Free cortisol/cortisone ratio in morning urine as a biomarker of health status in older Japanese adults

Abstract Secretion of cortisol in humans peaks in the morning, reflecting robust circadian rhythms, which are essential for homeostasis. To examine the hypothesis that free cortisol levels in the morning can predict general health status, free cortisol and cortisone in urine samples collected from 7813 Japanese older adults upon waking were measured by liquid chromatography-mass spectrometry (LCMS). The ratio of cortisol to cortisone in 5298 urine collected between 6 and 11 AM showed consistent correlations with favorable personal attributes linking to good health. The odds ratio of poor health, as defined by multiple clinical criteria (BMI ≥25, SBP ≥140 mmHg, C-reactive protein ≥0.5 mg/dL, and HbA1c ≥5.6%) or cardio-cerebro-vascular disease history, robustly showed negative associations with the cortisol/cortisone ratio. The free cortisol/cortisone ratio in urine samples collected upon waking is a promising biomarker of good health and might be applicable to a wide range of research and medical settings.