1. Draw the hypothalamic-pituitary-thyroid axis, showing negative feedback control points.
2. A TRH stimulation test involves measuring basal TSH levels and then measuring again after an injection of TRH. This test is often not necessary for thyroid patients, but would it be beneficial in diagnosing Barbara's condition? (Barbara has low TSH, T3, T4).
3. Extrapolate the knowledge you have of the hypothalamic-anterior-pituitary-thyroid axis to explain how anabolic steroid abuse would lead to testicular atrophy.