From the Research
For a patient with recurrent hypoglycemia, normal cortisol, and high TSH who has started levothyroxine, I would not start cortisol supplementation without evidence of adrenal insufficiency. Instead, I would order additional tests including insulin and C-peptide levels to evaluate for insulinoma or inappropriate insulin secretion, sulfonylurea screen to rule out surreptitious use, IGF-1 and growth hormone to assess for growth hormone deficiency, and comprehensive metabolic panel to evaluate liver function. I would also check for antibodies against insulin receptors and consider a 72-hour fasting test to provoke hypoglycemia under controlled conditions. Hypothyroidism can cause hypoglycemia, so optimizing thyroid replacement with levothyroxine may resolve the issue. Starting cortisol without confirmed adrenal insufficiency could cause harmful side effects including immunosuppression, osteoporosis, and metabolic derangements. The patient should be advised to monitor blood glucose regularly, carry fast-acting carbohydrates, and follow up closely to assess response to thyroid replacement therapy.
Some key points to consider in this patient's evaluation include:
- The potential for hypothyroidism to cause hypoglycemia, as noted in the patient's high TSH levels 1
- The importance of confirming adrenal insufficiency before initiating cortisol supplementation, as supported by the study on defective cortisol secretion in response to spontaneous hypoglycemia in neonates with hyperinsulinemic hypoglycemia 2
- The utility of the overnight single-dose metyrapone test as a simple and reliable index of the hypothalamic-pituitary-adrenal axis, as demonstrated in the study on the performance of the overnight metyrapone test 3
- The need to consider other potential causes of hypoglycemia, such as insulinoma or inappropriate insulin secretion, and to evaluate for these conditions through additional testing 4, 5
Overall, a comprehensive evaluation of this patient's condition, including consideration of the potential causes of hypoglycemia and the importance of confirming adrenal insufficiency before initiating treatment, is necessary to provide appropriate care and minimize the risk of harmful side effects.