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OFT 03. TFT.pptx
- 1. By Dr. Santhosh KumarN Associate Professor Department of Biochemistry
- 2. Butterfly-shaped endocrine gland, locatedin the lower front of the neck It absorbed iodine from the circulating blood & combine with tyrosine of thyroglobulin to form TH Thyroid gland release - Thyroxine (T4) & - Tri-iodothyronine (T3)
- 3. Increased metabolic rate(Calorigenic effect) Maintenance of blood pressure Regulates enzyme activity system Heat production & Body temperature Maintain growth & development Regulates the rate of metabolisms (CH’s, Lipids & Proteins) Functions
- 4. Thyroid Function Tests(TFTs) A series of blood tests used to measure how well thyroid gland is working.
- 5. Diagnosing thyroid disorderin symptomatic person Screening newborns for hypothyroidism and adults for thyroid disorders Monitoring thyroid replacement therapy in hypo- thyroidism patients Diagnosis & monitoring female infertility patients Purpose of TFTs
- 6. Major Thyroid FunctionTests • Serum Thyroid Stimulating Hormone (TSH) • Serum free Thyroxin (T4 )& Tri-iodothyronine (T3 ) • Serum Total T4 & T3 • Radioactive iodine uptake (RAIU) test • Estimation Of Serum Cholesterol • Tests for autoimmune thyroid diseases include tests – Anti-TSH receptors antibodies – Anti-thyroglobulin antibodies – Anti-microsomal antibodies – Anti-thyroperoxidase antibodies
- 7. Serum Thyroid StimulatingHormone (TSH)Test • Sensitive, specific and reliable test of thyroid status. • Stimulation of thyroid gland by the TSH will causes the release of stored Thyroid hormones. • When T4 & T3 are too high - TSH secretion decreases • When T4 & T3 are too low, - TSH secretion increases • Useful diagnosis of primary hypothyroidism (TG failure)
- 8. Normal value :0.25 to 5.5 μIU/ml High TSH level Low TSH level Thyroid gland is failing – Primary hypothyroidism due to absence of –ve feedback control on PG - Addison’s disease, - Pituitary adenoma. Overactive thyroid gland - Primary hyperthyroidism, -Secondary hypothyroidism (Anterior pituitary failure) - Tertiary hypothyroidism (hypothalamic failure) TSH estimated by - Radioimmunoassay
- 9. Serum Free T4& T3 • Metabolically active & measures useful in condition by where TBG levels are affected. • Free TH conc. provide more reliable, of diagnosing thyroid dysfunction than measurement of total serum T4 & T3 • Normal serum Free T4 : 9.0 to 24.0 pmol/L serum Free T3 : 4.0 to 8.0 pmol/L • Elevated T4 & T3 in hyperthyroidism. Low level seen in hypothyroidism.
- 10. Serum Total T4& T3 • Total thyroid hormones includes free as well as protein bound. • levels of total thyroxin are affected by changes in levels of TBG in the absence of thyroid diseases • Normal serum total T4 : 5 to 12 μg/dL serum total T3 : 0.60 to 2.15 ng/dl
- 11. - Increased hormonesecretion is seen in states of hyperthyroidism, (raised conc. of TBG- in pregnancy & with estrogen therapy) - Decreased in serum occurs in cases of hypothyroidism, (decrease conc. of TBG- in nephrosis due to loss of TBG in urine & liver disease (decreased syn of TBG ) • T4 combined with TSH test gives the best measurement of thyroid function
- 12. Radioactive iodine uptake(RAIU) Test • It measures, how much RA-I is taken up by the thyroid gland in a certain period but does not involve imaging. • Similar test is the thyroid scan. • These two tests are commonly performed together.
