Estimation of erythropoietin secretion rate in normal and uremic subjects
Coles, G.A.; Liberek, T.; Davies, M.E.; Robinson, M.; Jones, J.; Thomas, G.; Davies, M.; MacDougall, I.C.; Williams, J.D.
American Journal of Physiology 263(5 Pt 2): F939-F944
1992
ISSN/ISBN: 0002-9513 PMID: 1443181 Document Number: 396282
We have developed a method for directly estimating the secretion rate of endogenous erythropoietin (EPO) in human subjects. Carrier-free recombinant human EPO was labelled with 125I by the chloramine T method. Human serum albumin was then added prior to removal of free iodide. Seven normal subjects and nine patients with chronic uremia and anemia were studied. Each subject received a bolus of 125I-EPO according to body size and then a constant infusion for 5 h. Secretion rate was calculated as the rate of infusion divided by serum EPO specific activity given by the protein-bound counts divided by the EPO concentration. Serum EPO concentration was significantly higher in the patients than the controls (mean 30.9 pg/ml vs. 11.1 pg/ml, P lt 0.05), although all values were within the normal range. Mean EPO secretion rate was 255 in the patients (range 68-1,101) and 190 pg cntdot kg-1 cntdot h-1 in the normal group (range 52-382). This difference was not significant. As the subjects were in a steady state, EPO disappearance/degradation was the same in patients compared with controls despite a relatively hypoplastic marrow.