A rapid fluorometric enzyme immunoassay for the determination of neonatal TSH from blood spots.
We describe a novel method for the detection of thyrotropin from dried blood spots using a horseradish peroxidase-labelled sandwich enzyme immunoassay with fluorometric detection. The detection limit of the present assay is 1.25 mIU/l with within-run and between-run imprecision being in the range 5.2 to 11.4%. The results of the assay correlate well with two commercial methods: an enzyme immunoassay (r = 0.93) and a time-resolved fluorescence assay (r = 0.90). The blood spot values also show a good correlation (r = 0.93) with respective values obtained from plasma using a commercial immunoradiometric method. The assay may also be performed colorimetrically with sensitivity similar to the fluorometric assay. However, the latter provides a wider dynamic range with an upper limit of 400 mIU/l while the colorimetric method reaches a plateau at 25 mIU/l. Due to its simplicity and rapid performance (3 h), the fluorometric assay is suitable for the routine screening of congenital hypothyroidism.
Tuuminen
T
T
Labsystems Oy, Helsinki, Finland.
Rakkolainen
A E
AE
Welin
M G
MG
Weber
T H
TH
Nylander
P L
PL
Käpyaho
K I
KI
D000906:Antibodies; D001800:Blood Specimen Collection / Q000379:methods; D003124:Colorimetry / Q000379:methods; D003409:Congenital Hypothyroidism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis*; D007124:Immunoenzyme Techniques; D007231:Infant, Newborn; D008856:Microscopy, Fluorescence / Q000379:methods; D011863:Radioimmunoassay / Q000379:methods; D013972:Thyrotropin / Q000097:blood*
D000906:Antibodies; D013972:Thyrotropin