Thyroid function tests measure levels of thyroid hormones and thyroid stimulating hormone (TSH) to determine if the thyroid gland is functioning normally (euthyroidism) or abnormally (hyperthyroidism or hypothyroidism). The main tests are TSH, T4, and sometimes T3, which measure total or free (unbound) levels of these hormones. Abnormal results can indicate under- or overactive thyroid function. Thyroid antibodies may also be measured to help diagnose autoimmune thyroid disorders. Thyroid function tests are recommended for patients with neck swelling, irregular heartbeat, fertility issues or family history of thyroid problems.

1. THYROID FUNCTION TESTS
CLINICAL PHARMACY
By- Ranjeet Kumar
(Pharmacy Practice)

2. THYROID FUNCTION
TESTS

3. THYROID GLAND

4. FUNCTIONS OF THYROID GLAND
Secretion of hormones i.e.
T3 and T4
Plays major role in growth ,
metabolism & development
of human body

5. WHY THYROID FUNCTION TESTS ?
To determine and distinguish patients with Euthyroidism
i.e.( normal thyroid gland function ) from those with
Hyperthyroidism (increased function) or
Hypothyroidism (decreased function )

6. THYROID FUNCTION TESTS
• The usual blood tests done for thyroid function are TSH, T4 and
sometimes T3.
• A blood sample is taken from a vein in the arm & sent off to the
lab for analysis .
• Usually the free or active portion of T4 & T3 is measured.
• Typical reference ranges for healthy adults are :
• In pregnancy the serum TSH reference range is different.
TEST FROM TO UNITS
TSH 0.4 4.0 mU/L
FT4 9.0 25.0 pmol/L
FT3 3.5 7.8 pmol/L

8. TSH Thyroid – stimulating hormone
T4 Serum total thyroxine
T3 Serum total triiodothyronine
FT4 Free thyroxine
FT3 Free T3
THYROID
ANTIBODIES
Antithyroid peroxidase antibodies ,
Antithyroglobulin antibodies

9. TSH : THYROID STIMULATING HORMONE
• Elevated TSH
>5mU/LHYPOTHYROIDISM
• Low TSH < 0.5
mU/LHYPERTHYROIDISM

10. T4 : SERUM TOTAL THYROXINE
NORMAL : 65-150nmol/L
HYPOTHYROIDISM
Decreased T4
HYPERTHYROIDISM
Increased T4

11. T3 : SERUM TOTAL TRIIODOTHYRONINE
NORMAL : 1.8-3nmol/L
HYPOTHYROIDISM
Decreased T3
HYPERTHYROIDISM
Increased T3

12. FT4: FREE THYROXINE
•Is the metabolically active thyroid hormone
– not bound to protein .
•Should be ordered when TSH is abnormal to
determine thyroid hyperfunction or
hypofunction
•Normal range : 10-23 pmol/L

13. FREE THYROXINE INDEX (FTI)
• The free thyroxine index (FTI) is a mathematical
calculation used to correct the estimated total T4 for
the amount of TBG present.
• A calculation is made based on results of T3 Uptake
and T4 total as Follows :
• FTI = Total T4* T3 uptake (%)/100
• Normal adults : 1.5- 4.5 index

14. RADIOACTIVE IODINE UPTAKE
131I used to detect functional derangements of thyroid
gland.
About 15mci of radioactive iodine is given i.v.
After a few hrs. , the patient is monitored at the neck
region by movable gamma-ray counter , which will pick
up the radiation emitted by thyroid gland.

15. RESPONSE
NORMAL
RESPONSE
• About 25% uptake by
thyroid within 2 hrs.
• About 50% uptake by
thyroid within 24 hrs.
ABNORMAL
RESPONSE
• Increased uptake in
hyperthyroidism
• Decreased uptake in
hypothyroidism.

16. THYROID ANTIBODIES
Antithyroid Peroxidase
Antibodies
Used to diagnose suspected
Hashimoto’s thyroiditis in
hypothyroidism
Antithyroglobulin
antibodies
Used to diagnose autoimmune
thyroiditis or Grave’s disease in
hyperthyroidism

17. WHEN TO HAVE THYROID FUNCTION TEST ?
• Swelling or thickening in the neck.
• An irregular or fast heart rate.
• High cholesterol
• Osteoporosis
• Fertility problems, abnormal menstrual cycle ,recurrent
miscarriage.
• Family history of autoimmune disorders.
• Feeling unwell after having a baby.
• Symptoms of an over- or under active thyroid.e.t.c

18. WHAT CAN AFFECT THE RESULTS OF TFTs ?
• Thyroid function tests can be influenced by :
• Any serious illness such as heart attack, infection ,
trauma, serious liver or kidney diseases etc..
• Any other medication used to treat thyroid disorders ,
especially when taking too much or little.
• Any other medication including contraceptive pills,
steroid hormones, NSAIDs, Lithium, amiodarone etc..

20. THANK YOU