Assessment of the gonadotrophin-gonadal axis in androgen insensitivity syndrome

Objective-To study the value of measuring serum luteinising hormone (LH), f ollicle stimulating hormone (FSH), testosterone, and dihydrotestosterone (D HT) in androgen insensitivity syndrome (AIS). Design-Retrospective study of patients on a nationwide register of AIS. Patients-Sixty one cases of AIS with androgen receptor (AR) dysfunction (ab normalities of the AR gene and/or abnormal AR binding) were divided into th ree age groups: infants, < 1 year old; children, 1-13 years old; and postpu bertal, > 13 years old. Measurements-Age, dose of human chorionic gonadotrophin (hCG) stimulation, pre-hCG and post-hCG serum testosterone values, serum DHT values, and serum LH and FSH values before and after LH releasing hormone (LHRH) stimulation . Results-In 23 of 30 infants testosterone was within age related reference r anges; six were above this range. The median testosterone rise following va riable dosage of hCG was 9.5 times the basal value,The increment was not re lated to the hCG dose, age, or basal concentration of testosterone. The med ian basal and stimulated testosterone:DHT ratios were 2.5 and 6.1, respecti vely. The median increment in DHT was 2.2-fold. Seventeen of 18 FSH and 11 of 19 LH measurements were within age related ranges in infants; in seven p atients LH values were above the range. LHRH stimulation performed in 39 pa tients showed an exaggerated LI-I in all age groups. The FSH response was n ot exaggerated in children. Conclusion-Although a positive hCG test excludes biosynthetic defects of te stosterone, an inadequate response does not exclude AUS. Basal LH and testo sterone may not be raised during early infancy. An LHRH stimulation test mi ght be useful for evaluating cases of suspected AIS presenting in mid-child hood.