THYROID GLAND

THYROID GLAND

Begashaw M (MD)

Anatomy

Goiter

Generalized enlargement of the thyroid gland which is normally impalpable

Classification

1. Simple-Euthyroid _Diffuse hyper plastic

_(Multinodular)2. Toxic_Diffuse - Grave’s disease_Nodular_Toxic adenoma

3. Neoplastic _ Benign _Malignant4. Inflammatory _Autoimmune_Infectious_Acute –bacterial/viral_Chronic -tuberculous

Thyroid lesions

Simple Goiter

Patho - physiology enlargement of the thyroid glandstimulation of the thyroid gland by high

levels of circulating TSH common in Females

Etiology

_Iodine deficiency _Goitrogenscabagge_Drugs iodine,lithium_Defective hormone synthesis_peripheral resistance to thyroid hormone

Diffuse hyper-plastic goiter

Persistent stimulation by TSH causes diffuse hyperplasia of the thyroid gland

Soft, diffuse & largeUsually occurs at puberty , pregnancy Areas of active lobule & inactive lobules

Goiter –simple

Nodular goiter Nodular goiter -solitary -multinodular Nodule -colloid when filled with colloid -cellular Secondary changes -cystic degeneration -hemorrhage -calcification

Diagnosis

Clinical presentation_Discrete swelling in one lobe -Solitaryisolated -Dominant noduleabnormality Elsewhere_smooth, firm_painless _moves with swallowing _ euthyroid

Investigation

TFT T3, T4, TSH CXR/Thoracic inlet x-rayscalcification,

tracheal deviation & compression Thyroid antibody titers FNACytology

Complications

Compression stridor, dysphagia, pain, & hoarseness

Secondary thyrotoxicosisCarcinoma malignant changes of the

follicular type

Retrosternal goiter

Prevention

Introduction of iodized salt Thyroxin of 0.1mg dailyNodular stage is irreversible

Indication of surgery

CosmeticTracheal compressionWhen malignancy cannot be excluded Options of surgery _Near total thyroidectomy _Subtotal thyroidectomy

Toxic goiters

Thyrotoxicosis - increased metabolic rate due to high level of circulating thyroid hormone

8X more commonly seen in females than males

Clinical features

symptoms _Loss of weight in spite

of good appetite_preference of cold_Palpitation_Tiredness_Emotional liability

signs_excitability_presence of goiter_hot & moist palms_exophthalmus in

primary type_tachycardia with

cardiac arrhythmia

Diffuse Toxic GoiterGraves Disease

Is a diffuse vascular goiter appearing at the same time as symptoms of hyperthyroidism

Occurs in younger womenFrequently associated with eye signsHypertrophy & hyperplasia are due to

abnormal TS antibodiesF > M = 7:1

Graves disease

Toxic nodular goiter

A simple nodular goiter is present for a long time before hyperthyroidismsecondary thyrotoxicosis

Seen in middle aged/elderly people Less frequently associated with eye signsNodules are inactive Intermediate thyroid tissue is involved in

hyper secretion

Toxic nodule

Solitary hyperactive nodule which may be part of a generalized nodularity or a true toxic adenoma

is autonomous not due to TS antibodiesnormal thyroid tissue surrounding the

nodule is suppressed & inactive

Diagnosis

Clinical picture T3,T4,TSH Isotope scanning

TreatmentAntithyroid drugsSurgeryRadioiodine

Anti thyroid Drugs

used to resume the patient to a euthyroid state maintain this for a prolonged period

cannot cure a toxic nodule

Surgery

Preoperatively, the patient must be prepared with antithyroid drugs so that the patient becomes euthyroid

Subtotal thyroidectomy

Post-operative complications

HemorrhageRespiratory obstructionRecurrent laryngeal nerve paralysisThyroid insufficiencyParathyroid insufficiencyThyrotoxic crisis (storm)Wound infection

Thyroid Tumour BenignFollicular adenoma Malignant Primary - EpithelialFollicular,Papillary,Anaplastic- Para follicularMedullary- Lymphoid cellslymphoma Secondary- Metastatic- Local infiltrations

Benign Tumours

Follicular adenomas-solitary nodules -distinction between a follicular carcinoma &

adenoma can only be made by histological examination

-Treatment Lobectomy

Malignant Tumors

Clinical feature-Thyroid swelling-Enlarged cervical lymph node -papillary

carcinoma-Recurrent laryngeal nerve paralysis –locally

advanced disease-Anaplastic-hard, irregular, infiltrating

Thyroid Cancer

Investigations

TFTT3,T4,TSHFNAAntibody assayRadio isotope scanning

Treatment/Prognosis

_Surgerytotal thyroidectomy_Prognosis Histological type, age, extra

thyroid spread, & size of tumor_ Males > 40 yrs of age & Females >50 yrs

have worse prognosis_Distant metastatic diseaseworse prognosis

Anaplastic Carcinoma

Mainly in elderly womanLocal infiltration Epread by lymphatics & blood streamExtremely lethal tumors with death occurring in

most cases within month Present in advanced stages with tracheal

obstructionRadiotherapy