Changes in electrolytes, urea and creatinine excretion during dry and wet seasons.

Twenty-four-hour urine samples were collected from 179 male and female medical students in Ibadan, and 112 medical students in Zaria. The values for 24-h urine volume, urinary electrolytes, urea and creatinine exhibited a skewed distribution and were normalized by logarithmic transformation. The geometric means values for the 24-h urine volume for the dry season were significantly less than those for the wet season in Ibadan and Zaria. The mean urinary electrolytes, urea, and creatinine levels were significantly less during the dry season than during the wet season at Ibadan. In the Zaria subjects the changes in these urinary constituents during the dry and wet seasons were the reverse of those at Ibadan. These results could explain the absence of significant seasonal changes in urinary specific gravity and the low occurrence of urinary calculi in the southern part of Nigeria.