Erythrocyte filterability and heme catabolism during the menstrual cycle.

Erythrocyte filterability, reticulocyte count, total serum bilirubin, and CO hemoglobin percent saturation (COHb) were measured throughout one menstrual cycle in 17 women. The filterability was significantly depressed during the progesterone phase compared with the estrogen phase. The depressed filterability was accompanied by significant increases in reticulocyte count, total serum bilirubin, and COHb. Significant correlations were seen between filterability, reticulocyte count, and total serum bilirubin. However, COHb did not correlate significantly with any of the other variables studied. This is probably due to increased ventilation during the progesterone phase balancing the increased endogenous production of CO. It is possible that cyclic variations in heme turnover are related to changes in erythrocyte characteristics during the progesterone phase.