DENVER—High and low transferrin saturation (TSAT) levels contribute independently to increased mortality among individuals with normal and reduced kidney function in the general U.S. population, according to researchers.
Austin G. Stack, MD, a Consultant Nephrologist at Letterkenny General Hospital in Letterkenny, Ireland, and collaborators analyzed data obtained from 15,823 subjects aged 20 years and older who participated in the Third National Health and Nutrition Examination Survey (1988-1994). Deaths were ascertained using the National Death Index.
Compared with subjects whose TSAT level was 23.7% to 26.4% (reference group), those with TSAT values in the bottom five deciles (0%-12.5%, 12.5%-16.1%, 16.1%-18.8%, 18.1%-21.3%, and 21.3%-23.7%) had a 2.32, 1.57, 1.44, 1.44, 1.41 times increased risk of death, respectively, after adjusting for demographic factors. Subjects with values in the highest decile (greater than 39.7%) experienced a 1.39 times increased risk of death. The associations between TSAT and mortality did not change after adjusting for comorbid conditions, inflammation markers, and hemoglobin and ferritin levels. The risks associated with low TSAT levels were greatly magnified for those with impaired kidney function. A low TSAT (less than 17.5%) increased mortality risks by more than twofold among those with an eGFR below 60 mL/min/1.73 m2 compared with 1.42 fold among those with an eGFR above 60.
The authors conclude that a more targeted strategy for correcting iron deficiency is warranted in chronic kidney disease and should lead to improved survival. Health professionals should aim for TSAT levels between 23%-40% and avoid over-correction beyond 40%.