Bioactive Luteinizing Hormone and Idiopathic Oligospermia

Idiopathic oligospermia (10), defined as oligospermia associated with normal peripheral concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) is common in infertile males.' Not infrequently, basal serum gonadotropin concentrations are in the upper range of normal, whereas peripheral T concentrations are either in the normal or low normal range.2*3 The pathophysiology of I 0 is poorly understood, and disordered gonadotropin secretion has been proposed as a possible mechanism. An increased LH pulse amplitude has been demonstrated in 10, implying an abnormality in gonadotropin release as either a primary or secondary p h e n ~ m e n a . ~ One of the possible mechanisms that could theoretically account for this altered gonadotropin pattern includes an inherent abnormality of the LH molecule secreted with diminished bioactivity, resulting in a compensated increase of immunoactive LH secretion in order to maintain T secretion. As hypogonadism, associated with immunologically detectable LH without biological activity, has been de~c r ibed ,~ an inappropriate proportion of bioactive LH (LH-b) and irnmunoactive LH (LH-i) could possibly be present in some males with 10.