<prompt> Estimation of the following hormones is useful while investigating a case of gynecomastia except-TestosteroneProlactinEstradiolLuteinising hormone  <response>: Gynecomastia refers to enlargement of the male breast. It is caused by excess estrogen action and is usually the result of an increased estrogen-to-androgen ratio. True gynecomastia is associated with glandular breast tissue that is 4 cm in diameter and often tender. Evaluation of a case of gynecomastia should include a careful drug history, measurement and examination of the testes, assessment of virilization, evaluation of liver function, and hormonal measurements including testosterone, estradiol, and androstenedione, LH, and hCG. Reference : page 2366 Harrisons Principles of Internal Medicine 19th edition . 