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THYROID (IN THYROID DISEASE (thyroid scintogram - iodine 131 injected scan…
THYROID
IN THYROID DISEASE
thyroid scintogram - iodine 131 injected scan via gamma ray - hot nodule takes it up = hyperactive gland. cold = cyst or tumour
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US asssess whether mass is solid or cystic, unifocal or multifocal and can be used to direct needle
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HASHIMOTOS DISEASE
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microscopically - diffuse infiltration w/ lymphocytes, inc fibrous tissue and diminished colloid
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HYPERTHYROIDISM
HX
Irritable and nervous and cant keep still
inc appetite yet there is loss of weight
DM
diarrhoea
pt prefers cold environment
palpitation due to tachycardia or atrial fibrillation may occur
thyroxine potentiates actions of adrenaline - and many of the features of hyperthyroidism represent inc activity of the sympathetic nervous system
O/E
thyroid usually smoothly enlarged but not invariably so. may be highly vascular and demonstrate a bruit and thrill
EYE
exopthalmos
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may respond to corticosteroids; surgical decompression of orbit with suture of eyelids across the eyeball (tarrsorrhaphy) may be required
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HANDS
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Tachycardia - may be atrial fibrillation and indeed pt may present with HF - rapid sleeping pulse rate permits differentiation of hyperthyroidisn from an acute anxiety state which wouldnt have elevation in sleep
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onycholysis - nail lifts off nail bed a condition also seen in psoriasis and with some fungal infections
pretibial myxoedema - thickness of subcutaneous tissues in front of tibia, is a rare feature
AETIOLOGY
primary (grave's)
young women, no preceding hx of goitre, exopthalm, irritable, tremor, opthalmoplegia
primary = due to action of autoantibodies which bind to and stimulate TSH receptor
secondary
overactivity developing in an already diseased and hyperplastic gland
disease of middle age with pre-existing euthyroid goitre
gland is nodular and no eye changes
symptoms more CV, often present HF w/ AF - nervousness, irritability and tremor may be present
RIEDEL'S THYROIDITIS
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mistaken clinically for thyroid carcinoma - hard texture and apparent infiltration of neighbouring muscles but histologically gland is replaced by fibrous tissue containing dense lymphoplasmacytic infiltrate
TREAT - high dose steroids may be effective but resection of a portion of gland may be required if symptoms of tracheal compression develop
CONGENITAL ANOMALIES
Ectopic thyroid tissue results from failure or incomplete descent of the diverticulum originating in the floor of the pharynx
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a radioiodine scan should be performed to ensure that there is normal thyroid tissue present in the correct place before the lump is removed
THYROGLOSSAL FISTULA
presents as an opening onto the skin in the line of the thyroid descent, in the midline of the neck
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THYROGLOSSAL CYST
forms in embryologial remnants of the thyroid and presents as afluctuant swelling in or near midline of the neck
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TREAT
removed surgically, together with remnants of the thyroglossal tract and the body of the hyoid bone
PATHOLOGY OF GOITRE
MULTINODULAR
principal cause believed to be a functional heterogeneity of follicular cells with some having higher growth potential than normal follicular cells - some may even replicaate in absenc of TSH = leads to varied appearance of gland
FACTORS ASSOCIATED WITH DEVELOPMENT:
female
elevated TSH secondary to iodine deficiency or natural goitrogens
nodular goitres may produce a normal amount of T4 but sometimes excessive T4 production results in hyperthyroidism
in this conditon (secondary hyperthyroidism) radioactive iodine-131 is the treatment of choice in such cases
SYMPTOMS
Enlarging thyroid can produce pressure symptoms including dysphagia
breathlessness - exertion, bend forward
orthopnoea - weight presses when lie flat
hoarseness - recurretn laryngeal nerve
stridor - press on both recurrent laryngeal nerves or sig trach compression
facial swelling - venous engorgement esp on raising arms - PEMBERTON'S SIGN
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CT of neck and thoracic inlet to define size of goitre including retrosternal extension and to identify presence of tracheal compression
COMPLICATIONS
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haemorrhage into a cyst, producing pain and inc swelling (which may produce sudden tracheal compression
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HYPERPLASIA
in primary hyperthyroidism (Grave's disease) the thyroid is uniformly enlarged and there is hyperactivity of the acinar cells with reduplication and infolding of the epithelium
the gland is very vascular and there is little colloid to be seen
lymphocyte infiltration is usually a predominant feature
TREAT GOITRE
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HYPERTHYROIDISM
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RADIOACTIVE IODINE
2-3MTHS BEFORE EUTHYROIDantithyroid drugs w/ or w/out b-blocker may be used to control symptoms during this time
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THYROID TUMOURS
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THYROID CARCINOMA
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papillary and follicular cancer together referred to as differentiated thyroid cancer= 3/4 of cancers - curable when detected at early stage
specialist surgery, radio iodine ablation, TSH suppression and finally use of thyroglobulin as a thyroid specific tumour marker
half of all thyroid cancer deaths due to resp failure secondary to either pulmonary nets or airway obstruction
PATHOLOGY
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medullary carcinoma
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assoc MEN II asssoc with phaechromocytoma, either parathyroid tumours or neurofibromas
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HYPOTHYROIDISM
CONGENITAL
born with little or no functioning thyroid - infanted is stunted and mentally subnormal, puffy lips, large tongue, protuberant abdo, umbilical hernia
ADULT
usually affects women, middle aged/ elderly
pts have a slow, deep voice and are usually overweifht and apathetic, with a dry coarse skin and thin hair, esp lat third of eyebrows
in contrast with hyper - myxoedematous pts usually feel cold in hot weather, brady and constipated
they are often anaemic and may suffer from heart failure owing to myxoedmatous infiltration of heart