Pituitary size in patients with Laron syndrome (primary GH insensitivity)

OBJECTIVE: The purpose of the present study was to investigate whether lifelong secretion of high levels of GH, characteristic of Laron syndrome, leads to an increase in the size of the pituitary gland. METHODS: Eleven patients (six females, five males) with Laron syndrome underwent magnetic resonance imaging of the pituitary region with a system operating at 0.5 T. There were nine adults aged 36-68 Years and two children, a 4-Year-old boy and a 9-Year-old girl. The latter patient had been treated with IGF-I (150-180 mg/kg per day) since the age of 3 Years; all the other patients were untreated. The height of the adenohypophysis was measured on the sagittal images and compared with reference values for age and sex. RESULTS: The height of the adenohypophysis was within the normal range for age and gender in all patients, except for one male, who had a small gland. No congenital anomalies of the pituitary-hypothalamic region were detected. CONCLUSION: Despite the lifelong high levels of GH, no pituitary hypertrophy was detected. The anatomy of the pituitary-hypothalamic region in Laron syndrome is normal.