|
The accuracy of an in-house test
The measurement of total thyroxine (T4) concentrations has
become a widely accepted screening tool for the analysis of thyroid
function in veterinary medicine. SNAP®
T4 Tests allow you to measure T4 concentrations
in your in-house laboratory, providing the convenience of timely
results and the ability to modify medications or diagnostic options
while your client is still in the clinic.
 Correlation of the IDEXX SNAP T4 Test
with radioimmunoassay*
Each SNAP T4 lot is tested with canine and feline serum
from both healthy animals and those with thyroid disease. The IDEXX
internal calibration process ensures that each lot of T4
maintains a high level of performance and will provide accurate
results for patient samples across all areas of the range.
Canine Hypothyroidism—A T4
value within the reference range (1.3–2.9 g/dL) indicates that
hypothyroidism is unlikely. However, a low T4 value is not
definitively diagnostic for hypothyroidism because outside factors
(e.g., nonthyroidal illness and some drugs) can falsely lower T4
levels. A low total T4 is only a piece of the puzzle in
diagnosing the disease. Other information to take into consideration
includes clinical signs, a biochemical profile (hypercholesterolemia)
and a hematology analysis (a nonregenerative anemia). However, when
the above analysis is inconclusive, experts recommend that the T4
test be repeated in four weeks. If still inconclusive, additional
thyroid diagnostics (TSH or free T4 by equilibrium
dialysis) may be needed.
Feline hyperthyroidism—Experts
agree that a diagnosis can be made from a single high T4
result. Because euthyroid sick patients have suppressed T4
and T3 concentrations, concomitant hyperthyroidism should
be considered in any middle- to old-aged cat with a nonthyroidal
illness and a high-normal T4 level, especially if clinical
signs are present.
|
The data presented show excellent clinical agreement between
serum T4 concentrations measured by the SNAP T4
Test and radioimmunoassay (RIA). The correlation coefficient (r) is
a measure of how well a linear equation depicts the relationship
between two variables. An r-value of 0.92 indicates excellent
overall agreement between T4 concentrations measured by
the SNAP test and T4 concentrations measured by RIA.
|
|
How
will the SNAP
