Serum Indoxyl Sulfate, p-Cresol and β2-Microglobulin in Iraqi Patients on Maintenance Hemodialysis: Circulating Concentrations, Group Separation and the Accompanying Mineral–Bone and Iron Profile

Abstract

Background. Individuals undergoing intermittent hemodialysis, instead of being unburdened from waste products in the body, continue to be in contact with accumulated toxins that vary in size, bind to proteins found in the body, and are also not very soluble in dialysate. Methods. A cross-sectional case-control study was performed for a period ranging from November 2025 to February 2026 at Al-Yarmouk Teaching Hospital in Baghdad, involving 60 stable adult patients undergoing regular hemodialysis and 60 healthy adults. Results. Similarities were observed in terms of age (p = 0.335) and sex (p = 0.461). The body mass index was significantly lower in patients compared to healthy individuals (22.60 ± 4.79 kg/m² vs. 24.91 ± 6.48 kg/m²; p < 0.001). The prevalence of hypertension and diabetes was found to be 76.7 % and 51.7 % in patients tested, respectively. The levels of urea and creatinine were significantly high, while those of the aminotransferases were within normal limits. Mineral bone profile revealed low levels of calcium with high values of phosphorus, alkaline phosphatase, and parathyroid hormone (all p < 0.001). The amount of ferritin was elevated, while transferrin saturation was less than 20 % (both p < 0.001). Indoxyl sulfate (301.77 ± 271.85 ng/mL) has also been identified in patients just as p-cresol (428.34 ± 152.96 pg/mL) and β2-microglobulin (31.51 ± 17.62 mg/L). The values of the area under the curve were quite high for indoxyl sulfate (0.977) and β2-microglobulin (0.961), while being moderately low for p-cresol (0.826).