Differential Diagnosis

The provided laboratory results show hyponatremia (sodium 128), hyperglycemia (glucose 221), hypochloremia (chloride 92), and a low bicarbonate level (CO2 22). Based on these findings, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Diabetic Ketoacidosis (DKA): This condition is characterized by hyperglycemia, which is present in this case. The low sodium and chloride levels, along with the low bicarbonate, can be seen in DKA due to the metabolic acidosis and possible dehydration.

• Other Likely Diagnoses

  • Hyperosmolar Hyperglycemic State (HHS): Similar to DKA, HHS presents with hyperglycemia but typically without significant ketosis. The electrolyte imbalances and low bicarbonate level could be consistent with HHS, especially in the context of severe dehydration.
  • Adrenal Insufficiency: This condition can lead to hyponatremia and hypochloremia due to the lack of aldosterone, which regulates electrolyte balance. Hyperglycemia might not be a direct result but could be seen in the context of critical illness.
  • Severe Dehydration: Dehydration, especially when severe, can lead to electrolyte imbalances, including hyponatremia and hypochloremia. The hyperglycemia could be stress-induced or due to underlying conditions like diabetes.

• Do Not Miss Diagnoses

  • Septic Shock: Although not directly indicated by the electrolyte panel, septic shock can cause a wide range of electrolyte disturbances due to fluid shifts, organ dysfunction, and the stress response, which includes hyperglycemia. Missing this diagnosis could be fatal.
  • Acute Kidney Injury (AKI): AKI can lead to electrolyte imbalances, including hyponatremia and hypochloremia, due to the kidney's inability to properly regulate electrolytes. The low bicarbonate could indicate a metabolic acidosis, which is common in AKI.

• Rare Diagnoses

  • Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): This condition can cause hyponatremia due to excessive water retention. However, it typically presents with euvolemia or mild hypervolemia and might not directly explain the hyperglycemia or the specific pattern of electrolyte imbalance seen here.
  • Cushing's Syndrome: This rare endocrine disorder can lead to hyperglycemia due to excess cortisol. Electrolyte imbalances can occur but are less characteristic of the primary presentation.