Pituitary abnormalities in Prader-Willi syndrome and early onset morbid obesity

Prader–Willi syndrome (PWS) is a well‐defined syndrome of childhood‐obesity which can serve as a model for investigating early onset childhood obesity. Many of the clinical features of PWS (e.g., hyperphagia, hypogonadotropic hypogonadism, growth hormone deficiency) are hypothesized to be due to abnormalities of the hypothalamus and/or pituitary gland. Children who become severely obese very early in life (i.e., before age 4 years) may also have a genetic etiology of their obesity, perhaps with associated neuroendocrine and hypothalamo‐pituitary defects, as infants and very young children have limited access to environmental factors that contribute to obesity. We hypothesized that morphologic abnormalities of the pituitary gland would be seen in both individuals with PWS and other subjects with early onset morbid obesity (EMO). This case‐control study included individuals with PWS (n = 27, age 3 months to 39 years), patients with EMO of unknown etiology (n = 16, age 4–22 years; defined as body mass index greater than the 97th centile for age before age 4 years), and normal weight siblings (n = 25, age 7 months to 43 years) from both groups. Participants had 3‐dimensional magnetic resonance imaging to evaluate the pituitary gland, a complete history and physical examination, and measurement of basal pituitary hormones. Subjects with PWS and EMO had a higher prevalence of pituitary morphological abnormalities than did control subjects (74% PWS, 69% EMO, 8% controls; P