Hyperthyroïdie

The hyperthyroïdie (also called thyréotoxicose or thyrotoxicose ) is the clinical Syndrome caused by an excess of Thyroxine free circulating (FT4) or of free Triïodothyronine (FT3), or both.

At the human ones, the main causes are the Maladie of Basedow (causes most frequent: 70 80% of the cases), the toxic Adenoma of thyroid the, the toxic Goiter multinodulaire, and the subacute Thyroïdite.

Signs and symptoms

The majority of the signs remain nonspecific or can be discrete. The hyperthyroïdie can appear by whole or part of the following signs:

General signs

a weight loss in spite of an appetite preserved (polyphagia) or increased,
a heat felt like unbearable (thermophobie), with thirst,
a Asthenia.

Cardiorespiratory signs

a fast pulse (Tachycardia);
of the Palpitations;
breathlessness (Dyspnea);
a irregular pulse which can correspond to a auricular fibrillation.

The whole can become complicated is:

of a Cardiac failure with high banc;
or of thoracic pains being able to evoke a Angina pectoris.

Digestive signs

chronic Diarrhea;
Nauseas or vomiting.

Neurological signs

Reduction in the muscular force (Myopathy endocrinienne) with sometimes reduction in the size of the muscles (muscular Atrophy );
Tremor S ends of the ends;
depression or irritability;

In the serious forms, the hyperthyroïdie can involve:

a Coma;
of the abnormal movements in the form of Chorée;
of the behavioral problems which can resemble a Psychosis.

Signs cutaneous

Skin luisante, heat and wet
sometimes, loss of hair (Alopécie, sign of the tail of the eyebrow)
isolated itching

Endocrino-sexual signs

Impotence
increase in the size of the centres (Gynécomastie)
Infertility

Others

It can become complicated of a reduction in calcium contents of the bones (secondary Ostéoporose).

Biological elements

reduction in the rate of blood Cholesterol (hypocholesterolemy)
Anemia and total reduction in the white globules (Neutropenia)

Thyroid gland

According to the cause of the hyperthyroïdie one observes a Goître, a thyroid Nodule, a thyroid Atrophie…

Diagnosis

The diagnosis is established by a blood examination: measure rate of TSH in blood. A ploughed up rate of TSH is specific of a peripheral hyperthyroïdie (vast majority of the hyperthyroidies, secondary to an attack of thyroid). The diagnosis is confirmed by a measurement of the rate of T3 free and blood free T4 which one finds increased.

Once the made diagnosis, it remains to seek the cause. It is essential to proportion the specific Anticorps (TRAK, anti-thyroglobuline, anti thyroperoxydase or anti TPO) and to carry out an examination of imagery of the thyroid one: echography (by ultrasounds) or Scintiscanning (by injection of a radioactive isotope which is fixed on thyroid gland and whose radiation is detected by a camera with scintillations). those Ci specify the aspect of gland and the geographical distribution of its activity (fixing with the scintiscanning)

Causes

The disease of Basedow

The Maladie of Basedow is the first cause of hyperthyroïdie in term of frequency. It is more frequent at the young woman. One finds in a nonconstant way a breath with the Auscultation of the thyroid gland which is increased by volume, a discrete swelling of the soft parts of the leg ( myxœdème pre-tibial ) or slightly prominent ocular spheres (Exophtalmie). The diagnosis is made in the presence of TSI ( Thyroid stimulating immunoglobulins ) in the blood of the patients to which the structure is close to that of TSH, and thus stimulating the production of thyroid hormones by gland).

The toxic nodule

the toxic Nodule Plummer is evoked in front of the nodule isolated from the thyroid gland which can sometimes be palpated and especially, by the radioactive Iodine fixing of this last in an exclusive way to the thyroid Scintigraphie, the remainder of gland being visualized more. It becomes an important cause of hyperthyroïdie in the elderly.

The thyroïdite

It can be:

infectious (Thyroïdite of Quervain in a context grippal) or post operational;
auto-immune as at the time of has Thyroïdite de Hashimoto with the presence of anti-thyroglobuline Antibody and anti-receiver with the TSH
to occur after a childbirth (enough generally attends since it concerns up to 10% of the parturients, very discrete and curing without after-effect).

It evolves sometimes to a hypothyroïdie (reduction in the thyroid hormones) regressive.

The scintiscanning then shows the complete absence of fixing of radioactive iodine ( white scintiscanning ).

Other causes

the catch of thyroid Hormone in too high quantity.
the goître multinodulaire with the clinical examination of the gland
the Cancer of thyroid the advanced.
Side effect of the catch of certain drugs (Amiodarone).

Treatment

Surgery

It consists of the ablation of the totality or most of thyroid gland. The surgery must respect the glands Parathyroïde S of small sizes and located behind the thyroid one. It must also pass apart from the recurring Nerf passing behind of gland, its section being able to involve a change of the voice (Dysphonie), this nerve innervant the vocal cords.

Radioactive iodine

The ingestion of radioactive Iode (Iodine 131) will be fixed on thyroid gland, thus destroying the latter. This treatment is proposed only with certain forms of disease of Basedow and is naturally ineffective in the event of nonfixing of iodine on the gland (white scintiscanning).

It exposes at the risk of Hypothyroïdie (as the surgery in addition) which is easily treated by the catch of thyroid hormones.

Antithyroïdiens of synthesis

It is about drug inhibiting the production of thyroid hormones, like the Méthimazole, the Carbimazole or the Propylthiouracil. The time of effectiveness can be long

Nonspecific treatments

In the event of pains, a Antalgique can be given, in the same way in the event of Fièvre (Antipyrétique).

the Bêta-bloquant S slow down the heart and decrease palpitations as well as the tremors.

In the animals

It one of the hormonal diseases most frequent of the cats, is often caused by a benign Tumeur (noncancerous) of the thyroid one. This disease was described for the first time in the Seventies.

See too

hyperthyroïdie|hyperthyroïdie

Hypothyroïdie

External bonds

Hyperthyroidism To precede

References

'' Diagnosis and management off thyrotoxicosis '', E Pearce, BMJ 2006; 332: 1369-1373

Simple: Hyperthyroidism

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