Clinical_Rounds_in_Endocrinology_Volume_II_-_Pediatric_Endocrinology

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37. A 6 - day - old newborn presented with genital ambiguity. On examination , exter-
    nal genitalia was Prader stage 3 and gonads were non - palpable. Karyotyping
    is awaited. How to proceed?

ACTH-stimulated serum 17(OH)P and karyotyping are the fi rst-line investiga-

tions in the evaluation of a child with genital ambiguity and non-palpable

gonads. CAH due to 21α-hydroxylase defi ciency is the most common differen-

tial diagnosis in this scenario and early diagnosis and timely initiation of

therapy may prevent salt-wasting crisis. As the results of karyotyping and

serum 17(OH)P are not immediately available, ultrasonography can be used to

evaluate the presence/absence of Mullerian derivatives (uterus, fallopian tubes,

and upper two-thirds of vagina). Presence of Mullerian derivatives in a child

with genital ambiguity and non-palpable gonads increases the likelihood of

CAH; therefore, blood pressure, serum sodium, potassium, and blood glucose

should be closely monitored, and glucocorticoid therapy should be initiated, if

required. The defi nitive diagnosis in the newborn can be established once

results of karyotype and 17(OH)P are available.

Ambiguous genitalia with non-palpable gonads

ACTH-stimulated 17-OHP

Karyotyping

46XX/46XY

17-OHP<2ng/ml

46XX

17-OHP

>100ng/ml

17-OHP

10- 100ng/ml

17-OHP

<2ng/ml

OT-DSD • 46XY partial GD

• 17α-hydroxylase
  deficiency

MGD

• CAH 21α-
  hydroxylase
  deficiency
  
  
  • 11β –hydroxylase
    deficiency
  
  
  • POR deficiency
    
    
    • OT-DSD
    
    
    • Exogenous
      androgen exposure
    
    
    • Placental aromatase
      deficiency
    
    
    
    
  
  
  
  

46XY

17-OHP <2ng/ml

45X/46XY

17-OHP <2ng/ml

Fig. 9.13 Approach to a child with genital ambiguity and non-palpable gonads

9 Disorders of Sex Development