PRL and hyperprolactinemia: A number of studies from the past few years have suggested a major role for PRL in the context of male infertility, but in reviewing existing data involving men undergoing endocrine evaluation for abnormalities in semen parameters, hyperprolactinemia was found in widely varying percentages: from 3.6% for secondary and 8.07% for primary infertility (169), through 12.2% (170), 12.5% (171) to as high as 16.7% (164).