Circadian variations of transferrin saturation levels in iron‐overloaded patients: implications for the screening of C282Y‐linked haemochromatosis

The phenotypic screening for genetic haemochromatosis (GH) relies upon the determination of transferrin saturation (TS). In large‐scale screening programs, the time of blood sampling can be uneasy to control. We studied the circadian variations of TS at 08·00 hours, 12·00 hours, 18·00 hours and 00·00 hours in 46 C282Y homozygous patients (GH) and 47 non‐GH patients (NH), to determine whether the time of blood sampling influenced the results of screening. In both groups, there were significant circadian variations in TS, with the highest values at 08·00 hours and the lowest at 00·00 hours. For any given time‐point, TS was significantly higher in the GH group when compared with the NH group (P