Thyroid

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Thyroid : 

Thyroid Hisham Salahuddin

Anatomy & General info : 

Anatomy & General info Parathyroid – 3 & 4 pharyngeal pouch, 50mg Parafollicular © Cells – neural crest via ultimobranchial body 20-25 g Anastomoses with tracheal and esophageal arteries Delphian (juxtathyroid nodes) level 6 – paratracheal 7, sup & inf thyroid veins, deep cervial 2-5 Trapping, oxidation, binding, coupling Thiocyanate & Perchlorate, Carbimazole & Thiouracil Binding TBG TBPA, free amount T3 0.03% few hours, T3 0.3% 4-14 days TSH-Rab more protracted TSH (16-24 vs 1.5-3 hrs) – virtually all cases of thrytoxicosis not due to autonomous nodules

Examination : 

Examination History: Age & Sex Family history of autoimmune disease Swelling: Duration Local symptoms: Discomfort during swallowing, dyspnea, pain, hoarseness Examination: General Symptoms: Neuro + CVS + Muscles Examination of the thyroid Pain, tenderness No. of nodules, Site, size, shape, tenderness, gross enlargement, bruit, consistency Related Examination: Eye signs (lid lag, lid retraction, exophthalamos, opthalmoplegia, chemosis) Cervical lymph nodes Short strong neck – retrosternal goiter; Pemberton’s Sign

causes : 

causes Hypothyroidism Endemic Cretinism Autoimmune Thyroiditis (Hashimoto’s Dx) Dyshormonogenesis Iatrogenic Agenesis, Supra-thyroid causes Surgery, Radioiodine, PAS, Brassica (cabbage, kale, rape), excess Iodines, Anti-thyroid meds Hyperthyroidism Primary or secondary Hyperthyroidism Toxic Adenoma Autoimmune Thyroiditis (Graves Disease)

Slide 9: 

Cancer Toxic Adenoma Papillary, Follicular, or Undifferentiated Medullary Carcinoma Malignant Lymphoma

Swellings : 

Swellings Diffusely enlarged gland Primary thyrotoxicosis Graves disease Thyroiditis (Hashimoto, de Quervian, Riedels) Hyperplastic goiter Multifocal carcinoma Solitary Palpable Nodule (Discrete Swelling) Cyst Toxic Adenoma Carcinoma Only palpable nodule of a multinodular goiter Multinodular Gland (Dominant Swelling) Hashimotos Multinodular Goiter (Secondary thyrotoxicosis) Anaplastic carcinoma Toxic Adenoma

Swellings & provisional Dx : 

Swellings & provisional Dx Hard texture: cystic or carcinoma Pain, sudden ↑ size: Ca or hemorrhage Smooth, firm, painless: Sporadic or endemic goiter Firm & rubbery: Hashimoto’s disease Soft, & diffuse: Diffuse hyperplastic Carcinoma Hard & irregular with apparent fixity With RLN horaseness & non-occlusive cough almost pathognomic Deep cervical lymphadenoathy on internal jugular vein + suspicious swelling: Papillary carcinoma (almost diagnostic) Discrete swelling male - ↑↑malignancy Discrete swelling teenage – provisionally Carcinoma

Investigations : 

Investigations Routine Toxic patient with a nodule or nodularity – localisation of overactivity to differentiate toxic nodule and toxic multinodular goiter Investigation of choice for discrete swellings Cannot diff. b/w follicular adenoma & carcinoma No role as 1st line investigation Toxic + Nodule Clinical suspicion or FNAC indicating malignancy, before subtotal resection TPO, TSH-RAb

Interpretation of investigations : 

Interpretation of investigations Thyroid Failure: ↓ T3, T4, ↑ TSH Developing thyroid failure: Low-normal T3, T4, ↑ TSH Toxic states: TSH ↓↓/undetectable

Radioiodine test : 

Radioiodine test Normal Graves Disease Hot & Cold Nodules Toxic Adenoma Thyroiditis 80% nodules are cold, of which 20% are malignant. Of hot nodules, only 5% are malignant.

