RESUMEN
AIM: We examined the circulating levels of iron and ferritin in serum of seven healthy and three insulin non-dependent diabetic (Type 2) males in order to compare their circadian characteristics. METHODS: Blood samples were collected every 3h over a 24h period and were analyzed for serum iron and ferritin. RESULTS: The mean Fe level was significantly higher in healthy than in diabetic subjects: 80.0 +/- 3.3 vs. 63.0 +/- 3.7 microg/dL. The ferritin level was significantly lower in healthy than in diabetic men: 79.8 +/- 4.7 vs. 186.3 +/- 110.5 microg/L. A significant (p < 0.001) time-effect was found by ANOVA and circadian rhythm was detected at p < 0.001 in all data sets when a 24h cosine was fitted to the normalized data. Acrophases were located in mid to late morning for Fe (11:30, vs. 09:22h) and for ferritin (11:10 vs. 11:46h). DISCUSSION: We concluded that there is significant circadian variation in both serum Fe and ferritin, with predictable peaks in the mid to late morning.