Correlation of urine and plasma cytokine levels among reproductive-aged women.

ABSTRACT

BACKGROUND: Inflammation is implicated in many adverse health conditions, and recent interest has focused on the effects of chronic low-grade inflammation in generally healthy populations. Cytokines measured in plasma or serum are commonly used as biomarkers of systemic levels of inflammation. Measurement of cytokines in urine may offer a simpler and less invasive alternative, although the degree to which levels of cytokines correlate in plasma and urine among healthy individuals is unknown. MATERIALS AND METHODS: We assessed the correlation of blood and urine levels of 13 cytokines, including interleukin (IL)-1b, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12(p70) and IL-13, granulocyte macrophage colony-stimulating factor, interferon gamma and tumour necrosis factor alpha in 61 healthy women aged 18-30. Cytokine concentrations were considered with and without correction for creatinine. RESULTS: Plasma and urine levels of the 13 cytokines were not significantly correlated using measured urinary cytokine concentrations and after adjustment for creatinine. Correlation coefficients for log-transformed cytokine concentrations in paired plasma and urine specimens ranged from -0.28 to 0.087. CONCLUSIONS: These results suggest that urine has limited utility as a proxy for plasma for the measurement of inflammatory factors in a healthy population with low levels of inflammation.