Differential Diagnosis for 52 y/o Male with Diabetes and Alcohol Use Disorder

Single Most Likely Diagnosis

• Chronic Diarrhea: Given the patient's history of alcohol use disorder, chronic diarrhea could be a common issue, leading to low chloride levels due to excessive loss of chloride ions in the stool. Additionally, chronic diarrhea can also lead to a low BUN (Blood Urea Nitrogen) due to decreased absorption of nitrogenous substances.

Other Likely Diagnoses

• Renal Tubular Acidosis (RTA): This condition, often associated with diabetes, can lead to an inability to appropriately acidify the urine, resulting in a loss of chloride ions and potentially low BUN due to impaired renal function.
• Gastrointestinal Bleeding: Although not directly linked to low chloride and BUN, gastrointestinal bleeding is common in individuals with alcohol use disorder and can lead to a decrease in BUN due to less nitrogenous waste being produced from digested blood.
• Malnutrition: Alcohol use disorder can lead to malnutrition, which might result in low BUN due to decreased protein intake and subsequently lower production of urea. Malnutrition can also affect chloride levels indirectly through various metabolic disturbances.

Do Not Miss Diagnoses

• Adrenal Insufficiency: This condition can present with electrolyte imbalances, including low chloride levels, and can be life-threatening if not promptly diagnosed and treated. The low BUN could be indicative of decreased protein metabolism, a feature of adrenal insufficiency.
• Severe Dehydration: Although dehydration typically increases BUN, severe dehydration, especially when associated with significant vomiting (which can occur in alcohol withdrawal), can lead to complex electrolyte imbalances, including low chloride. It's crucial to assess the patient's hydration status carefully.

Rare Diagnoses

• Bartter Syndrome: A rare genetic disorder affecting the kidneys' ability to reabsorb sodium and chloride, leading to low chloride levels. It's less likely given the patient's age and presentation but could be considered in the differential diagnosis if other causes are ruled out.
• Chloride-Losing Nephropathy: Certain conditions can lead to a specific loss of chloride in the urine, which is rare and would typically be considered after ruling out more common causes of electrolyte imbalance.