Determination of Zinc Sufficiency via the Direct Assessment of Fingertip Blood Samples

Abstract

Abstract Zinc (Zn) sufficiency status is commonly determined clinically by serum or plasma zinc concentrations from venous blood collection. To investigate whether the measurement of whole blood Zn concentration using simple and less invasive fingertip blood samples reflects the Zn sufficiency in the body, we first measured the tissue and whole blood Zn concentrations during Zn deficiency and recovery in rats, followed by the same measurements in the fingertip blood samples of young females. Ten microliter of blood sample was diluted, hemolyzed in ultrapure water, and analyzed (50 samples/2 h) without acid digestion or any other pretreatment. Zn restriction in young rats rapidly resulted in Zn deficiency symptoms and a marked decrease in serum Zn concentrations; however, there were no significant changes in Zn concentrations in the liver, muscle tissue, or whole blood from the rat tail vein. In young Japanese women with no health problems (N = 69), average fingertip blood Zn concentration was 793.5 µg/dL (95% confidence interval [C.I.]: 717.0–870.1 µg/dL) and average serum Zn concentration was 76.4 µg/dL (95% C.I.: 78.7–74.2 µg/dL), although no correlation was observed between the two. Average estimated Zn concentration in blood cells was 1271.6 µg/dL (95% C.I.: 1144.0–1399.1 µg/dL), suggesting that individual differences were predominantly influenced by the Zn concentration in blood cells. Whole-blood Zn concentration assay using small amounts of fingertip blood is feasible as a simple evaluation method. Further study will be conducted in all age groups, including males, and the association with variables will be analyzed.