A 54-year-old man presents to clinic with progressive fatigue, weight gain, and decreased libido over the past 6 months. He has a history of Hodgkin lymphoma treated with mediastinal radiation 20 years ago. On examination, he appears lethargic with dry skin and bradycardia (HR 52 bpm). Laboratory studies reveal: TSH 1.8 mIU/L (normal 0.4-4.0), free T4 0.6 ng/dL (normal 0.7-1.9), ACTH 18 pg/mL (normal 7-46), and morning cortisol 6 mcg/dL (normal 8-20). Which of the following is the most likely diagnosis?

  1. A)Primary hypothyroidism from radiation-induced destruction of thyroid follicles
  2. B)Autoimmune thyroiditis triggered by radiation exposure to thyroid tissue
  3. C)Central hypothyroidism due to pituitary dysfunction from radiation exposureGABARITO
  4. D)Secondary adrenal insufficiency with resultant hypothyroid symptoms
  5. E)Thyroid hormone resistance syndrome from post-radiation genetic mutation

Explicação

This patient has central hypothyroidism evidenced by LOW free T4 with INAPPROPRIATELY NORMAL (not elevated) TSH. The critical clue is the low morning cortisol (6 mcg/dL) with normal ACTH, indicating secondary adrenal insufficiency. This pattern of multi-hormon... Ver explicação completa e trilha adaptativa →

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