this diagnosis.
• Other Likely diagnoses
  • Alcoholic Ketoacidosis: Given the patient's disheveled appearance and the presence of ketones in the urine, alcoholic ketoacidosis is a possible diagnosis. However, the absence of a significantly elevated blood ethanol level and the presence of hyperglycemia make DKA more likely.
  • Dehydration and starvation ketoacidosis: The patient's low BMI and dry mucous membranes suggest dehydration and possible starvation, which can lead to ketoacidosis. However, the presence of hyperglycemia and the specific laboratory findings point more towards DKA.
  • Ethylene glycol or methanol poisoning: Although the patient's metabolic acidosis and elevated osmolal gap could suggest toxic alcohol ingestion, the absence of specific clinical findings (such as visual disturbances or renal failure) and the presence of hyperglycemia make this diagnosis less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: The patient's tachycardia, tachypnea, and hypotension could be indicative of sepsis, particularly in the context of a possible infectious cause of vomiting. Although the patient's temperature is not significantly elevated, sepsis should always be considered in critically ill patients.
  • Acute coronary syndrome: Although the patient is young, his tachycardia and hypotension could be indicative of an acute coronary syndrome, particularly if he has underlying risk factors.
  • Pulmonary embolism: The patient's tachypnea and hypoxia could suggest a pulmonary embolism, which would require immediate attention.
• Rare diagnoses
  • Lactic acidosis due to mitochondrial disorders: Although the patient's serum lactic acid is elevated, this is more likely due to tissue hypoperfusion and DKA rather than a primary mitochondrial disorder.
  • Other rare causes of ketoacidosis, such as fatty acid oxidation disorders: These disorders are rare and typically present in childhood, making them less likely in this adult patient.