Laboratory blood test results beyond normal ranges could not be attributed to healthy aging

Aging is related to a decline in the function of many organs. The results of blood tests are essential for clinical management and could change over a lifespan reflecting aging. The aim of this study was to examine serum levels of liver, kidney, and bone marrow function and to study their dynamics as a function of age and sex. The cross-sectional study conducted in Poland included 180 healthy individuals (20–90 years) divided into subgroups by sex and decade. These included subgroups of ≥65 or <65 years (men and women). We investigated serum levels of creatinine, estimated glomerular filtration rate, estimated effective renal blood/plasma flow, urine pH, urine neutrophil gelatinase-associated lipocalin (NGAL) as well as serum levels of transaminases, bilirubin, total cholesterol (TC), international normalized ratio (INR), and blood morphology. All parameters were within normal range in all groups. Urine NGAL was higher in men aged ≥65 years than women (25.67 ± 53.65 vs 16.49 ± 34.66, P = .001); serum levels of TC and platelet (PLT) count were higher in women than men aged ≥65 years (221.0 ± 41.7 vs 188.4 ± 48.2 and 250.3 ± 47.8 vs 202.5 ± 57.9, P = .003 and P = .038, respectively). The INR was lower in women (0.97 ± .06 vs 1.19 ± 0.48, P = .03). These blood tests were normal in healthy people aged ≥65 years. Higher PLT and TC and lower INR in women might indicate a higher risk of cardiovascular diseases. These changes in blood tests were not attributed to aging itself.