Performance Data - Siemens IMMULITE 2000 Manual Del Usario

Based on the studies of healthy subjects,
the IMMULITE 2000 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 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
thyroglobulin 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
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thyroglobulin level.
IMMULITE 2000 Thyroglobulin (PIL2KTY-22, 2015-04-22)
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.
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
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anomalous result. These reagents have
been formulated to minimize the risk of
interference; however, potential
interactions between rare sera and test
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components can occur. For diagnostic
purposes, the results obtained from this
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Some
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 ng/mL.
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I Conversion Factor:
ng/mL  1.515  pmol/L
(CRM 457; Molecular mass 660 kDa)
Calibration Range: Up to 300 ng/mL
(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
(0.3 pmol/L)
Functional Sensitivity: 0.9 ng/mL
(1.4 pmol/L)
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