Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Thyroid Function Tests Orishaba Diana And Enoch T Introduction to the Thyroid Gland • Objectives • Explain the synthesis and regulation of thyroid hormone production • Describe the actions of thyroid hormones • Describe the etiology, major symptoms and pathophysiology of hyper and hypothyrodism • Understand the role of thyroid hormone measurement in the management of thyroid disease Control of thyroid hormone production Peripheral tissues Metabolic Effects of Thyroid Hormones •Effects on the function of virtually every organ system •Maintain metabolic stability and increase resting or basal metabolic rate •Increase heart rate •Increase mental alertness •Maintain GI motility & bone turnover •Brain dev’t and skeletal maturation during foetal development • Thyroid hormones regulate: - Growth and development - Temperature - Oxygen consumption - Metabolism of carbohydrate, protein and lipid - TSH secretion Thyroid disease • Can be Hypothyroidism or Hyperthyroidism. Either way, this can be a primary disease of the thyroid gland or secondary to brain lesions. • TFTs alone can differentiate the above. • Other Ix are important for specific causes eg • • • • Anti-thyroid antibodies (Anti-peroxidase) –in hashimoto’s thyroiditis, titre tells likelihood of progression to overt hypothyroidism. TSH receptor antibodies – Grave’s CT scan in brain lesions Radio iodine nuclide studies etc • NB: Goitre refers to thyroid swelling and can be both in patients with hypothyroidism, euthyroidism or hyperthyroidisim. HYPOTHYROIDISM Low T3 and/or T4 Primary Causes • Autoimmune (Hashimoto’s) Thyroiditis • High amounts of Iodine eg Amiodarone • Congenital hypothyroidism • Thyroid gland agenesis/dysgenesis • Thyroiditis • Post surgery • Irradiation (Radioactive iodine, Head & Neck Ca) • Dietary Iodine deficiency • Drug effects including antithyroid medication • Infiltrations – Amyloidosis, Haemochromatosis, Fibrous Thyroiditis (Reidel’s) • Subacute (Viral), Painless (Postpartum) Thyroiditis: Transient Hypothyroidism Other Findings • • • • • • • Anaemia Hyponatremia Elevated triglycerides & Cholesterol Sinus bradycardia Pericardial effusion ECG: Low voltage Slow relaxation of deep tendon reflexes Diagnosing Hypothyroidism Insidious onset, so recognition is sometimes difficult. Always remember the Negative Feedback Loop: TSH Free T4/T3 Diagnosis ↑ ↓ Overt Primary Hypothyroidism ↑ → (usually low normal) Subclinical Primary Hypothyroidism ↓ ↓ Secondary Hypothyroidism HYPERTHYROIDISM Raised T3 and/or T4 Major Causes of Hyperthyroidism • • • • • • • • Graves disease Toxic multinodular goitre Toxic nodule Thyroiditis Excess replacement TSH secreting tumour Amiodarone Ectopic thyroid tissue • Trophoblasctic tumours Other Findings • • • • • • • Increased appetite Weight loss Resting tremor Wide pulse pressure Flow murmur Proximal muscle weakness Brisk deep tendon reflexes Diagnosing Hyperthyroidism • Try to identify the underlying cause, because treatments vary • Use Hx, physical exam, Imaging, antibody tests, etc • Always remember the negative feedback loop TSH Free T4/T3 Diagnosis ↓ ↑ Overt primary hyperthyroidism ↓ → Subclinical primary hyperthyroidism ↑ ↑ Secondary hyperthyroidism • TSH (0.3-3.5 mU/L) • Free T4 (10-25 pmol/L) • Free T3 (3.5-7.5 pmol/L) Some Questions 1. Patient comes with weight loss and palpitations. Below is his thyroid panel. What is your specific diagnosis? Patient A Clinical Biochemistry -----------------------------------------------------------------------------Sample collected : XX-Aug-XX Ref. Range Serum T.S.H. - - - - - <0.1 Free T4 - - - - - 50.2 Free T3 - - - - - 22.0 mIU/L ( 0.3 – 3.5 ) pmol/L (10.0 -25.0 ) pmol/L ( 3.5 - 7.5 ) 2. Clinical information – Cold intolerance, constipation What is your specific diagnosis? Patient A Clinical Biochemistry -----------------------------------------------------------------------------Sample collected : XX-Aug-XX Ref. Range Serum T.S.H. - - - - - 10.0 Free T4 - - - - - 13.2 Free T3 - - - - - mIU/L ( 0.3 – 3.5 ) pmol/L (10.0 -25.0 ) pmol/L ( 3.5 - 7.5 ) Hypothyroidism Treatment • Depending on the cause but usually is thyroid replacement using Levo thyroxine Hyperthyroidism Rx 1. Beta Blockers Sympathomimetic blockers Propranolol also inhibits peripheral conversion of T4 to T3 Sole Tx in transient thyrotoxicosis 2. Antithyroid drugs: Thionamides eg CARBIMAZOLE Inhibit thyroid hormone synthesis Can induce remission in Grave’s disease Control thyrotoxicosis before radioiodine or surgery In Grave’s: Keep on drugs for 1224 months, then taper to see if there’s remission S/Es: Rash, Pruritus, Arthralgias, Agranulocytosis Pregnancy: Potassium ThioUracil(PTU) Hyperthyroidism Rx 3. RadioActive Iodine 4. Surgery • Oral • Concentrates in the thyroid gland • Localised destruction • Postablative hypothyroidism • Toxic Adenoma: Lobectomy • Toxic MNG with compressive symptoms KI/Lugol’s solution • Reduces vascularity presurgery Conclusion Interpretation of TFT’s TSH T4 T3 Primary hypothyroisism High low low Secondary hypothyroidism Primary hyperthyroidism low low low Low high high high high high Secondary hyperthyroidism