GHRL and obesity due to melanocortin 4 receptor deficiency: Four studies investigated ghrelin levels in patients with craniopharyngioma (CP) – which is associated with obesity, metabolic syndrome and GH deficiency – and pituitary cancer (Trivin et al. 2009, Holmer et al. 2010, Roth et al. 2011, Roemmler-Zehrer et al. 2014) (Table 1).