Siemens Coat-A-Count TSH IRMA Manual Del Usuario página 8

IRMA procedure. The table shows that
Coat-A-Count TSH IRMA results are
essentially unaffected by wide variations in
the concentration of the compounds
tested. (See "Specificity" table.)
Linearity: Samples were assayed under
various dilutions. (See "Linearity" table for
representative data.)
Recovery: Samples spiked 1 to 19 with
four TSH solutions (23, 139, 274 and
810 µIU/mL) were all assayed. (See
"Recovery" table for representative data.)
Bilirubin: Presence of bilirubin in
concentrations up to 200 mg/L has no
effect on results, within the precision of the
assay.
Hemolysis: Presence of packed red blood
cells in concentrations up to 30 µL/mL has
no effect on results, within the precision of
the assay.
Alternate Sample Type: To assess the
effect of alternate sample types, blood
was collected from 48 volunteers into
plain, heparinized, EDTA and Becton
®
Dickinson SST vacutainer tubes. All
samples were assayed by the Coat-A-
Count TSH IRMA procedure, with the
following results.
(Heparin) = 1.03 (Serum) – 0.04 µIU/mL
r = 0.985
(EDTA) = 0.99 (Serum) + 0.02 µIU/mL
r = 0.986
(SST) = 1.01 (Plain Tubes) – 0.02 µIU/mL
r = 0.989
Means:
2.10 µIU/mL (Serum)
2.13 µIU/mL (Heparin)
2.11 µIU/mL (EDTA)
2.11 µIU/mL (SST)
Protein Effect: To simulate various
protein concentrations, experiments were
performed in which 6.0 mL aliquots of
three serum pools were freeze-dried and
then reconstituted with various volumes of
water (4.0, 6.0 and 9.0 mL). Each
reconstituted aliquot was then assayed by
the Coat-A-Count TSH IRMA procedure.
Observed and expected TSH values are
tabulated in µIU/mL. (The factor to correct
for reconstitution volume is tabulated
below) The results indicate that variations
in protein have no clinically significant
effect on the Coat-A-Count TSH IRMA
assay. (See "Protein Effect" table.)
8
Method Comparison: Coat-A-Count TSH
IRMA procedure was compared to
IMMULITE Third Generation TSH assay
on 107 patient samples, with TSH values
ranging from approximately 0.29 to
19.3 µIU/mL. (See "Method Comparison"
graph.) By linear regression:
(CAC IRMA) = 1.05 (IMMULITE) – 0.13 µIU/mL
r = 0.998
Means:
2.83 µIU/mL (Coat-A-Count IRMA)
2.81 µIU/mL (IMMULITE)
References
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The use and misuse of the sensitive thyrotropin
Coat-A-Count TSH IRMA (PIIKTS-8, 2010-11-04)