Hormonal changes in 3-month-old cryptorchid boys

Context: Hormonal dysregulation has been suggested to be one of many etiological factors of cryptorchidism. Objectives: The objective of this study was to assess the hypothalamic-pituitary-testicular axis in cryptorchid boys during the postnatal hormonal surge. Design: This was a prospective, longitudinal, population-based study. Setting: The study was performed at two primary obstetric centers. Participants: Study participants included 388 Finnish and 433 Danish boys (88 and 34 with cryptorchidism, respectively). Interventions: Clinical examinations were performed at 0 and 3 months. Blood samples were taken at 3 months. Main Outcome Measures: The main outcome measures were testis position and reproductive hormone levels. Results: Finnish cryptorchid boys had significantly higher FSH [1.59 (0.50-3.53) vs. 1.30 (0.49-2.92) IU/liter; P < 0.0001] and lower inhibin B[ 426 (254-770) vs. 459 (266-742) pg/ml; P < 0.015] levels than Finnish control boys [median (2.5th-97.5th percentiles)]. Danish cryptorchid boys had higher FSH levels than controls [1.47 (0.54-3.89) vs. 1.18 (0.41-3.04) IU/liter; P = 0.018]. Inhibin B levels in healthy Danish boys were lower than those in Finnish boys [380 (233-637) pg/ml; P < 0.0001] and were not reduced in Danish cryptorchid boys [392 (236-672) pg/ml; P = 0.851]. Changes in hormone levels were strongest in boys with severe, persistent cryptorchidism, but were also detectable in mild and transient cryptorchidism. Effects on Leydig cell function were subtle, with an increase in LH in Finnish ( but not Danish) cryptorchid boys vs. controls [1.97 (0.77-5.91) vs. 1.75 (0.58-4.04) IU/liter; P < 0.021], but testosterone levels remained within the normal range. Conclusions: Our results support the hypothesis that cryptorchidism is associated with a primary testicular disorder, which could be a cause or a consequence of cryptorchidism. This malfunction is reflected by low inhibin B production in the Finnish cohort and high gonadotropin drive in both the Finnish and Danish cohorts.