Zinc deficiency: Which matrix should we use?

ABSTRACT

BACKGROUND AND AIM: Zinc is a multifunctional trace element. Due to its positive effects on the immune system, the use of zinc supplements has become widespread during the COVID 19 pandemic Both zinc deficiency and excess intake can lead to significant health problems. In this study;we aimed to compare serum and intra-erythrocyte zinc levels to determine most appropriate matrice in requirement and follow-up of zinc replacement. METHODS: Simultaneously measured serum and intra-erythrocyte zinc levels obtained from 285 patients admitted to our laborotory between 2000-2021 were scanned retrospectively. Atomic absorption spectroscopy method had been used for measurements. Quantitative results of the two different matrices were analyzed by simple linear regression analysis. The agreement between the classifications obtained according to the reference interval was evaluated with kappa statistics. RESULTS: A very weak agreement was observed between intra-erythrocyte and serum zinc measurements according to classification agreement (Kappa statistic=0.000;p=0.994). 149 (59.6%) of 250 results in serum were normal, whereas low in intra-erythrocytes. 6 of results were low in intra-erythrocytes, whereas were high in serum and 2 of results were high in intra-erythrocytes whereas were low in serum samples. The relationship between the measurements of the two matrices was not significant in the linear regression analysis (B=0.011;r=0.106;p=0.073). CONCLUSIONS: These findings indicate that serum measurement may be insufficient to detect zinc deficiency. In the light of these findings, it was decided to study both matrices together in terms of functional target and to follow the clinical correlation in the follow-up of zinc replacement therapy in our laboratory.