Sex and Age Differences in Serum Potassium in The

midstream urine samples. Epithelial cell and erythrocyte counts in midstream urine specimens changed significantly during the menstrual cycle (Fig. 1). Epithelial cell counts during the luteal phase were higher than those during the other three phases in midstream urine. Erythrocyte counts during the menstrual phase were higher than those during the other three phases. Other cell counts did not vary significantly with the menstrual cycle. The values at the 90th percentiles of the results for the midstream urine samples during the menstrual, follicular, ovulatory, and luteal phases, respectively, were as follows: