Association between common iron store markers and hemoglobin in children with chronic kidney disease
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Serum ferritin and transferrin saturation (TSAT) are used to assess iron status in children with chronic kidney disease (CKD), but their sensitivity in identifying those at risk of lower hemoglobin (HGB) values is unclear.
We assessed the association of iron status markers (ferritin, TSAT, and serum iron) with age- and gender-related HGB percentile in mild-to-moderate CKD in 304 children in the Chronic Kidney Disease in Children (CKiD) Study. Standardized HGB percentile values were examined by KDOQI-recommended ferritin (≥100 ng/ml) and TSAT (≥20 %) thresholds. Regression tree methods were used to identify iron status markers and clinical characteristics most associated with lower HGB percentiles.
The cohort was 62 % male, 23 % African American, and 12 % Hispanic, median age 12 years, and median HGB 12.9 g/dl. 34 % had low TSAT and 93 % low ferritin as defined by KDOQI. Distribution of HGB percentile values was lower in those with ferritin ≥100 ng/ml, while TSAT ≥20 % was associated with only modest increase in HGB percentile. In regression tree analysis, lower glomerular filtration rate (GFR), serum iron <50 μg/dl and ferritin ≥100 ng/ml were most strongly associated with lower HGB percentile.
The level of GFR was significantly associated with HGB. Higher serum ferritin was associated with lower HGB in this cohort. Low serum iron in the context of normal/increased ferritin and low HGB may be a useful indicator of iron-restricted erythropoiesis.
KeywordsChronic kidney disease Hemoglobin Iron deficiency Anemia
At the Johns Hopkins University School of Medicine, Dr. Atkinson was supported by Grant Number UL1 RR 025005 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NCRR or NIH.
The CKiD prospective cohort study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, with additional funding from the National Institute of Neurologic Disorders and Stroke; the National Institute of Child Health and Human Development; and the National Heart, Lung, and Blood Institute. The CKiD prospective cohort study has clinical coordinating centers (principal investigators) at Children’s Mercy Hospital and the University of Missouri-Kansas City (Bradley Warady, MD) and Children’s Hospital of Philadelphia and the University of Pennsylvania (Susan Furth, MD, PhD), a Central Biochemistry Laboratory at the University of Rochester (George Schwartz, MD), and a data coordinating center at the Johns Hopkins Bloomberg School of Public Health (Alvaro Muñoz, PhD) (U01-DK-66143, U01-DK-66174, U01-DK-082194, and U01-DK-66116). Meredith Atkinson MD, MHS was supported by the National Institute of Diabetes and Digestive and Kidney Diseases (K23-DK-084116).
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