Amiodaron-indutsirovannye tireopatiya (AMIT, AIT) – group of the pathologies of a thyroid gland caused by long reception of antiarhythmic medicine of an amiodaron. A current often asymptomatic, weak and moderate signs of a gipertireoz (irritability, feeling of heat, tachycardia, a tremor) or a hypothyroidism (a chill, weakness, drowsiness, bystry fatigue) sometimes develop. Diagnostics includes blood tests on , and tireotropny hormone, a stsintigrafiya and ultrasonography with doppler sonography of a thyroid gland. At a hypothyroidism hormonal replacement therapy is appointed, at a thyrotoxicosis – tireostatik or glucocorticoids.
Amiodaron treats antiarrhytmic medicines, is widely applied in cardiological practice at treatment of heavy arrhythmias, predserdny and ventricular premature ventricular contraction, WPW syndrome, arrhythmia at coronary and heart failure. Among side effects of a medicine are noted hyper - and a hypothyroidism or the amiodaron-induced tireopatiya. Synonymous names of frustration of this group – the amiodaron-induced tireoidita, the kordaron-induced tireopatiya. Prevalence of pathology among the patients accepting medicine makes about 30%. Gipertireoz is registered in regions with yododefitsity more often, there his frequency reaches 12%. The epidemiology of a hypothyroidism is higher in areas with moderate consumption of iodine, fluctuates from 6 to 13%.
The reasons of the amiodaron-induced tireopatiya
Amiodaron for 39% consists of iodine, is to benzofuranovy derivatives, on molecular structure similar to hormone tiroksiny. During treatment by this medicine the organism daily receives from 7 to 21 g of iodine at average physiological requirement of 200 mkg/days. Long reception of an amiodaron promotes violation of exchange of tireoidny hormones and a tireotropina that is shown hypo - or gipertireozy. Characteristic of this medicine – ability to collect in a liver and fatty tissue. The period of its semi-removal from an organism averages 53-55 days therefore the amiodaron-induced tireopatiya can develop 1-2 months later after end of a course of therapy. In risk group there are women of 35-40 years, people of advanced and senile age, and also persons with ShchZh dysfunctions.
Under the influence of an amiodaron metabolism of the iodated hormones, regulation of their level a hypophysis through TTG changes. Medicine breaks transformation of a tiroksin in in tireotropotsita by enzyme inhibition deyodinazy-II. Enzyme deiodinates an internal ring of a tiroksin, provides its conversion in , regulates the level of metabolic inert fraction T3, maintains concentration of this hormone in nervous tissue. Amiodaron reduces sensitivity of a hypophysis to influence of iodinated hormones. For this reason easy increase in a tireotropin at normal quantity of a tiroksin and triyodtironin is found in most of patients in an initiation of treatment – an eutireoidny gipertireotropinemiya.
Taking into account pathogenesis distinguish three types of the amiodaron-induced tireopatiya. At the amiodaron-induced thyrotoxicosis of the I type hormonal changes are connected with excess intake of iodine. The disease often arises against the background of predisposition to a multinodal craw and functional autonomy of ShchZh. Kordaron-indutsirovannye tireopatiya of the II type are more widespread, caused by toxic influence of medicine on tirotsita. The specific form of a tireoidit with a destructive thyrotoxicosis develops. The third option of a tireopatiya – a hypothyroidism. It is diagnosed for persons at whose blood there are antibodies to tireoidny peroxidase therefore as the pathogenetic mechanism provocation of an autoimmune tireoidit is supposed excess of iodine.
Symptoms of the amiodaron-induced tireopatiya
There are three options of a clinical picture of the tireopatiya provoked by reception of an amiodaron. At the induced hypothyroidism the pronounced symptomatology is absent. Most of patients does not notice any changes in health. Some report about emergence of day drowsiness and weakness, bystry increase of exhaustion when performing habitual work, periodic emergence of a chill. Decrease in body temperature, arterial hypotonia, delay of pulse, puffiness, violations of a menstrual cycle is objectively observed.
AMIT of 1 type is shown by a picture of the developed gipertireoz. Patients become irritable, uneasy, disturbing, experience difficulties with concentration of attention and storing of information, look forgetful, scattered. The tremor develops, inflows of heat in a body appear, sweating and thirst amplifies. Patients hard transfer a heat and closeness, lose weight, sleep badly at night. AMIT 2 types often has the erased symptoms as application of an amiodaron eliminates the symptoms of dysfunction of cardiovascular system characteristic of a thyrotoxicosis. Often the clinical picture is presented only by muscular weakness and decrease in body weight.
