Differential Diagnosis for Hypoglycemia in an Alcohol-Dependent Woman
Single most likely diagnosis
- Exogenous insulin administration: The presence of increased plasma insulin concentration along with undetectable serum C-peptide concentration during an episode of hypoglycemia strongly suggests the administration of exogenous insulin. As a healthcare worker, the patient would have access to insulin, and the lack of C-peptide, which is typically secreted along with insulin from the pancreas, indicates that the insulin is not endogenously produced.
Other Likely diagnoses
- Factitious hypoglycemia due to sulfonylurea or meglitinide use: Similar to exogenous insulin, these medications can increase insulin secretion and cause hypoglycemia. However, they would typically increase both insulin and C-peptide levels, making this less likely given the undetectable C-peptide in this case.
- Alcohol-induced hypoglycemia: Chronic alcohol use can lead to hypoglycemia, especially in fasting states, due to depleted glycogen stores and impaired gluconeogenesis. However, this typically does not result in increased insulin levels.
Do Not Miss diagnoses
- Insulinoma: Although less likely given the undetectable C-peptide, an insulinoma (a tumor of the pancreas that produces excess insulin) could potentially cause hypoglycemia with elevated insulin levels. However, C-peptide would typically be elevated as well, making this less likely.
- Hepatocellular failure: Advanced liver disease can lead to hypoglycemia due to impaired gluconeogenesis and glycogenolysis. Given the patient's history of alcohol dependence, liver disease is a possibility, but it would not typically cause increased insulin levels.
Rare diagnoses
- Anti-insulin receptor antibodies: These can cause hypoglycemia by activating insulin receptors, but this condition is extremely rare and would be an unusual cause of episodic hypoglycemia.
- Insulin autoimmune syndrome: This involves the production of autoantibodies against insulin, leading to hypoglycemia. It is rare and more commonly associated with other autoimmune conditions. The clinical presentation and lack of detectable C-peptide make this less likely in this scenario.