Accumulation of toxic metals in ectopic endometrial tissue

Abstract

INTRODUCTION AND OBJECTIVES: Aim of this study was to determine the association between heavy metals and endometriosis. METHODS: A case-control study was conducted in a tertiary care hospital comparing 50 cases of endometriosis with 50 age matched controls confirmed by laparoscopy or laparotomy. Blood samples and ectopic endometrial tissue samples were obtained and digested with supra pure 65% HNO3. Samples were analysed for cadmium by graphite furnace atomic absorption spectroscopy (GFASS). In a subset of cases (n=30) and controls (n=40) samples were analyzed for nickel, lead and zinc by Total Reflection X-ray Fluorescence (TXRF) technique. T-tests and Spearman's correlation coefficient were used for analysis. RESULTS: Cases had significantly higher (p=0.011) mean (+SD) blood nickel levels (1.69+1.18 ug/1) as compared to controls (0.96+0.94 ug/1). Blood levels of cadmium (0.75±0.46 ug/I vs 0.77 ±0.37 ug/1) lead (5.8S±1.25 ug/1 vs 3.45±1.25 ug/1) and zinc (123.02±2.49 ug/1 vs151.35 ±2.46 ug/1) were similar in the two groups (p=0.289, p=0.123s and p=0.339, respectively). Tissue samples had significantly higher (p=0.001, p<0.001, p=0.049 respectively) mean (+SD) levels of cadmium (2.86±0.61 ug/1 vs 0.8±0.48 ug/1) nickel (8.64±0.4.12 ug/Lvsl.58±1.21ug/l) and lead (11.22±4.67 ug/1 vs 5.86±3.38 ug/1) compared to blood levels. Mean (+SD) blood levels of zinc (117.48 ±2.64 ug/1) was higher (p<0.001) than that in tissues (27.54±6.65 ug/1). There was a positive correlation between blood zinc levels and tissue zinc levels (r=0.417;p= 0.034) but there was no correlation between blood and tissue levels of cadmium, nickel and lead (r=0.237,p=0.085; r=0.372,^=0.113; r=0.70,/?=0.067, respectively). CONCLUSIONS: Cadmium, nickel and lead but not zinc accumulate in ectopic endometrial tissue.