Estimation of erythropoietin secretion rate in normal and uremic subjects.
We have developed a method for directly estimating the secretion rate of endogenous erythropoietin (EPO) in human subjects. Carrier-free recombinant human EPO was labeled 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 < 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.kg-1 x 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.
Coles
G A
GA
Institute of Nephrology, University of Wales College of Medicine, Cardiff, United Kingdom.
Liberek
T
T
Davies
M E
ME
Robinson
M
M
Jones
J
J
Thomas
G
G
Davies
M
M
MacDougall
I C
IC
Williams
J D
JD
D000328:Adult; D000740:Anemia / Q000097:blood / Q000378:metabolism; D002908:Chronic Disease; D004921:Erythropoietin / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012016:Reference Values; D014511:Uremia / Q000097:blood / Q000378:metabolism*
D004921:Erythropoietin