Differential Diagnosis for Elevated LH, TT, and SHBG with Normal Free T

• Single most likely diagnosis:
  • Hyperthyroidism: Elevated SHBG and LH can be seen in hyperthyroidism due to the increased production of thyroid hormones, which can affect sex hormone-binding globulin (SHBG) levels and potentially disrupt the normal feedback mechanisms involving LH and testosterone (TT). The normal free testosterone (free T) level in this context might seem counterintuitive but can occur due to the complex interplay between thyroid hormones, SHBG, and sex hormones.
• Other Likely diagnoses:
  • Polycystic Ovary Syndrome (PCOS): Although more commonly associated with women, some features of PCOS, such as hormonal imbalances, can present with elevated LH levels. However, the typical presentation includes elevated androgen levels, which might not align perfectly with normal free T unless the androgen excess is mild or compensated.
  • Thyroid Hormone Resistance: A rare condition where the body's tissues are resistant to thyroid hormones, potentially leading to elevated levels of these hormones and secondary effects on other hormonal pathways, including sex hormones.
• Do Not Miss diagnoses:
  • Testicular Cancer: Certain types of testicular cancer, particularly those affecting the Leydig cells (Leydig cell tumors), can produce excess testosterone and potentially affect LH levels due to feedback mechanisms. Although rare, missing this diagnosis could have significant consequences.
  • Adrenal Tumors: Tumors of the adrenal gland can produce excess androgens, potentially affecting LH and testosterone levels. Early detection is crucial for effective management.
• Rare diagnoses:
  • Congenital Adrenal Hyperplasia (CAH): A group of inherited disorders that affect the adrenal glands, leading to imbalances in the production of various hormones, including sex hormones and cortisol. Some forms of CAH could potentially present with the described hormonal profile, although it would be uncommon.
  • Idiopathic Hyperandrogenism: A condition characterized by excess androgen production without an identifiable cause. It might present with elevated LH and testosterone levels, although the normal free T level might not typically align unless there's a compensatory mechanism involved.