DENVER—Changes in interdialytic weight are associated with reciprocal changes in both serum hemoglobin (Hb) and, consequently, doses of erythropoietin-stimulating agents (ESAs), according to researchers.
“The hypothesis is that dilution occurs in the serum and it has a measurable effect on the [Hb] test result,” said lead researcher Joe Weldon, MBA, Associate Director of Medical Informatics at DaVita Clinical Research in Minneapolis.
As a result of the study findings, clinicians may want to consider the amount of interdialytic fluid gain or loss when interpreting Hb test results.
Weldon and his colleagues reviewed data from 164,866 hemodialysis patients who dialyzed between January 1 and December 31, 2009. Patients who experienced an interdialytic weight gain greater than 2.0 kg but not more than 10 kg had a mean 0.29 g/dL decline in Hb that triggered a 6.8% increase in weekly ESA dose, the researchers reported. Patients who experienced a 0.5 to 2.0 kg increase in interdialytic weight had a mean 0.09 g/dL rise in Hb and a resulting 1.0% increase in weekly ESA dose. Conversely, subjects who had an interdialytic weight loss of 0.5 to 2.0 kg experienced a 0.23 g/dL rise in Hb and a 2.5% concomitant decrease in weekly ESA dose. Patients with an interdialytic weight loss greater than 2.0 kg but not more than 10 kg had a mean 0.39 g/dL rise in Hb and a concomitant 0.4% increase in weekly ESA dose.
Changes in pre-dialysis weight, which may be a surrogate for fluid status, were associated with reciprocal changes in both Hb and, in sequence, ESA dose, the authors noted in their poster presentation.
“Given the magnitude of these effects, changes in pre-dialysis weight may be a clinically meaningful confounder of the relationship between Hb, ESA dose, and morbidity and mortality in dialysis patients,” they concluded.