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HIPERTIROIDII. HYPERTHYROIDISM. Increased serum levels of thyroid hormones, - Surgical correction is frequently appropriate. NORMAL THYROID FUNCTION. The follicular cells- T3, T4 T3, T4 bind with thyroglobulin, stored on the gland until released onto the bloodstream
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HYPERTHYROIDISM • Increased serum levels of thyroid hormones, - Surgical correction is frequently appropriate
NORMAL THYROID FUNCTION • The follicular cells- T3, T4 • T3, T4 bind with thyroglobulin, stored on the gland until released onto the bloodstream • Release is under the control of TSH and TRH • A feed-back mechanism regulating T3, T4 release is related to the level of circulating T3, T4.
HORMONAL ACTION • The thyroid hormones: - increase the metabolic rate, - increase the O2 consumption, - increase glycogenolysis, - enhance the actions of catecholamines • The result is: • Increase in the PR, CO. • Nervousness, irritability, muscular tremor, muscle wasting These effects can be blocked by the use of beta-blockers
HORMONAL ACTION • The parafollicular or C-cells- produce thyrocalcitonin • Thyrocalcitonin action: - to lower serum calcium and phosphate concentration, - reduces bone resorption - in the kidney accelerates calcium and phosphate excretion:
THYROID GLANDCLINICAL EXAMINATION • Hyperthyroidism • Symptoms: dyspnea on effort, palpitation, tiredness, preferance for cold, sweating, nervousness, weight loss, good appetite • Signs: palpable thyroid, exophtalmos, lid lag, hyperkinesis, finger tremor, hot and moist hands, rapid PR
INVESTIGATIONS • TSH- raised in primary hypothyroidism and after treatment of thyrotoxicosis by surgery or radioiodine, - reduced in hyperthyroidism • Free T3, T4- radioimmunoassays, • Radioiodine uptake, • Thyroid isotope scanning • Ultrasonography, CT, MRI • Fine needle aspiration cytology • Thyroid autoantibodies (ab.tothyroglobulin)
Thyroid scintigram • Autonomous adenoma in the right lobe of the struma. • The test substance accumulates almost exclusively in the range of the autonomous adenoma. • The other areas of the struma show a considerable reduced accumulation of activity.
GOITERENLARGEMENT OF THE THYROID GLAND • Simple goiter - diffuse hyperplastic goitre, - nodular goitre • Toxic goiter - diffuse (Grave’s disease), - toxic multinodular goitre, - toxic solitary nodule • Neoplastic goiter - benign, - malignant • Thyroiditis - subacute (de Quervain’s), - autoimmune(Hashimoto’s), - invasive fibrous thyroiditis (Riedel’s) - acute suppurative
HYPERTHYROIDISM • Common causes: - diffuse toxic goitre (Graves’s disease), - toxic multinodular goitre (Plummer’s disease), - toxic solitary nodule, - exogenous thyroid hormone excess, - thyroiditis
HYPERTHYROIDISM • Rare causes: - metastatic thyroid carcinoma, - pituitary tumour secreting TSH
GRAVE’S DISEASE • The most common cause of hyperthyroidism • It is an immunological disorders • Thyroid stimulating antibodies (IgG type) bind to the TSH receptor of the thyroid cells- excess of the thyroid hormones • The thyroid gland hypertrophies • Diffuse enlargement
GRAVE’S DISEASEClinical Diagnosis • Symptoms and signs of thyrotoxicosis result from excess thyroid hormones: • Cardio vascular • Neurological • Metabolic • Exophtalmos • Diffuse enlargement of the thyroid
GRAVE’S DISEASE • Ophthalmopathy- two major components: -Non-infiltrating ophthalmopathy-sympathetic activity: - upper lid retraction, - a stare, - infrequent blinking -Infiltrative ophthalmopathy- edema of the orbital contents, lids, periorbital tissue, cellular infiltration within the orbit
HYPERTHYROIDISMPREOPERATIVE PREPARATION • Surgery must be done in the euthyroid state • ATD for a period then discontinue • Betablockers to control cardiac symptoms • Lugol’s solution, 10 days, will diminish the peroperative hemorrhagic risk
GRAVES’ DISEASETREATMENT • To restore the euthyroid state: • Antithyroid drugs + beta-blockers • Radioactive iodine - distroys overactive tissue • Surgery - bilateral subtotal/total thyroidectomy
Recurrent Grave’s disease after subtotal thyroidectomy, nodule at the piramidal lobe
Nodules with cystic degeneration after subtotal thyroidectomy
MULTINODULAR GOITREMANAGEMENT • Hyperthyroid- iodine scan • Large- ATD & surgery • Small- iodine therapy • Euthyroid • No dominant nodule-observe • Dominant nodule-FNAC • Benign, no sy-observe • Malignant- surgery • Suspicious- surgery • Inadequate- repeat FNAC • Retrosternal- surgery • Cosmetic- surgery
SOLITARY THYROID NODULEMANAGEMENT • Hyperthyroid- FNAC & isotope scan • Greater than 3 cm.- surgery • Less than 3 cm.- iodine therapy • Euthyroid- FNAC • Benign-no pressure sy.-observe, repeat FNAC in 6 months • Benign- with pressure sy.- surgery • Thyoiditis- T4 treatment • Suspicious- surgery • Malignant- surgery • Inadequate FNAC- repeat • Cystic benign- observe, review in 6 weeks • Cystic malignant- surgery
TOXIC SOLITARY NODULETREATMENT • This condition is caused by a single autonomous thyroid nodule • Best option- surgery- unilateral thyroid lobectomy
POSTOPERATIVE COMPLICATIONS • 1. Postoperative bleeding • 2.Postoperative thyrotoxic crisis • 3.Postoperative voice changes • 4. Hypoparathyroidism • 5. Hypothyroidism
POSTOPERATIVE BLEEDING • Postoperative bleeding • there is always a risk of postop .bleeding, • it is rare but sometimes dramatic • The bleeding may occur in one of two sites, • deep to the myofascial layer in relation to thyroid vessels-evacuation must be done quickly - deep to the skin flaps, from veins • Compressive hematoma- respiratory embarrasment- evacuation is mandatory
POSTOPERATIVETHYROTOXIC CRISIS • Serious complication-where there has not been adequate preop.preparation • It occurs within the first 24 hours of thyroidectomy • Symptoms: confusion, hyperactive, fever, profuse sweating, rapid PR. • Treatment: beta-blockers, iv steroids, iodine
POSTOPERATIVE VOICE CHANGES • Rare due to any damage to recurrent laryngeal nerves- this occurs in less than 1% • Probably minor changes in the muscles around the cricoid and thyroid cartilages are the most important, inevitable with the mobilization of the gland • Trauma to external laryngeal nerve- cricothyroid muscle- voice change- difficulty in achieving vocal cord tension • Trauma t the internal laryngeal nerve can occur where there is difficulty in mobilizing the superior pole
POSTOPERATIVE HYPOPARATHYROIDISM • Hypocalcemia- usually a consequance of a metabolic changes- re-entry of calcium into bone demineralized by hyperthyroidism (“hungry bones”) • Parathyroids are small and are not always easy to identify • The incidence of hypoparathroidism after surgery shoud be less than 1%
POSTOPERATIVE HYPOTHYROIDISM • All forms of treatment for thyrotoxicosis will produce a population of patients prone to develop hypothyroidism • Greatest risk after radioiodine therapy