Performance Data - Siemens IMMULITE 1000 Thyroglobulin Manual Del Usuario

Based on the studies of healthy subjects,
the IMMULITE Thyroglobulin's cutoff was
determined to be 55 ng/mL. Specimens
with thyroglobulin levels greater than
55 ng/mL are considered elevated and
require further testing regarding the
thyroid status of the patient.
Consider these limits as guidelines only.
Each laboratory should establish its own
reference ranges.
Limitations
Because thyroglobulin autoantibodies
(TgAb) can interfere with both competitive
immunoassays and immunometric assays
for thyroglobulin, all patients should be
screened for TgAb by a sensitive
immunoassay: recovery studies are not
adequate for ruling out interference by
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TgAb. If the laboratory chooses to
report thyroglobulin results in
TgAb-positive sera, each report should
include a warning to the physician to
interpret the thyroglobulin result with
caution, as the presence of TgAb may
cause underestimation of the thyroglobulin
level as measured by immunometric
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assays. Thyroglobulin antibodies (TgAb)
are present in the majority of patients with
Hashimoto's thyroiditis, but also in
approximately 5% of healthy individuals.
At least 6 weeks should elapse after
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thyroidectomy or I treatment.
reports have indicated that thyroglobulin
levels may remain elevated for several
months following successful treatment. In
this case, serial determinations assessed
relative to a post-treatment baseline
established for the patient may still be of
value in monitoring.
It is important to obtain thyroglobulin
measurements before administering
for scanning, since the scan may result in
the release of large amounts of thyro-
globulin from even a very small number of
cells. Likewise, samples for thyroglobulin
assay should not be collected prematurely
following procedures such as needle
biopsy that are likely to cause a transient
elevation in the thyroglobulin level.
Although thyroglobulin measurements are
of established value in the differential
diagnosis of congenital hypothyroidism,
they are not recommended for use in
screening for this condition since a wide
spectrum of thyroglobulin levels are
obtained for this condition.
IMMULITE/IMMULITE 1000 Thyroglobulin (PILKTY-24, 2015-04-30)
EDTA plasma has an effect on the
measurement of thyroglobulin in the
procedure.
Immunologically inactive thyroglobulin
may not be determined by this assay.
In patients receiving thyroid suppression
therapy, thyroglobulin may not be reliably
detected.
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.
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Performance Data

See Tables and Graphs for data
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Some representative of the assay's performance.
Results are expressed in ng/mL. (Unless
otherwise noted, all were generated on
serum samples collected in tubes without
gel barriers or clot-promoting additives.)
Conversion Factor:
ng/mL  1.515  pmol/L
(CRM 457; Molecular mass 660 kDa)
Calibration Range: Up to 300 ng/mL
131
I
(455 pmol/L)
Standardized against Certified Reference
Material for human thyroglobulin
(CRM 457) in terms of the Community
Bureau of Reference of the European
Commission.
Analytical Sensitivity: 0.2 ng/mL
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(0.3 pmol/L)
Functional Sensitivity: 0.9 ng/mL
(1.4 pmol/L)
High-dose Hook Effect:
None up to 50,000 ng/mL.
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