Therapy consequences amiodarony usually have reversible character, after cancellation of a medicine functionality of ShchZh comes back to norm. Resistant complications are caused by impact of excess amount of T3 and T4 hormones on heart: the course of the available arrhythmias worsens, stenokardichesky attacks become frequent, heart failure appears and aggravated. The thyrotoxicosis results in hypersensitivity of muscle cells of heart to influence of adrenaline, noradrenaline, dopamine that increases risk of ventricular arrhythmias. Iodinated hormones exert direct impact on kardiomiotsita, changing their electrophysiological properties and provoking fibrillation of auricles. At a long current of AMIT of the first type development of a dilatatsionny cardiomyopathy is possible.
At suspicion on a tireopatiya of the patients accepting direct to consultation to the doctor-endocrinologist. At the initial stage of inspection the expert analyzes the anamnesis, specifies duration of reception of antiarrhytmic medicine, its dosage, existence of pathologies of ShchZh. Complaints of patients are absent or correspond to a picture hypo - or a gipertireoza. The following techniques are applied to confirmation of the diagnosis and differentiation of various types of tireopatiya:
- Stsintigrafiya of a thyroid gland. The research radioisotopes of iodine is appointed by the patient with a thyrotoxicosis. For AIT-1 the normal or strengthened medicine capture is peculiar, at AIT-2 the reduced accumulation of iodine in ferruterous fabric is found.
- Ultrasonography of a thyroid gland. By results of ultrasonography and doppler sonography at tireopatiya of type 1 symptoms of a multinodal craw or autoimmune defeat of gland with the normal or raised blood-groove are diagnosed. Patients with tireopatiya of type 2 have a blood-groove which is often lowered or is not defined.
- Blood test (hormones and antibodies). At a hypothyroidism indicators of T4 are considerably lowered, the caption of AT-TPO is raised. AMIT 1 is diagnosed on the increased T3 level, T4, TTG at the developed clinical picture. Feature of AMIT-2 – substantial increase of the T4 level (from 60 pmol/L), moderate increase free T3 in a combination to ill-defined symptomatology or against the background of an asymptomatic current.
Treatment of the amiodaron-induced tireopatiya
Tactics of maintaining the patient in common is defined by the cardiologist and the endocrinologist. The Etiotropny direction of therapy is cancellation of an amiodaron, however in many cases it is impossible as the termination of reception of medicine provokes ventricular arrhythmia, is accompanied by risk of development of zhizneugrozhayushchy states. Normalization of level of T4 and T3 hormones becomes a problem of therapy. The choice of methods depends on a disease form:
- Gipotireotichesky AMIT. The manifest hypothyroidism is corrected by replaceable hormonal therapy. Medicines of a tiroksin are appointed sick. Duration of treatment varies taking into account compensatory opportunities of gland, expressiveness of an autoimmune component, a possibility of cancellation of an amiodaron.
- AMIT I. Treatment of a tireostatikama is carried out. Because of excess intake of iodine for suppression of production of hormones high doses of medicines are shown.
- AMIT II. At destructive processes in a thyroid gland glucocorticosteroids, for example, Prednisolonum are used. Course duration – up to 3 months.
- The mixed AMIT. At a combination of two forms of a thyrotoxicosis the heavy course of disease demanding simultaneous application of tireostatik and glucocorticoids is observed. In the course of treatment establish the prevailing tireopatiya type, cancel one of medicines.
At inefficiency of conservative treatment of the thyrotoxicosis provoked amiodarony the radical measures aimed at suppression of the ShchZh hormonal function are necessary. The total tireoidektomiya (surgical removal of gland) is carried out. To patients with the heavy cardiac pathologies which are a contraindication to surgery the radioiodine therapy causing death of tireotsit is appointed.
Forecast and prevention
The outcome of the amiodaron-induced tireoidit in most cases favorable, especially if exists a possibility of cancellation of antiarhythmic medicine. The hypothyroidism is successfully compensated by hormonal therapy, a thyrotoxicosis – tireostatika, glucocorticoids. For prevention of this state by the patient accepting once in half a year it is necessary to conduct blood test for determination of level of tireotropny hormone, a tiroksin, a triyodtironin. Results of laboratory tests allow the endocrinologist to estimate, the thyroid gland is how functional, to calculate risk of development of a tireopatiya.