Rosh Psychiatry Board Practice Exam

What is the most useful test to rule out factitious disorder in a patient with hypoglycemia?

1. C-peptide and insulin level

2. Creatinine level

3. Thyroid-stimulating hormone

4. White blood cell count

The correct answer is: C-peptide and insulin level

The most useful test to rule out factitious disorder in a patient with hypoglycemia is the measurement of C-peptide and insulin levels. In cases of hypoglycemia that may arise from factitious insulin use, individuals can present with low blood sugar levels due to the administration of exogenous insulin. When assessing such patients, measuring both insulin and C-peptide levels can help differentiate between endogenous and exogenous insulin production. In the case of factitious disorder, if a patient is self-administering insulin, the C-peptide level would typically be low because the body is not producing the insulin. Conversely, when hypoglycemia is due to the patient's own insulin production (as in insulinoma or other endogenous hyperinsulinemic states), both the insulin and C-peptide levels would be elevated. This distinction is crucial in evaluating the authenticity of the patient's reported hypoglycemic episodes and ruling out factitious disorder. The other tests mentioned, such as creatinine level, thyroid-stimulating hormone, and white blood cell count, are not specific for differentiating between true hypoglycemia and factitious diabetic conditions. They may provide important information regarding general health or rule out other medical conditions but do not directly address the mechanisms behind hypogly