Hello dear user Decrease in body hair can be a sign of testosteron defficency.Other important symptoms and signs of testosteron defficency are :decrease in muscle mass, with an increase in body fat and weight gain ,changes in cholesterol levels,osteoporosis,mild anemia.Serum Testosterone is the authority for Masculine features.The FSH ( Follicular stimulating hormone) stimulate the special cells in the Testes to produce sperms and the another hormone LH ( Luetinizing Hormone) stimulates the special cells to secretes the testosterone hormone.If FSH and LH are not secreted properly this is a condition called hypogonadism.In your cause it can be a male hypogonadism.But tu confirme the diagnose i suggest too meet physically an endocrinologist in your area because it is necessary tu do some specific hormonal tests Hope I have answered your question. If you have any further questions I will be happy to help I wish you good health. Dr. Elona