Differential Diagnosis

The patient presents with increasing lethargy, disorientation, polydipsia, polyuria, and significant laboratory abnormalities. Considering the patient's history and presentation, the differential diagnosis can be organized as follows:

• Single Most Likely Diagnosis

  • Hyperosmolar Hyperglycemic State (HHS): This condition is characterized by severe hyperglycemia, hyperosmolality, and dehydration, often without significant ketosis. The patient's serum glucose level is not provided, but the presence of polydipsia, polyuria, and a serum osmolality of 321, along with a history of type 2 diabetes mellitus, makes HHS a strong consideration. The patient's altered mental status and dehydration also support this diagnosis.

• Other Likely Diagnoses

  • Diabetic Ketoacidosis (DKA): Although the patient's presentation could suggest DKA, the absence of significant ketosis (not explicitly mentioned) and the higher serum osmolality might lean more towards HHS. However, DKA remains a possibility, especially given the patient's diabetes history and the presence of some degree of acidosis (bicarbonate level of 19).
  • Alcoholic Ketoacidosis: Given the patient's daily alcohol consumption, alcoholic ketoacidosis is a consideration. However, this diagnosis typically presents with a more pronounced anion gap metabolic acidosis and ketosis, which is not clearly evident from the provided information.

• Do Not Miss Diagnoses

  • Sepsis: The patient's elevated leukocyte count (14,000) and hypotension (BP 86/58) could indicate sepsis, which is a life-threatening condition requiring immediate attention. Sepsis can cause or contribute to acute kidney injury (indicated by the elevated creatinine and BUN) and can present with nonspecific symptoms such as lethargy and disorientation.
  • Aspirin Toxicity: Although not directly suggested by the information provided, aspirin toxicity can cause a mixed acid-base disorder and altered mental status. It's crucial to inquire about aspirin use, especially given the patient's history of CAD and HFpEF, for which aspirin might be prescribed.

• Rare Diagnoses

  • Other Causes of Hyperosmolality: While less likely, other conditions that could lead to hyperosmolality, such as hypernatremia or the presence of other osmotically active substances (e.g., mannitol, sorbitol), should be considered if the initial diagnoses are ruled out.
  • Endocrine Disorders: Other endocrine disorders affecting glucose metabolism or fluid balance could potentially present similarly, though they are less likely given the patient's known history of diabetes.