Thyroid function tests ppt

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Thyroid function tests ppt

  1. 1. Dr. Vijay Marakala, MBBS, MD. Senior Lecturer BIOCHEMISTRY IMS, MSU.
  2. 2. Introduction Indications Assay of Hormones Radio Iodine Uptake Detection of Thyroid Antibodies
  3. 3. THE THYROID GLAND IS A BUTTERFLY- SHAPED ENDOCRINE GLAND THAT IS NORMALLY LOCATED IN THE LOWER FRONT OF THE NECK
  4. 4. Laboratory determinations of thyroid function are useful in distinguishing patients with euthyroidism (normal thyroid gland function) from those with hyperthyroidism (increased function) or hypothyroidism (decreased function)
  5. 5. Hypothyroidism Hyperthyroidism
  6. 6. Cold intolerance, Bradycardia Depression Fatigue, Goiter Hyperlipidemia Weight gain Dry skin and dry hair, Myxedema Menstrual irregularities
  7. 7. Heat intolerance Fine resting tremor Tachycardia Palpitations Anxiety Sleep disturbance Irritability Fatigue Menstrual irregularities
  8. 8. Suspicion of thyroid disease based on clinical signs and symptoms Screening for thyroid disease Evaluation of treatment for thyroid disease.
  9. 9. Thyroid-stimulating hormoneTSH Serum total thyroxineT4 Serum total triiodothyronineT3 Free thyroxineFT4 Free T3FT3 Antithyroid peroxidase antibodies, Antithyroglobulin antibodiesThyroid antibodies
  10. 10. Elevated TSH (>5 mU/L hypothyroidism Low TSH (<0.5 mU/L hyperthyroidism Normal range: 0.5 – 5mU/L One of the best thyroid function screening test
  11. 11. Hypothyroidism • Decreased T4 Hyperthyroidism • Increased T4 Normal range: 65 – 150nmol/L
  12. 12. Hypothyroidism • Decreased T3 Hyperthyroidism • Increased T3 Normal range: 1.8 – 3nmol/L
  13. 13. 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
  14. 14. In nonthyroidal illness, a low FT3 level is a nonspecific finding. FT3 is done to rule out T3 toxicosis Normal Adults: 4.0–7.4 pmol/L
  15. 15. The free thyroxine index (FTI) is a mathematical calculation used to correct the estimated total T 4 for the amount of TBG present. Make a calculation based on results of T 3 uptake and T 4 total, as follows: FTI= Total T4XT3 UPTAKE(%)/100 Normal Adults: 1.5–4.5 index
  16. 16. • RadioimmunoassayRIA • Enzyme-linked immunosorbant assayELISA • Chemiluminescent immunoassayCLIA • Fluorescent immunoassayFIA
  17. 17. Antithyroid peroxidase antibodies Used to diagnose suspected Hashimoto’s thyroiditis in hypothyroidism Antithyroglobulin antibodies Used to diagnose autoimmune thyroiditis or Graves’ disease in hyperthyroidism
  18. 18. TRH administration stimulate production of TSH If hypothalamo-pituitary-thyroid axis is normal, T3 and T4 secretions will be increased
  19. 19. In primary hyperthyroidism • little or no change in TSH levels In primary hypothyroidism • Prompt increase in TSH In secondary hypothyroidism • Does not produce an increase in TSH
  20. 20. 131I used to detect functional derangements of thyroid gland. About 15 mci of 131I given intravenously After a few hours, the patient is monitored at the neck region by movable gamma-ray counter, which will pick up the radiation emitted by thyroid gland
  21. 21. Normal response • About 25% uptake by thyroid within 2 hours • About 50% uptake by thyroid within 24 hours Abnormal response • Increased uptake in hyperthyroidism • Decreased uptake in hyporthyroidism

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