management : 

management Depends on access to post-treatment care & availablability of thyroid replacement. Therapeutic Radio-iodine: Destroy thyroid cells, reduce vascularity, uptake by normal thyroid gland first Thyroid Medications: Long term remission with TSH-Rab. Failure rate 50%. Avoided post-op in sub-total thyroidectomy. Not curative for toxic adenoma. Carbimazole: Propylthiouracil: B-blockers: Control symptoms Surgery Total Resection: 2 x total lobectomy + isthmusectomy Subtotal resection: 2 x subtotal lobectomy + isthusectomy (8g) Near Total Thyroidectomy: total lobectomy + isthmusectomy + subtotaal lobectomy Lobectomy: total lobectomy + isthmusectomy

management : 

management

Indications of surgery : 

Indications of surgery Neoplasia FNAC Positive Clinical suspicion and any of the following Age, Male Sex, Hard texture, fixity, RLN palsy, Lymphadenopathy Recurrent Cyst (15%) Toxic Adenoma Pressure Symptoms Cosmesis Patient’s Wishes

Pre-op preparation : 

Pre-op preparation Biochemically euthyroid at operation Carbimazole 30-40mg, 8-12 wks B-blockers: Propanolol blocks T4 to T3 40 mg t.d.s or slow release OD Continue treatment 7 days post-op (do not interfere with thyroid synthesis) Iodine pre-op in case morning B-blocker is missed Investigations Thyroid function tests Laryngoscopy Thyroid antibodies Serum Calcium Isotope scan in toxic nodule (not total resection)

Post op complications : 

Post op complications Haemorrhage – deep cervical Respiratory obstruction – hematoma, collapse, kinking, edema RLN paralysis & voice change –transient, permanent, uni or bi lateral Thyroid Insufficiency Parathyroid insufficiency Thyrotoxic Crisis (storm) Wound infection Hypertrophic or keloid scar Stitch Granuloma Post-op 4-6 weeks calcium levels Voice and cord function 4 wks Volume of thyroid tissue left after subtotal resection: failure vs. recurrence (Graves)

Neoplasia : 

Neoplasia Papillary Carcinoma (60%) Lymphatic spread Capsule infiltration Microcarcinoma (occult carcinoma) Follicular Carcinoma (20%) Blood spread Mortality 2x Papillary Carcinoma Higher male incidence, higher metastases Differentiated thyroid carcinoma Anaplastic Carcinoma (10%) Medullary Carcinoma (5%) Calcitonin Malignant Lymphoma (5%) Anaplastic Metastasis to lung and bone

Staging & grading : 

Staging & grading T1: 1 cm or less (microcarcinoma) T2: > 1cm, < 4 cm T3: >4 cm T4: Extension beyond capsule Staging Over 45 Under 45 I: T1 M0 II: T2, T3 M1 III: T4, or any N1 IV: M1

Follow up : 

Follow up Thyroxine 0.01 – 0.2 mg daily Follow up TSH level < 0.1 mU (most tumors are TSH dependent) Repeated radioiodine T3 (short acting, TSH recovers quickly) T4 wait 8 weeks Radioiodine Useful in detected remnants & metastasis Unresectable disease, local recurrence, rising serum thyroglobulin More aggressive, more de-differentiated – less likely to pick up Thyroglobulin Detection of metastasis Indication for U/S and/or whole body scan

thyroiditis : 

thyroiditis Riedel’s Thyroiditis: Cellular fibrous tissue, may invade surrounding structures High dose steroids and thyroxine replacement De Quervian Thyroiditis Viral infection Pain in neck, fever, malaise Iodine uptake low Self Limiting Prednisone 10-20mg for 7 days Chronic Lymphocytic Thyroiditis Family history autoimmune disease Discrete swelling Development of Lymphoma

Take home : 

Take home Follicular adenomas should be removed. Total thyroidectomy should be done to decrease follow-up if possible. Antibodies & Thyroiditis may cause hypo or hyperfunctioning glands. FNAC investigation of choice for single swellings. Carcinoma is more likely to be a cold nodule. Eliminate diet and other medications as a cause of defective hormone synthesis. Follow up laryngeal function and calcium at follow up and monitor for deep cervical hematoma post-op.

Thank you!! : 

Thank you!!