UKMLA PLAB AMC USMLE Prometric MCQ

 

A 17-year-old girl presents with hypothyroidism. On further questioning it transpires she has primary amenorrhoea. She is also of relatively short stature compared to her sisters. 

What is the most likely diagnosis? 

A. Turner's syndrome 

B. Down's syndrome 

C. Noonan's syndrome 

D. XXX syndrome 

E. Achondroplasia  

Answer: A- Turner's syndrome
Although Turner's syndrome (XO) and Down's and Noonan's syndromes can be associated with short stature and hypothyroidism, Down's syndrome and Noonan's syndrome are not associated with menstrual irregularities. Females with an extra X chromosome (XXX syndrome) are usually tall, whereas individuals with achondroplasia are usually very short; neither condition has an increased incidence of hypothyroidism or menstrual irregularities. The other typical features of Turner's syndrome are cardiac defects (eg coarctation of the aorta), congenital lymphoedema, neck webbing, widely spaced nipples and cubitus valgus. Noonan's syndrome is an autosomaldominant condition (so it affects both sexes), and other typical features include pulmonary stenosis, neck webbing and low-set posteriorly rotated ears