1. Endogenous response to a two-unit phlebotomy within a 24-h period in normal individuals.
Endogenous response to a two-unit phlebotomy within a 24-h period in normal individuals. All data were collected after completion of the second phlebotomy (time zero). Hb decreases from a normal value of 15 to 12 g/dl by the end of day 1. Endogenous erythropoietin (EPO) increases from normal levels of approximately 15 to 200 mU/ml. This increase in EPO levels leads to a progressive increase in the Hb such that during the first 2 wk, approximately half of the original deficit (one unit) is reconstituted. The rest of the deficit would be corrected during the next 6 wk (data not shown), assuming adequate iron availability. As the deficit corrects, EPO levels decrease toward their original values. The trapezoid defines the 95% confidence limits for the data. EPO levels do not show discontinuity, and the relationship of Hb and EPO show the operation of the normal feedback process.
Steven Fishbane, and Anatole Besarab CJASN 2007;2:
©2007 by American Society of Nephrology