Inflammatory Markers Change with Age, but do not Fall Beyond Reported Normal Ranges

We examined the serum levels of IL-6, IL-8, TNF, IL-6R, TNF-R1, and CRP and the dynamics of changes in these levels according to age. The study included healthy individuals of 20–90 years of age. Participants were divided into subgroups based on their decade of life, and into subgroups of ≥65 or <65 years. Serum cytokine levels were assayed by ELISA, and CRP using an immunoturbidimetric method. Serum CRP levels were within the normal range for all subgroups. The 60- to 70-year age group showed higher CRP than the 20- to 30- (p = 0.003), 30- to 40- (p = 0.009), and 40- to 50- (p = 0.030) year age groups. Serum cytokine levels were low. It was greater in the 60- to 70-year age group than in the 20- to 30- (p = 0.008) and 30- to 40- (p = 0.040) year groups, and was greater in the 70- to 90-year group than the 20- to 30-year group (p = 0.043). Serum TNF-R1 level in the 70- to 90-year group was greater than in all other age groups (p = 0.000 for all comparisons). Other measured parameters did not differ between groups. Serum levels of IL-6, CRP, and TNF-R1 were greater in participants ≥65 than <65 years of age. Healthy older people showed low serum levels of CRP and pro-inflammatory cytokines, but higher than in younger population. Therefore, the adjustment of normal ranges in the elderly should be considered. Serum levels of pro-inflammatory cytokines elevated beyond normal ranges indicate particular diseases.