1. www.drsarma.in 1 Thyroid Function Tests 1.TSH (normal range 0.3- 4.0 mU/L) 2.Free T4 (normal range 0.7- 2.1 ng/dL) 3.Free T3 (normal range 1.4 - 4.4 pg/dL) 4.Anti-Thyroid Antibodies (TPO Ab, TSI) 5.Nuclear Scintigraphy ( I 123 or TC 99m ) 6.FNAC of nodule

2. www.drsarma.in 2 What tests should I order ? As per the Guidelines of the AACE and ATA, ITS 1. TSH alone if Hypothyroidism is suspected 2. TSH and Free T 4 only if Hyperthyroidism is suspected or for routine evaluation 3. Free T 3 if T 3 toxicosis is suspected 4. For follow-up of treatment only TSH 5.Don’t order for Total T 4 or Total T 3 6.Never order RIU in pregnancy or lactation

3. www.drsarma.in 3 LOW NORMAL HIGH FREE THYROXINE or FT4 EUTHYROID SUB-CLINICAL HYPERTHYROID NON THYROID ILLNESS - NTI NTI or Patient is on ELTROXIN SUB-CLINICAL HYPOTHYROID SECONDARY HYPERTHYROID SECONDARY HYPOTHYROID PRIMARY HYPERTHYROID PRIMARY HYPOTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH NINE SQUARES MAJIC

4. www.drsarma.in 4 The Commandments Suspect hypothyroidism ever Growth and pubertal delay Unexplained depression TSH is the test in Hypothy. TSH, FT 4 to confirm Dx. Nine square magic Test cord blood for TSH All obese patients TSH a must For all pregnant -test TSH, FT4 Postmenopausal 15% Hypothy Start low and go slow Use L-Thyroxine only Always on empty stomach Thyroxine - avoid empirical use

5. www.drsarma.in 5 Algorithm for Hypothyroidism Measure TSH Elevated TSH Normal TSH Measure FT4Considering Pituitary Normal LowNoYes Sub-clinical hypo TPO + TPO - T4 replAnnual FU Primary hypothyroid TPO + TPO - No tests Measure FT4 Low Normal No tests Evaluate Pituitary Sick Euthyroid Drugs effect Hashimoto Others

6. www.drsarma.in 6 Algorithm for Hyperthyroidism Measure TSH and FT4  TSH,  FT4 Measure FT3 Primary (T4) Thyrotoxicosis High Pituitary Adenoma FNAC, N Scan Normal  TSH, FT4 N  TSH,  FT4 N TSH, FT4 N T3 Toxicosis Sub-clinical Hyper Features of Grave’s Yes Rx. Grave’s No Single Adenoma, MNG Low RAIU  RAIU Sub Acute Thyroiditis, I 2, ↑ Thyroxine F/u in 6-12 wks

7. www.drsarma.in 7 Causes of Hyperthyroidism 1.Graves Disease – Diffuse Toxic Goiter 2.Plummer’s Disease – Toxic MNG 3.Toxic phase of Sub Acute Thyroiditis - SAT 4.Toxic Single Adenoma – STA 5.Pituitary Tumours – excess TSH 6.Molar pregnancy & Choriocarcinoma (↑↑ βHCG) 7.Metastatic thyroid cancers (functioning) 8.Struma Ovarii (Dermoid and Ovarian tumours) 9.Thyrotoxicosis Factitia ; INF, Amiodarone, SSRIs

8. www.drsarma.in 8 Summary of Hyperthyroidism Any age 35 - 50 > 50 20 - 40 Age 15% 5% 20% 60% % Treatment RAIU Pain Enlarged Hyperthyroidism NSAID, Steroids. ↓↓ YesNone S Acute Thyroiditis RAI, ATD ± NoneSingle Single Adenoma RAI, Surgery ↑ Pressure Lumpy Toxic MNG ATD – 18 m ↑↑ NoneDiffuse Graves (TSI Ab eye, dermo, bruit) TSH is markedly low, FT4 is elevated

9. www.drsarma.in 9 Anti Thyroid Drugs (ATD) Imp. considerationsMethimazolePropylthiouracil EfficacyVery potentPotent Duration of actionLong acting BID/ODShort acting QID/TID In pregnancyContraindicatedSafely can be given Mechanism of actionIodination, Coupling Conversion of T 4 to T 3 No actionInhibits conversion Adverse reactionsRashes, NeutropeniaRashes, ↑ Neutropenia Dosage20 to 40 mg/ OD PO100 to 150mg qid PO

10. www.drsarma.in 10 Algorithm for Thyroid Nodule Thyroid Nodule Low TSH Normal TSH TC 99 Nuclear Scan FNAC or US guided biopsy Hot Nodule Cold Nodule RAI Ablation, Surgery or ATD Non diagnostic – repeat FNAC Surgery or Cytology Cyst Benign T4 suppression Suspicious or follicular Ca Malignant Surgery 4%10%69%17%