Reference distributions for serum iron and transferrin saturation: A comparison of a large cohort to the world's literature

Abstract

The appropriate clinical use of serum iron and transferrin saturation (TSAT) requires satisfactory reference intervals from birth to old age, and for males and females. This study identified 54 publications from 1974 to 2001 that met the criteria used in three prior meta-analyses, and these were analyzed statistically. A summary of our review is presented along with our reference population data on these measurements. This analysis places previous publications in perspective and suggests possible reasons for the observed differences. Previous studies of the individual analytes, serum iron, transferrin, and TSAT values agree with the reference ranges presented in this study, although the entire experience over time and between sexes has not been available before. Our 95% reference ranges are somewhat broader than those of the smaller studies, but they agree well with those of the larger ones.

Reference distributions for serum iron and transferrin saturation: a practical, simple, and clinically relevant approach in a large cohort

“…In addition, we did not verify the health status of each referent individual. However, as shown in the companion paper (12) and in our previous publications, the age/gender effects are similar to previously published smaller studies which employed more formal and detailed guidelines to indicate fasting state and health status (35,37), and, in some instances, came from a more diverse population.…”

“…As demonstrated in the companion paper (12), previously published studies gave higher values for the reference interval for reasons that may be related to methodology, but are only partially understood. Figure 2 shows selected serum iron centiles for males (A) and females (B).…”

Pediatric reference intervals for 29 Ortho VITROS 5600 immunoassays using the CALIPER cohort of healthy children and adolescents

“…Unlike statistical significance, wide-spread accepted criteria to judge clinical significance is lacking and is most often based on the judgement of the clinician (22). Additionally, similar to our study, others have demonstrated a small increase in transferrin saturation with age (2,19–21). CALIPER reference values were also similar to those published most recently by Aldrimer, et al, who defined reference intervals for 6 months – 11 years and 12 – 18 years as 6.2%-41% and 6.2%-48%, respectively (21).…”

“…Previous studies also showed a higher transferrin saturation levels in male adolescents (19,20), while others showed no difference (2,21). As iron has been shown to also be higher in males, but transferrin has no apparent sex difference, the transferrin saturation sex difference is most likely a result of higher iron levels in males (4).…”

“…The acute phase response down-regulates the hepatic synthesis of transferrin, therefore decreasing the TIBC, meaning there are less available transferrin binding sites for iron (19). Additionally, inflammation is accompanied by lower concentrations of iron in serum (23).…”