Zonulin, Iron Status, and Anemia in Kidney Transplant Recipients: Are They Related?

Background. In patients after kidney transplantation, anemia is relatively common and is associated with impaired kidney function, subclinical inflammatory state, and immunosuppressive treatment. Zonulin-prehaptoglobin-2, a newly discovered protein, is necessary for integrity of intracellular tight junctions in the gut. Taking into consideration iron metabolism, including its absorption in the gut, we designed a cross-sectional study to look for the possible interactions among zonulin, iron status, and anemia in kidney transplant recipients. Methods. The study was performed on 72 stable kidney transplant recipients and 22 healthy volunteers. Zonulin, iron status, and inflammatory markers were assessed with the use of commercially available kits. Results. Zonulin was significantly lower in kidney allograft recipients than in healthy volunteers (P <.001). Zonulin correlated with systolic blood pressure (r = -0.33; P <.05), thyroid-binding globulin (r = 0.24; P <.05), hematocrit (r = 0.28; P <.005), hemoglobin (r = 0.32; P <.01), total protein (r = 0.33; P <.01), erythrocyte count (r = 0.26; P <.05), and fasting glucose (r = 0.25; P <.05). Zonulin was not affected by sex, type of immunosuppressive therapy, presence of diabetes, coronary artery disease, heart failure, hypertension, or cause of end-stage renal disease. Zonulin was not related to any of the iron parameters studied. In multiple regression analysis, predictors of zonulin were total protein and thyroglobulin-binding protein, explaining 46% of variation. Conclusions. Zonulin, with its poorly defined function, does not seem to play a role in the anemia in kidney allograft recipients; however, it seems to be related to the absorption process in the gut.