3. TFT
Establish whether there
is thyroid dysfunction
➢TSH,
➢ total T4
➢total T3
To know the cause
of thyroid
dysfunction
➢Thyroid auto-antibody
➢Thyroid enzyme activities,
➢ biopsy of the thyroid
➢ultrasound
➢ isotopic thyroid scanning
4. TSH
The single most sensitive, specific & reliable test
of thyroid status.
In primary hypothyroidism = TSH is increased.
In primary hyperthyroidism= TSH is decrease
or undetectable.
5. Limitations
Tends to lag behind in thyroid hormones changes
After thyroid surgery
On thyroid replacement therapy
6. Total T4 and Total T3: Free T4 and Free T3
• More than 99% of T4 & T3 circulate
in plasma bound to protein
• Both TT4] & TT3] change if TBG alters,
e.g. in pregnancy.
• Free thyroid hormone
concentrations are independent of
changes in the concentration of
thyroid-hormone binding proteins.
• More reliable for diagnosis of
thyroid dysfunction.
7.
8. T3 hyperthyroidism
TSH suppression with T3 is ↑
&T4 normal or even
low
▪Compensatory mechanism to lack of Iodine ( T3 needs less I than T4
)
▪Due to accelerated deiodination process
9. Thyroid Antibodies & Autoantibodies
IgG Immunoglobulin ,binds at TSH receptor sites.
Measurement not essential to make a diagnosis
found in autoimmune diseases and certain malignancies
Anti-TPO ( antibodies to thyroid peroxidase / microsomal Ab)
•↑
serum titers of Abs to TPO are found in several forms of thyroidities due
to autoimmunity
• High titres,1:100 thyroglobulin & above 25units/mlTPO antibodies are
significant
10. Calcitonin in TFT
▪Diagnosis and monitoring Medullary thyroid carcinoma ( C-cell
carcinoma
▪Along with CEA ( for diagnostic sensitivity )
↑
12. US
•allows assessment of the gland and the regional lymphatics.
•presence and features of thyroid nodules can be described.
•Number, size, shape, margins, vascularity and
microcalcifications
•Non invasive & cheap but visualization behind sternum limited
13.
14. CT Vs MRI
✓CT is useful for determining the extent of airway invasion
✓MRI is superior at determining the presence of prevertebral fascia
invasion
15. PET
•limited application in thyroid disease.
•For recurrent thyroid cancer.
•This is particularly useful when the disease does not concentrate iodine, at
which point fluorodeoxyglucose (FDG) uptake increases and lesions
become positive on PET scans.
16. ISOTOPE SCANNING
•Its principal value is in the toxic patient with a nodule or nodularity of
the thyroid.
•the patient must have all normally functioning thyroid tissue ablated
