Hyperthyridism

Hyperthyroidism (hyperthyroid syndrome) - complex of symptoms, which results from hyperfunction of thyroid gland with increased secretion of thyroid hormones and expose them on the body tissues.

Etiology

In over 90% of patients with hyperthyroidism is due to Graves' disease. Other causes of excess production thyroid hormones are thyroiditis, multinodular goiter, iodide-induced after lingering taking some drugs (e.g. amiodarone). Extra thyroidal source of thyroid hormone excess is due struma ovary or excess secretion of TSH which may originate from pituitary in case of tumor - choriocarcinoma or hydatidiform mole.

The factors which provoke the development hyperthyroidism include:

• inherited predisposition;

• acute and chronic psychical traumas;

• acute and chronic infections (flu, quinsy, measles, whooping-cough, tuberculosis, chronic tonsillitis, encephalitis, rheumatism);

• immunological disturbances;

• neuro-endocrine alteration in woman (pubertal period, pregnancy, lactation, climax);

• chronic disease of liver and kidneys, attended with disorders of metabolism of thyroid hormones.

Pathogenesis

The development of hyperthyroidism is explained by immunological theory. The production of IgG antibodies directed against the TSH-receptor on the thyroid follicular cell stimulates thyroid hormone production.

In blood there are increased concentrations of thyroxin and triiodthyronin that lead to disorders of metabolism - proteins, lipids carbohydrates. Increased tone of sympa­thetic nervous system causes the development of hyperkinetic type of hemodynamic. Heart rate, cardiac contractility, stroke volume and cardiac output are increased and peripheral resistance is decreased. These alterations are explained by direct chronotropic and inotropic effects of thyroid hormones. The appearance of ophthalmopathy is caused by rise in retrobulbar pressure due to elevated interstitial fluid content and chronic inflammation, proliferation of fibroblasts. The eye is displaced forwards - exophthalmos.

Clinical feature

The main symptoms of the hyperthyroidism: excitability, anxiety, nervousness, inability; increased sweating, heat intolerancy; fatigue, muscular weakness; despite normal or increased appetite loss of weight; dyspnea on exertion; exacerbation of asthma; palpitation, pains in heart region; escaped beat; thirst, anorexia, vomiting, diarrhea; loss of libido, impotence.

Objective examination. The condition of patient is satisfactory. In case of hyperthyroid crises may be life-threatening condition. The consciousness is clear, posture is active. The patient is characterized by fast changing of mood, impossibility to be concentrated, motor, emotional and vocal lability. Patient looks younger his age.

The face has specific signs: lively with widened eye slits, exophtalmos, excessive lacrimation, corneal ulceration, hyperemia of conjunctiva.

There are specific eye signs in patients with hyperthyroidism:

• upper lids are symmetrically retracted so that some sclera is visible;

• Kraus' sign (abnormally sparkling eyes);

• Ellinec' sign (pigmentation of eyelids related to adrenal insufficiency);

• Rosenbach` sign (shallow tremor of the closed eyelids);

• Greffe' sign (lid lag during fixing of slowly downward moving object);

• Mebius' sign (weakness of convergence or loss of ability to fix a object at short distance);

• Stelvag` sign (rare blinking, less than 6-8 times in a minute).

Dermopathy is characterized by moist, hyperemic skin with palmar erythema, spider naive, sometimes appearance pigmentation, vitiligo and giblet clubbing. The hair may become thin and fine in texture and alopecia can occur. The nail is soft and separated from the nail bed - onchyolysis. Perspiration is increased. In patient may be pretibial myxoedema in the form of pink coloured or purplish plagues on the anterior part of the leg, accompanied with itching. The muscles are atrophic, their force and tone are reduced.

Thyroid enlargement of some type is a common sign.

Classification of diffuse toxic goitre according to degree of enlargement of thyroid gland:

0 - there are no thyroid gland at palpation;

1 - at palpation enlarged isthmus of gland and slightly lateral lobes;

2 - thyroid gland is noticeable at swallowing, at palpation determined well;

3 – “thin neck” (enlarged thyroid gland is well noticeable at examination);

4 - the expressed goitre, sharply changing configuration of neck;

5 - degree is goitre of largeness.

The size and consistency varies according to the pathology caused hyperthyroidism. In Graves' disease the thyroid is twofold to fourfold enlarged slightly tender and the surface is usually smooth. The thyroid bruit or thrill related to increased thyroid blood flow are heard. Thyroiditis usually characterized by slight diffuse thyroid enlargement.

The affection of respiratory system in patient is uncommon. In severe hyperthyroidism may be pneumonia and abnormalities in respiratory function. Decreased vital capacity decreased pulmonary compliance, respiratory muscle weakness cause dyspnea, aggravation of bronchial asthma.

The Jeading signs of affection of cardiovascular system, which accompanied the hyperthyroidism at every stage are defined as thyroidtoxic heart. The apex beat displaced to the left, diffuse, high and strong. The main sign of hyperthyroidism is stable arrhythmic tachycardia more than 90 beats per minute. The heart sounds are loud. Functional systolic murmur can appear over all auscultative points. Pulse is high and fast (altus et celer). Functional murmur can be heard over a. carotis and v. jugularis. Systolic blood pressure is increased, diastolic blood pressure is decreased, pulse pressure is elevated. In case of constant longstanding atrial fibrillation in patients with hyperthyroidism may be complication in the form of heart failure with congestion in lesser and grater circulation.

Due to the increased motility of stomach and intestine appear the pain and hyperdefecation. Intestinal hypermotility lead to more rapid small and large intestinal transport, resulting in steatorrhea. Inactivation of thyroid hormones takes place in liver hence in condition of their excess circulation develop hepatic dysfunction with raised concentrations of enzymes. In severe course of disease the enlarged liver and jaundice are observed. Renal blood flow, glomerular filtration rate and secretory capacities are increased. The common sign are polydipsia and polyuria. Urine concentrating ability may be impaired due to the dehydratation. Neuromuscular signs of the hyperthyroidism: shallow symmetrical tremor of fingers when the hands are extended, but it may involve the arms, legs, tongue and head. The movements are rapid and low amplitude. Instability in the Romberg' posture, hyperreflexia, muscle weakness, proximal myophaty, increased reflexes of tendons are observed. Myopathy can also involve the respiratory and oropharyngeal musculature, causing difficulties in swallowing or hoarseness. After exercise may be the attacks of periodic paralysis. The signs of central nervous system dysfunction are anxiety, irritability, episodes of paranoia, impairment of cognitive function.

Disorders of endocrine system include gonadal dysfunction. In women menstrual cycles are normal, although some of them have oligomenorrhea or amenorrhea accompanied with infertility.

In men hyperthyroidism results in decreased potency and loss of libido. Gynecomastia may be observed.