Hypothyroidism, goitre and thyroid nodulesHypothyroidismHypothyroidismCauses: Hashimotos thyroiditis (autoimmune)Surgical thyroidectomyAfter radioiodine therapyIodine deficiency, enzyme defectsClinical: Symptoms, signs, spot diagnosisCold intolerance, puffy eyes/face, wt gain, tiredness, constipation, muscle aches, hoarseness, menorrhagia, dry skin, carpal tunnel syndromePuffy appearance, bradycardia, slowness, slow-relaxing reflexes, dry skin/hair, carotonaemiaHypothyroidismTests Primary hypothyroidism:- Elevated serum TSH- Low serum T4 and T3-Positive destructive thyroid antibodies(antiperoxidase, antimicrosomal, antithyroglobulin)- ECG, CK, sodium, cholesterol Secondary hypothroidism: -low serum T4 T3 but low/normal TSHTreatment of primary hypothyroidism Incremental thyroxine replacement (not T3) Full replacement = approx 0.1-0.15mg/d Monitor by normalisation of TSH Expect clinical response to be gradual Dont miss secondary hypothyroidism (but also take care to exclude sick euthyroid syndrome and effects of medication on thyroid tests) Care in the elderly or those with ischaemic heart disease Children - monitor growth and bone ageGoitreThyroid nodules and goitre(goitre = an enlarged thyroid) Bilaterally enlarged thyroid:1. Simple diffuse colloid goitre2. Multinodular goitre3. Graves disease, Hashimotos disease4. Others (iodine lack, enzyme defects etc) Discreet thyroid nodules1. Multiple or solitary nodules2. Causes: colloid nodules, cysts, adenomas, carcinomasIodine deficiency goitreDiffuse-appearing goitre(actually multinodular on scan)Multinodular goitreInvestigation and management of goitre Thyroid function tests, antibodies, delineate nature of goitre by scan, cytology if needed, thoracic inlet Xray, flow-volume vitalography, ENT opinion if voice problems Treat any specific cause (thyrotoxic Graves disease, autoimmune hypothroidismetc) Observation Trial of thyroxine suppression (relatively ineffective) Surgery or 131I to shrink goitre size or if suspicious featuresThyroid scintigram 99mTcNormal thyroidThyroid scintigram multinodular glandInvestigation and management of thyroid nodules Ultrasound (size, echotexture, cyst formation, number, vascularity, punctatecalcification, lymph nodes etc) Aspiration cytology Thyroid function, antibodies Management:- Observe, cyst aspiration, trial of T4 suppression (rarely effective), surgery (if concern or suspicious features)Thyroid ultrasound - isoechoicthyroid noduleThyroid cyst with nodule on wallThyroid nodule99mTc scintigraphy and ultrasoundSolitary toxic nodule(functioning adenoma)Cytology - colloid nodule(Note: colloid++, even regular nuclei, no crowding)Thyroid nodule - papillary carcinomaNote: large squamous-like cells, nuclear inclusions, no colloidThyroid nodule - follicular neoplasmNote: Overlapping and crowding, pseudofollicles, inspissatedcolloidThyroid cancer Papillary, follicular, Hurthle cell, medullary, anaplastic Treatment by total thyroidectomy by an experienced surgeon Post surgical radioiodine usually indicated with or without external beam radiotherapy Permanent thyroxine replacement, monitor serum thyroglobulinHyperthyroidism(Thyrotoxicosis)Hyperthyroidism ~ causes Diffuse toxic goitre(85%) Toxic nodular goitre Toxic adenoma or hot nodule Subacute thyroiditis AmiodaroneSymptomsweight lossincreased appetite heat intolerancetremorpalpitationsnervousnessfatigue muscle weaknessfrequent bowel motionsSignsgoitretachycardiaatrial fibrillationwastingthyroid bruittremormyopathyheart failureproptosisonycholysisThyrocardiacdiseaseHeat intoleranceAtrial fibrillationRight MCA embolusLeft hemiparesisNo goitreOnycholysisPatient history:Onycholysis A naildystrophy seen in chronic hyperthyroidism of any cause, typically on the ring fingers (Plummers nails)Suppressed TSH is the bestscreening test Normal TSH=0.4 4.0 mU/l Suppressed TSH< 0.004 mU/l Reduced TSH = 0.004 4.0 MU/Le.g. goitre, sickness, glucocorticoidsNormal TSH excludes hyperthyroidism in 99% of casesSerum thyroid hormonesfT4 ( n = 9-19 pmol/l)sensitive (95%)not specificraised by.. sicknessdrugs egamiodaroneSolitary T4-hyperthyroidism = 5%fT3 ( n = 2.5 6pmol/l)specific (99%) not sensitivereduced by.. sicknessdrugs egamiodaroneSolitary T3-hyperthyroidism = 5%Lymphoid follicles in the thyroid glandAutoimmune thyroid diseaseThyroid antibodies autoantibodies to many antigens titrereflects lymphocyte infiltration not causal of autoimmune dysfunction Anti-thyroglobulin (TgAb) Anti-thyroid peroxidase (TPO Ab) TSH receptor stimulating Abcauses adult, intrauterine & neonatal hyperthyroidism Normal thyroid scintiscan99Tc scanning pertechnetateanion competes with iodide trapping rate is related to T4 output pattern indicatesfunction inferior to ultrasound for structureScintiscan utility increased trapping in Graves or TNG absent in subacute thyroiditis absent in iodide contamination a guide tothyroid size & shape a guide to radioiodine therapy useful in detecting 131I uptake in metastases of thyroid cancerToxic nodulargoitre May complicate long-standing euthyroid nodular goitre. Iodides such as found in Xraycontrast, dyes, or kelp tablets may precipitate iodide-inducedhyperthyroidism. Toxic multinodular goitre Diffuse or simple colloid goitre Multinodular goitre Toxic nodular goitre~autonomy from polyclonal activating mutationsSolitary toxic (hot) nodule A benign neoplasm T3 hyperthyroidism in 5% Suppressed TSH, therefore.. Normal tissue inactive Treat with 131I or surgery..normal tissue wakes up. 4 and T3 high T4 and T3 normal99Tc uptake 3.2%1.2% (normal 10.5 nmol/lHypothyroid women need 1/3 extra T4 replacementNZ still has mild iodine deficiencyThyroid crisis ~ therapy Hyperthyroid ++ with fever, HR > 140, confusion Atenolol 50-100 mg bid Dexamethasone 8 mg stat & OD Carbimazole 30 mg stat & q8H LugolsIodine 5 drops 2hrs after CBZ, then TID Consider early surgeryHyperthyroidism Standard therapy of the typical case.. Atenolol 50 mg nocte ~ minority Early radioiodine treatment: when hypothyroid.. Carbimazole 15 mg bid Replace thyroxine to a normal TSH Diltiazem effective for rate control in AF Warfarin if AF chronic, abnormal 2D-echocardiogram,or age > 65