ABSTRACT
PRIMARY, SECONDARY, OR MIXED HYPOGONADISM The classification of hypogonadism into primary or secondary etiology is defined by the level within the hypothalamicpituitary-testicular axis that malfunctions. Levels of luteinising hormone (LH) are the simple laboratory assessment that clarifies the etiology. If testosterone is low and LH is high, the condition is classified as primary hypogonadism; if LH levels are low, it is classified as secondary hypogonadism. A common clinical situation in elderly men is the presence of midnormal LH levels and low testosterone levels indicating an inability of the pituitary to respond to the low testosterone level. This could be regarded as an insufficient hypothalamic or pituitary response to a low circulating testosterone level and thus a secondary hypogonadism. At the same time the testicular response to LH stimulation may be weakened indicating a primary component. These cases may be referred to as a state of mixed hypogonadism with both a primary and a secondary component. Although a substantial number of middle age and elderly men presents with the sign of classical primary hypogonadism i.e. low testosterone and elevated LH levels (EMAS study).
