ORIGINALARTICLE : A mild decrease of renal function is related to increased hemoglobin level during 5-year follow-up period

Background/Aims: We analyzed chronological changes in hemoglobin accordingto renal function changes over a 5-year follow-up period. Methods: We enrolled 5,266 adults with a glomerular filtration rate (GFR) ≥ 60mL/min/1.73 m2 at an initial examination at a routine health check-up; a follow-up examination was conducted 5 years later. We categorized the subjects accordingto GFR ratio (groups 1, 2, and 3, defined as GFRratio ≥ 1.00, 0.75 to 0.99,and < 0.75, respectively). Results: The mean hemoglobin level in subjects with a GFR of 60 to 74 was higherthan in those with a GFR of 75 to 89 or ≥ 90 mL/min/1.73 m2 at the initial examination(all p < 0.001). Among females and males, the frequencies of increasedhemoglobin were 46.8% and 40.6% in the GFRratio group 1, 52.4% and 46.1% ingroup 2, and 59.6% and 52.5% in group 3 over the 5-year period, respectively (allp < 0.001). With multiple logistic regression, group 3 showed 1.594-fold (95% confidenceinterval [CI], 1.127 to 2.225) and 1.353-fold (95% CI, 1.000 to 1.830) higherlikelihoods of increased hemoglobin over the 5-year follow-up period in femalesand males, respectively. The estimated difference in hemoglobin level was highestin group 3 in both genders. These findings were more evident in subgroupswithout metabolic syndrome, diabetes mellitus, hypertension, or GFR less than90 mL/min/1.73 m2. Conclusions: Among a population with GFR ≥ 60 mL/min/1.73 m2, a mild decreasein GFR over a 5-year follow-up period was associated with an increase inhemoglobin levels.