The diagnosis of 5ARD can be confirmed by mutational analysis of the SRD5A2 gene.
Management of patients with 5ARD is challenging and should have a multidisciplinary approach including the family physician, endocrinologists, clinical geneticists, and psychologists.
The main differential diagnoses of this XY female with normal male testosterone concentration at puberty were CAIS, PAIS, or 5ARD. The USP results of increased etiocholanolone, low androsterone, and extremely low 5[alpha]- to 5[beta]-reduced steroid metabolites ratio were consistent with 5ARD.
has been previously described in 1992 in patients with 5ARD (10).
 Nonstandard abbreviations: hCG, human chorionic gonadotropin; DHT, dihydrotestosterone; USP, urine steroid profile; CAIS, complete androgen insensitivity syndrome; DSD, disorders of sex development; CAH, congenital adrenal hyperplasia; 5ARD, 5areductasetype 2 deficiency.
In these 24 publications, clinical and laboratory data of 149 patients with 5ARD were reported.
From the pathophysiological point of view, measuring the DHT concentration appears to play a central role in the diagnosis of 5ARD. An exaggerated T/DHT ratio has high positive predictive value and appears to be particularly useful in early infants (21).
In view of the above limitations of the DHT test, we resorted to USP and genetic testing for the diagnosis of 5ARD, since both are readily available in our locality.
Although the diagnosis of 5ARD by USP appears straightforward, caution must be exercised when interpreting results for neonates and young infants, since metabolites of cortisol are almost exclusively derived from the 11-oxo metabolite cortisone at this early-stage of life (35).
Instead, mutational analysis of SRD5A2 is the key to the diagnosis of 5ARD. The diagnostic algorithm in Fig.
Nevertheless, for those with both tests performed, the concordance rate is 100%, providing strong evidence that USP is an ideal test for biochemical phenotyping in 5ARD after 3 months of age with the rationale stated above.
In conclusion, 5ARD can be confidently diagnosed by USP from 3 months postnatally and by mutational analysis of SRD5A2.