Performance Data - Siemens IMMULITE 2000 TBG Manual Del Usuario

The TBG saturation index (TBG-SI), like
other total T4/TBG ratios, does not
necessarily convey the same information
as a free thyroxine index (FT4I).
This assay has not been validated for use
with neonates and children.
Heterophilic antibodies in human serum
can react with the immunoglobulins
included in the assay components causing
interference with in vitro immunoassays.
[See Boscato LM, Stuart MC. Heterophilic
antibodies: a problem for all
immunoassays. Clin Chem 1988:34:27-
33.] Samples from patients routinely
exposed to animals or animal serum
products can demonstrate this type of
interference potentially causing an
anomalous result. These reagents have
been formulated to minimize the risk of
interference; however, potential
interactions between rare sera and test
components can occur. For diagnostic
purposes, the results obtained from this
assay should always be used in
combination with the clinical examination,
patient medical history, and other findings.

Performance Data

See Tables and Graphs for data
representative of the assay's performance.
Results are expressed in µg/mL. (Unless
otherwise noted, all were generated on
serum samples collected in tubes without
gel barriers or clot-promoting additives.)
Conversion Factor:
µg/mL × 18.5 → nmol/L
Reportable Range: 3.5 to 80 µg/mL
(65 to 1,480 nmol/L). Standardized in
terms of WHO 1st IS 88/638.
Analytical Sensitivity: 1.6 µg/mL
(29.6 nmol/L).
Precision: Samples were assayed in
duplicate over the course of 20 days, 2
runs per day, for a total of 40 runs and 80
replicates. (See "Precision" table.)
Linearity: Samples were assayed under
various dilutions. (See "Linearity" table for
representative data.)
Recovery: Samples spiked 1 to 19 with
three TBG solutions (142, 285 and
503 µg/mL) were assayed. (See
"Recovery" table for representative data.)
Specificity: The antibody is highly specific
for TBG. (See "Specificity" table.)
IMMULITE 2000 TBG (PIL2KTB-18, 2010-07-07)
Bilirubin: Presence of bilirubin in
concentrations up to 200 mg/L has no
effect on results, within the precision of the
14
assay.
Hemolysis: Presence of hemoglobin in
concentrations up to 384 mg/dL has no
effect on results, within the precision of the
assay.
Lipemia: Presence of triglycerides in
concentrations up to 3,000 mg/dL 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 15 volunteers into
plain, heparinized, EDTA and Becton
Dickinson SST
volumes of the matched samples were
spiked with various concentrations of
TBG, to obtain values throughout the
calibration range of the assay, and then
assayed by the IMMULITE 2000 TBG
procedure.
(Heparin) = 0.97 (Serum) – 0.18 µg/mL
r = 0.994
(EDTA) = 1.00 (Serum) – 0.79 µg/mL
r = 0.994
(SST) = 0.998 (Plain Tubes) – 1.0 µg/mL
r = 0.997
Means:
26.8 µg/mL (Serum)
25.9 µg/mL (Heparin)
26.1 µg/mL (EDTA)
25.8 µg/mL (SST)
Method Comparison: The assay was
compared to IMMULITE TBG on 99
samples. (Concentration range:
approximately 3 to 55 µg/mL. See graph.)
By linear regression:
(IML 2000) = 1.03 (IML) + 0.29 µg/mL
r = 0.981
Means:
26.7 µg/mL (IMMULITE 2000)
25.6 µg/mL (IMMULITE)
References
1) Gershengorn MC, Glinoer D, Robbins J.
Transport and metabolism of thyroid hormones.
In: De Visscher M, editor. The thyroid gland.
New York: Raven Press, 1980: 81-121. 2)
Refetoff S. Thyroid hormone transport. In:
DeGroot LJ, et al., editors. Endocrinology, vol. 1.
San Francisco: Grune & Stratton, 1979: 347-56.
3) Carayon P, Castanas E, Guibout M,
Codaccioni J-L. Assessment and clinical
significance of free thyroid hormone
®
vacutainer tubes. Equal
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