46, XX male disorder of sexual development

Presentation 

A 47-year-old male was referred to endocrinology with a 9-year history of primary hypogonadism. Baseline testosterone was 4.3 nmol/L (RR 8-30) with an elevated follicle stimulating hormone (17.5 IU/L) and luteinizing hormone (15.2 mIU/ml). He had a short stature with bilateral small pre-pubertal testicles. 

Diagnosis 

Karyotyping showed 46 XX, making a diagnosis of 46, XX male disorder of sexual development. Fluorescence in situ hybridization analysis identified the presence of a translocated sex-determining region Y gene. 

Treatment 

Testosterone replacement therapy (testogel). Monitoring blood markers affected by testosterone therapy and metabolic risk factors. 

Conclusion 

Primary hypogonadism in males can be divided into congenital and acquired causes. 46, XX male disorder of sexual development is a rare congenital cause, with an incidence of approximately 1 in 20,000 newborn males. This case report highlights the value of karyotyping in the workup for primary hypogonadism.