The relationship of serum hepcidin concentration and serum ferritin concentration in VHL^R200W homozygotes and controls. The Spearman correlation between hepcidin and ferritin was 0.68 (P < .0001) in controls and 0.36 (P = .001) in VHL^R200W homozygotes. Forty-four of 90 VHL^R200W homozygotes versus 1 of 50 controls with overlapping serum ferritin concentrations had hepcidin levels that were below the limit of detection, which is consistent with a relationship between VHL^R200W homozygosity and a reduction in hepcidin expression.