Data to assist in the determination of biochemistry test ranges to assess hemodialysis efficacy in patients with chronic renal failure T he concept of a reference interval (RI) in human medicine was developed in the late 1960s by Grasbeck and Saris [1]. An RI is usually defined based on blood samples from healthy men and women, but similar studies of patients could contribute to finding specific values that provide a better ability to discriminate between states of health and disease. Chronic renal failure (CRF) is characterized by a progressive loss of renal function [2]. CRF is associated with increased and decreased levels of some biochemical measurands. RIs based on healthy subjects are not optimal in this clinical context.The objective of this study was to establish expected ranges for biochemical analytes commonly used in the monitoring before and after hemodialysis (HD) in a single laboratory. Materials and Methods Patients and sample collectionThe subjects included in the study were male or female patients of a minimum 18 years of age with diagnosed CRF. A total of 684 patients (aged 18-95 years; 63% male, 37% female) Objectives: Reference intervals are usually defined based on blood samples from healthy subjects and specific reference ranges for patients on hemodialysis (HD) are not currently available. The aim of the study was to establish expected ranges of biochemical analytes before and after HD for patients with chronic renal failure (CRF). Methods: The findings of the 4 most recent quarterly check-ups of 684 patients (233 women and 451 men; age 18-95 years) treated with HD in several dialysis units attached to a single laboratory were studied. Biochemical analytes were measured using fully automated Roche Cobas C 501 or C 701 analyzers (Roche Diagnostics, Basel, Switzerland). Expected ranges were set according to International Federation of Clinical Chemistry and Clinical and Laboratory Standards Institute guidelines using the nonparametric method. Results: Compared with pre-HD values, beta-2 microglobulin (β2m), chloride, creatinine, phosphate, potassium, and urea concentrations were lower post-HD (p<0.001), while bicarbonate, calcium, protein, and sodium concentrations were higher (p<0.001). Comparison with healthy subjects revealed that the levels of β2m, creatinine, and urea were higher before and after HD. Other analyte ranges were either lower, higher, or equivalent to healthy subjects in pre-and post-dialysis measurements. Differences between sexes were not significant, with the exception of creatinine, as well as a significant difference (>10%) in the creatinine level between individuals under and over 60 years of age (p<0.0001). Conclusion:The establishment of specific ranges for dialysis patients could contribute to finding specific thresholds to monitor the effectiveness of HD.