part of part of has part has part has_part characteristic of has modifier testosterone decreased circulating testosterone level MP:0002780 decreased serum levels of testosterone reduced circulating testosterone level reduced serum levels of testosterone reduction in the blood concentration of a potent androgen that promotes development of male secondary sex characteristics and the development of spermatozoa and may regulate sexual desire and help maintain bone and muscle health in both males and females MPheno.ontology abnormal circulating testosterone level decreased circulating hormone level abnormal decreased amount blood