Serum ferritin and iron status in a population of ‘healthy’ 85-year-old individuals

Abstract

Iron status, including S-ferritin, S-iron, S-total iron binding capacity (TIBC), TIBC saturation, haemoglobin (Hb) and dietary iron intake, was assessed in a population study comprising 92 healthy 85-year-old subjects (32 males, 60 females). S-iron, S-TIBC, TIBC saturation and S-ferritin values were not significantly different in the two sexes. Males had a geometric mean S-ferritin of 130 micrograms/l, females of 98 micrograms/l. Ferritin levels less than 15 micrograms/l (i.e. depleted iron stores) were found in one female (1.6%); and in one male (3.1%), who in addition had iron deficiency anaemia. None of the females displayed latent iron deficiency (i.e. S-ferritin less than 15 micrograms/l and S-TIBC saturation less than 15%) or iron deficiency anaemia. Arithmetic mean Hb was 145 +/- 13 (SD) g/l (9.0 +/- 0.8 mmol/l) in males and 139 +/- 11 g/l (8.6 +/- 0.7 mmol/l) in females (p less than 0.02). Median nutritional iron intake was 10 mg/day (range 3-17), higher in males (median 12) than in females (median 9) (p less than 0.0001). Iron intake showed significant correlations to S-iron, S-TIBC and TIBC saturation, but not to S-ferritin.

HFE p.C282Y homozygosity predisposes to rapid serum ferritin rise after menopause: A genotype‐stratified cohort study of hemochromatosis in Australian women

“…A significant correlation (r=0.18) between SF and the number of post-menopausal years in non-blood donors was found. The authors noted similar SF levels were seen when studying healthy 85-year-old women in Copenhagen County (22), and suggested that after 7–10 years of post-menopausal iron accumulation, SF levels stabilise to their new steady-state level and remain fairly constant. This idea has also been put forward by Garry, et al (9) that an individual’s “theoretical setpoint of iron stores” occurs around the age of 40 years for men and after menopause for women.…”

Effect of Serum Heat-Inactivation and Dilution on Detection of Anti-WNV Antibodies in Mice by West Nile Virus E-protein Microsphere Immunoassay

“…Serum dilution, though it contributes to low background signal, can also lead to decrease in sensitivity of the Luminex assay [23] and false-negatives could potentially exist [35]. In the previous studies, WNV E-MIA was conducted at a serum dilution of 1∶100 as it provided low background binding and optimal assay results [8], [10], [11], [36].…”

“…This observed change in MFI may be due to the prozone effect or high-dose hook effect as a result of high antibody titers in serum or the complement interference in the NHI serum. Prozone effect and complement interference in the immunoassays can be eliminated by sufficient dilution of the serum [23], [37], but this can also lead to decrease in sensitivity of the assay, as observed for IgM antibodies (Figure 2A). Therefore, we determined 1∶20 to be the optimal dilution of HI serum for WNV E-MIA that can detect low-titer IgM and IgG antibodies during early and late time-points after infection.…”

“…Complement can interfere in Luminex assays by binding to two or more closely spaced antibodies immobilized on a solid surface, which is only possible in the case of high antibody titers, but not with low antibody titer serum samples [21]. This complement binding blocks the Fc portion of antigen-specific antibodies and competitively prevents the binding of secondary antibodies, eventually giving false-negative results [21], [23], [39].…”

“…Serum dilution, to some extent can eliminate the complement interference or prozone effect observed in the case of high antibody titers, thus can improve the sensitivity of MIA [21]. On the other hand increased serum dilution can lead to decreased sensitivity [23]. WNV E-MIA was conducted at 1∶100 dilution of serum [8], [10], [11], whereas other MIA employed lower serum dilution (1∶20), as it resulted in the low levels of non-specific background with high dynamic range of signal intensities [24], [25].…”