- 13. Giving a radiotracer(containing radioactive iodine eg; I123 or I131) is either injected (liquid) into the body, swallowed (capsule) or inhaled as a gas. Radiotracer accumulates in the organ or area of the body being examined After 4 to 6 hours and again 24 hours. using a gamma probe to check the amount of radioactivity in the thyroid gland
- 14. It show,how much of this radioactive iodine is absorbed by the thyroid. In normal responses for 4-6 hours: 3 -16% and 24 hours: 8 -25% Higher- uptake Lower-uptake Overactive thyroid gland - Graves disease - Enlarged thyroid gland - Toxic nodular goiter - Post thyroiditis - Thyrotoxicosis Hypothyroidism Sub-acute thyroiditis Painless thyroiditis
- 15. Estimation Of CholesterolIn Serum • It is a useful index in monitoring the effectiveness of the therapy in thyroid condition. • Increased cholesterol levels seen in hypothyroidism because cholesterol carrying lipoprotein degradation is decreased
- 16. Thyroid auto-antibodies • helpsto demonstrate the presence of the auto immune disorders • Graves’ disease is associated with presence of anti-TSH-receptor Ab. • Thyroiditis is associated with the presence of anti-thyroid peroxidase Ab (anti-microsomal antibodies) • Thyroid peroxidase and thyroglobin antibodies – immunological mediated thyroid disease.
- 17. PATTERN OF DIAGNOSISFOR THYROID DISORDERS
- 18. CLINICAL SIGNIFICANCE OFTHYROID HORMONES Hypothyroidism Hyperthyroidism Primary Secondary Tertiary Causes: - Iodine deficiency, Excess iodine intake & thyroiditis -Hypopituitarism – adenoma, Destruction of pituitary -- Hypothalamic dysfunction Causes: - Grave’s disease - Multi-nodular goiter - Thyroid destruction - Metastatic thyroid carcinoma Symptoms: - Weight gain, Lack of energy, Confusion, Symptoms: Weight loss, Fatigue,
- 19. Case report -01 Following is the laboratory report of a patient Report Normal Ranges Serum T3 : 250 ng/dl (120 to 190 ng/dl) Serum T4 : 20 μg/dl (5 to 12 μg/dl) Serum TSH : 0.01 μU/ml (0.5 to 5.0 μU/ml) Q: a) What is the probable diagnosis? b) What are clinical features associated with this condition? c) What are the other investigations suggested for this patient?
- 20. a) What isthe probable diagnosis? Hyperthyroidism (Over activity of thyroid gland) b) What are clinical features associated with this condition? • Causes: Grave’s disease, Multi-nodular goiter and Metastatic thyroid carcinoma • Symptoms: elevated BMR, tachycardia, Weight loss, Fatigue, sleeplessness Nervousness, Heat intolerance, excessive sweating, muscle weakness &Tremors c) What are the other investigations suggested for this patient? • Basal metabolic rate (BMR), • Serum cholesterol and • Radioiodine uptake test & Thyroid scan help to determine why thyroid is overactive: • Detection of auto-antibodies (thyroid stimulating IgS or long acting thyroid stimulators(LATS)
- 21. Case report –02 Following is the laboratory report of a patient Report Normal Ranges Serum T3 : 90 ng/dl (120 to 190 ng/dl) Serum T4 : 2.5 μg/dl (5 to 12 μg/dl) Serum TSH : 20 μU/ml (0.5 to 5.0 μU/ml) Serum Cholesterol: 300 mg/dl (150-200 mg/dl) Q: a) What is the probable diagnosis? b) What are clinical features associated with this condition ? c) What dietary advice should be given to the patient d) Why does hypothyroidism cause hypercholesterolemia in the above condition
- 22. a) What isthe probable diagnosis? Hypothyroidism b) What are clinical features associated with this condition ? Causes: Primary - Iodine deficiency, Excess iodine intake & thyroiditis Secondary: Hypopituitarism – adenoma, destruction of pituitary Tertiary- Hypothalamic dysfunction Symptoms: Tiredness, Weight gain, intolerance of cold conditions, hoarseness of voice, hair loss, constipation, depression, bradycardia, dry skin. puffy face & Low motor activity. Cretinism (Neonatal hypothyroidism)– multiple congenital defects & mental retardation . Myxoedema (In adults) with puffiness of the face, bagginess under eyes, slowness in physical activities and overall weight gain
- 23. c) What dietaryadvice should be given to the patient Consumption of iodized salt and to avoid goitrogenic foods eg. Cabbage and cauliflower d)Why does hypothyroidism cause hypercholesterolemia in the above condition - Low thyroid hormones, cannot process as much of cholesterol in the liver . - Body removes less LDL cholesterol from the blood lead to high levels of LDL and total cholesterol.
- 24. Have a greatday to all Thank you Next : AFTs