PRL and obesity due to melanocortin 4 receptor deficiency: Recent large cohort studies established that, within normal range, low serum PRL is associated with metabolic syndrome and obesity in children (37), and higher prevalence of impaired glucose intolerance, increased insulin resistance, polycystic ovary syndrome (PCOS), nonalcoholic fatty liver disease (NAFLD), and increased risks of new onset T2D in both men and women (11–18).