RESUMEN
The circadian rhythm of uric acid concentration was studied under near-normal tropical conditions in 162 healthy volunteers (103 males and 59 females; 7 to 75 year). They were mostly medical students, staff members and members of their families. They were classified into 4 age groups: A (7-20 y; N = 42), B (21-40 y; N = 60), C (41-60 y; N = 35) and D (61-75 y; N = 25). They followed a diurnal activity from about 06:00 to about 22:00 and nocturnal rest. Blood samples were collected from each subject every 6 for 24 h (4 samples). Serum uric acid was measured spectrophotometrically. Data from each subject were analyzed by cosinor rhythmometry. Effects of gender, age, diet (vegetarian vs. omnivore), and smoking status on the rhythm-adjusted mean (MESOR) and circadian amplitude were examined by multiple-analysis of variance. A marked circadian variation was found in uric acid concentration in healthy Indians of all age groups. Furthermore, both the MESOR and circadian amplitude underwent changes with advancing age. In addition to effects of gender and age, diet and smoking were also found to affect the MESOR of circulating uric acid concentration in healthy Indians residing in northern India. The present observations confirmed a definite rhythm in uric acid concentrations with significant effect of gender, age, diet, and smoking status on uric acid concentration in clinical health. Mapping the circadian rhythm of serum uric acid is needed to explore their role in different pathophysiological conditions.