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Does sampling site influence levels of free thyroxine and thyrotropin determined by a current immunoassay?
Jan M M Rondeel1, Jaldira S Albers, Eelco J Schroor
1Isala Klinieken, Department of Clinical Chemistry, P.O. Box 10400, 8000 GK Zwolle, The Netherlands. j.rondeel@isala.nl
Objectives:
To examine the effect of sampling site on levels of free thyroxine (fT4) and thyrotropin (TSH).
Design And Methods:
fT4 and TSH were determined by a current immuno-assay in paired samples of capillary and venous blood drawn from 30 euthyroid adults.
Results:
Mean levels of fT4 and TSH did not differ significantly between capillary and venous blood; capillary and venous levels correlated well and did not differ significantly from unity.
Conclusions:
Sampling site does not influence levels of fT4 and TSH.
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