This may be because of the high erythropoietic drive causing severe hepcidin deficiency, which, in turn, leads to iron depletion of macrophages and lowering of the secretion of ferritin.28, 29, 30 The incongruency between LIC and ferritin levels at baseline further highlights the high prevalence of iron overload even in patients who are not regularly transfused, and the importance of iron screening in all patients with PK deficiency.4 Here, HAMP is linked to hyperinsulinemic hypoglycemia, familial, 4.