Changes in osmol gap in chronic kidney disease: an exploratory study

Abstract

Aim: There is no data on osmol gap (OG) in chronic kidney disease (CKD) by stage and limited data on OG in adults on maintenance hemodialysis (HD). We aimed to examine the OG between different stages of CKD and to compare the OG pre- and post-HD in those on maintenance HD. Methods: We conducted a cross-sectional study of 67 patients. The participants were divided into six groups: Group 1—reference group (normal renal function), Group 2—CKD stage 2; Group 3—CKD stage 3; Group 4—CKD stage 4; Group 5—CKD stage 5 and not on dialysis. Group 6 were subjects on maintenance HD. Results: The means of OG ± standard deviation of Groups 1–6 were 15.25 ± 3.0, 20.73 ± 2.68, 22.85 ± 6.99, 24.11 ± 3.64, 25.15 ± 5.06, and 28.88 ± 3.45, respectively (p < 0.001). In the HD group, the difference between the pre-HD and post-HD OG was statistically significant (p < 0.001). Conclusion: There is a statistically significant upward trend for OG as CKD stage increases. The OG is elevated in patients on maintenance HD and is normalized by the HD. OG can be a valuable additional tool to suggest CKD stage and serve as a marker of dialysis adequacy.

• Chronic kidney failure
• end stage renal disease
• osmolality
• osmolarity
• renal dialysis