Clinical_Rounds_in_Endocrinology_Volume_II_-_Pediatric_Endocrinology

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Parameters PAIS

5 α-reductase

type 2 17 β-HSD3 defi ciency

Prostate Normal/hypoplastic Hypoplastic Normal/hypoplastic

Gynecomastia Present Absent Present

Facial hair Reduced Reduced to

absent

Reduced

Temporal recession May be present Absent May be present

Gonads Inguinal/scrotal Inguinal/scrotal Intra-abdominal/inguinal

Basal testosterone Normal to elevated Normal to

elevated

Low

LH and FSH Normal to elevated Normal to

elevated

Elevated

hCG stimulation

test

• T/DHT ratio

  
  

  10

  
  

  
  

T/A ratio <0.8

Sex of rearing

(commonly)

Male Female Female

Sex reversal (if

reared as female)

Uncommon Common Common

Therapy High-dose androgens High-dose

androgens

Topical DHT

gel

Gonadectomy and estrogen,

if reared as female

Androgen, if reared as male

54. A 20 - year - old individual who was reared as male presented with poor facial
    hair and genital ambiguity. The clinical profi le of the patient is depicted below.
    What are the differential diagnoses in the index case?

The index patient had immature facies and poor facial hair suggestive of hypo-

gonadism. Genital examination revealed Tanner pubic hair stage P 4 , bilateral

scrotal testes (size 6 ml each), microphallus (stretched penile length 5 cm),

ventral–urethral groove, and penile hypospadias. The external masculinization

score was 7. He did not have gynecomastia. Since both the gonads were pal-

pable, a clinical diagnosis of 46,XY DSD was considered. The differential

diagnosis in this individual includes androgen biosynthetic defects (ABSD),

partial androgen insensitivity (PAIS), and 5α-reductase type 2 defi ciency. In

the index patient, biochemical evaluation revealed serum testosterone

24 nmol/L, LH 7μIU/ml, and FSH 18.8 μIU/ml. As serum testosterone is in the

upper normal range, a diagnosis of ABSD is unlikely. Hence to differentiate

between partial androgen insensitivity (PAIS) and 5α-reductase type 2 defi -

ciency, a hCG stimulation test was performed. The stimulated testosterone/

dihydrotestosterone ratio was 4.9. Absence of gynecomastia in the index

patient favors a diagnosis of 5α-reductase type 2 defi ciency, whereas a T/DHT

ratio of 4.9 makes this diagnosis unlikely. High-normal serum testosterone and

LH and T/DHT ratio of 4.9 suggest a diagnosis of PAIS, although absence of

gynecomastia is uncommon in PAIS. High FSH in the index patient represents

either germ cell failure or it may be a manifestation of decreased testosterone

9 Disorders of Sex Development