Y M is a boy who presented at the age of 5.5 years with slow growth He had a birth weight = 3.1 kg and length = 49.5 cm. Infantile and early neonatal periods are uneventful. He had normal development and appropriate nutritional history. No family history of endocrinopathy and/ or short stature was reported. His measurements were: weight= 16.9 kg, Height = 104 cm (HtSDS = -1.8), growth velocity (GV = 1 cm/y) and BMI= 16 and mid-parental height (MPHt) SDS = -0.6. He had no dysmorphic features, skeletal anomalies, goitre or pigmentation. The rest of the examination was unrevealing.
Investigations showed normal CBC, ESR, and liver and renal and thyroid functions. Sweat chloride test, and tissue trans-glutaminase concentrations were normal. His IGF-I level = 70 (IGF-I SDS = -1) and his bone age = 3 years. The peak GH response to clonidine stimulation test = 10 ng/dl. Brain MRI showed normal pituitary gland.
Because of the decelerated growth and marginally low IGF-I a trial of GH therapy was started (0.035 mg/kg/day s.c. HS). A rapid catch-up of growth occured during the first 3 years of treatment that was maintained at a slower pace during the following 5 years. Testicular enlargement started at 11 years and at 12 years his HtSDS = 0.8 and bone age = 12.5 years. His predicted adult height = 181 cm.
Conclusion Prolonged GH treatment of this boy (normal GH-IGF-I axis) with GH unexpectedly resulted in a HTSDS which surpassed his MPHtSDS by 1.4 SD.