Paediatricsmiddle twist
A 14-year-old boy is worried that he is the shortest in his class and has no signs of puberty. His height is on the 3rd centile and his weight on the 10th; his height velocity over the past year has been 4.5 cm. His testes are 3 mL bilaterally with no pubic hair. He can smell normally and has no headaches or visual symptoms. His father says he "was the shortest boy at school and shot up at 16". A bone-age radiograph reads 11 years 6 months. Thyroid function, coeliac serology and full blood count are normal.
Which one of the following is the most likely diagnosis?