Hyperthyroidism is actually a state of toxicity caused by excessive levels of thyroid hormones circulating in blood. It is also referred as thyrotoxicosis.
CausesThe main causes of hyperthyroidism are mentioned below:• Autoimmuneo Graves Disease (76%)o F>M, age 20-40o IgG auto antibodies bind TSH receptors T3 & T4o Leads to gland hyper function• Solitary NoduleA single nodule in thyroid gland which is usually euthyroid and rest of the gland is not palpable. • Toxic adenomaA solitary nodule when becomes hyper functioning leads to formation of toxic adenoma and it is autonomous functioning nodule.• Dominant Thyroid SwellingA swelling in thyroid when the rest of the thyroid gland is also enlarged and palpable.• Multinodular GoitreMultiple nodules or swelling formation in thyroid gland is MNG. It is irreversible state and is cured by surgery ( sub-total thyroidectomy )• Viral ThyroiditisIt results after the viral illness (CMV usually).
The antibodies against viral antigens or the antigens itself cross react with thyroid gland leading to transient state of hyperthyroidism.• Excessive Iodine IntakeExcessive iodine intake leads to increased uptake of iodine in colloid follicles and thus increased formation of thyroid hormones.• Drugs- AmiodaroneIt is an antiarrhythmic drug which has a structure analogous to T4 and it has large amounts of iodine.
It inhibits the conversion of T3 from T4.• Thyroid cancerFollicular CA, papillary CA, medullary CA and anaplastic CA are four types of CA which results in hyperthyroidism.• TSH secreting pituitary adenoma (rare)TSH secreting pituitary adenoma is a rare state in which there is a pituitary tumor which secrete excessive TSH. This TSH in turn stimulates thyroid gland way too much leading to hyperthyroidism.Symptoms:• Hyperactivity• Dysphoria• Irritability• Increased sweating• Heat intolerance• Fatigue• Palpitations• Weight loss with increased appetite• weakness• Polyuria• Diarrhea• Sexual dysfunctionSigns:• Sinus tachycardia• Atrial fibrillation• Tremor• Goitre • Palmer erythema• Warm, moist skin• Muscle weakness, myopathy• Pigmentation • Lid retraction or lag• Gynaecomastia• Exophtalmus• Pretibial myxedemaHyperthyroidism – Eye DiseaseGraves DiseaseIt is an autoimmune disorder in which there is diffuse enlargement of the thyroid gland.
In this disease there are antibodies against thyroid stimulating hormone receptors which results in hyper activation of the thyroid gland even in the absence of TSH stimulus. It is the most common cause of hyperthyroidism and the patient usually presents in middle ageThe signs and symptoms of Graves Disease are almost same as the other hyperthyroid states. In addition to that eye symtoms are a common manifestation too i.e, lid lag and lid retraction due to sympathetic over supply of the levator palpabrae superioris. Other signs and symptoms which are included are following :• Ophthalmoplegia• Exaphthalmos• Pretibial myxedema• Corneal Ulceration• Thyroid acropachyThe patient usually depicts positive Naffziger Mobius Joeffroy’s signs.Investigations:• Thyroid ProfileThyroid profile is the initial test to be performed.
Levels of TSH, free T3 and T4 are measured. TSH is decreased usually in cases of hyperthyroidism except in TSH secreting pituitary adenoma. T3 and T4 are increased.• FNACFine needle aspiration cytology is the choice of investigation in cases of single or discrete solitary nodule of thyroid.• UltrasoundUltrasound is done to see the retrosternal extension of thyroid. Clinically the retrosternal extension is assessed by asking the patient to raise her hands above head for 1 to 2 minutes.
This leads to appearance of prominent veins on neck and facial congestion. This sign is called ‘pemberton’s sign’• Thyroid ScanThyroid scan is done whether the nodule in thyroid is toxic or non-toxic i.e, whether it is cold, hot, warm.CT-scan and MRI are done for staging of cancer and to find any involved lymphnodes.
TreatmentTreatment consists of anti-thyroid drugs. Various options are available such as• Methimazole• Propylthiouracil• CarbimazoleThey have different metabolism of action.The dose is 50 µg given thrice a day till clinical effects are achieved after which the lose is reduced to 10 µg.
Radioactive IodineRadioactive Iodine is the first line treatment option in old age. The radioactive Iodine is taken up by the thyroid gland and it destroys the gland over a period of time.It is contraindicated in pregnancy, young age and children and in those patients of Graves’ Disease who have eye signs because it aggravates ophthalmologic symptoms.SurgerySurgery is the definite choice.
It is first line of choice in young age and also in old age if radioactive iodine is not successful.Sub-total thyroidectomy8g of thyroid tissue is left on each side of isthmus to prevent hypothyroid state after surgery.Total thyroidectomyIt is not recommended these days because it results in hypothyroidism.