HYPERTHROIDISM: Causes, Signs, Symptoms, and Treatment.

Causes, symptoms, treatment and signs of hyperthyroidism in the body.

What are the Overactive thyroid (HYPERTHROIDISM), Symptoms and causes in the body. It's Medication, test, diet, and diagnosis.

This indicates excessive thyroid hormones especially the T3 and T4 in the body system or circulation and it is associated with numerous diseases which include the graves disease, toxic adenoma and goiter e.t.c.

These thyroid hormones (T3 and T4) are mainly synthesized in the colloid and their physiological functions include normalization of growth and development, body temperature, energy level.

Its insufficiency leads to cretinism and myxedema, while excess of this hormone leads to hyperthyroidism. The T3 is three times more potent than T4 in heat production while T4 in the colloid is about four times more numerous than T3.

These thyroid hormones targets the following tissues ( heart, liver, bone, central nervous system).

The mechanism that causes myxedema is still not yet understood.

But it occurs if the hyposecretion of the thyroid hormones is during adult life subsequently leading to reduced metabolism, reduced mental and physical activity, increased blood pressure.

Accumulation of subcutaneous fluids and its symptoms include skin thickening, coarse skin, change in facial appearance, thickening nose, swollen lips, puffiness around the eyes, jelly-like infiltratios in subcutaneous tissues, slow speech, mental dullness, lethargy, mental problems, dry skin, yellow skin, swollen subcutaneous tissue, weight gain, constipation, thinning hair, brittle hair, bald patches, muscle pains.

While cretinism is a condition of severely stunted physical and mental growth due to unyreated congenital deficiency of thyroid hormones usually due to maternal hypothyroidism.

SYNTHESIS OF THYROID HORMONE.

The two materials involved in the synthesis of thyroid hormones are iodine and tyrosine.

In the synthesis of thyroid hormones, the iodide is transported to the thyroid gland by sodium iodide symporter, the iodide is the oxidized by thyroid peroxidise to iodine.

The iodine becomes attached to the thyroid residue (tyrosine) on the thyroglobulin and iodinates to form monoiodotyrosine and diiodotyrosine (MIT and DIT).

This process is known as organification. The iodotyrosine then come together to form the thyroid hormones which are triiodothyronine (T3) and tetraiodothyronine (T4).

SYMPTOMS OF HYPERTHYROIDISM.

They include:
Inability to sleep
Bulgy eyes
Increased sensitivity
Palpitation
Nervousness
Increased heartbeat
Weakness involving the muscles
Hand tremor
Mood swings
Dryness of the skin
Weight loss
Increased frequency of the bowel movement.

DIAGNOSIS.

Hyperthyroidism can be diagnosed by different ways, it can be diagnosed based on symptoms or carrying out physical examination or by carrying out blood tests to measure the level of thyroid hormones in circulation, or to measure the level of thyroid stimulating hormone.

TREATMENT OF HYPERTHYROIDISM.

The goal of therapy for hyperthyroidism is the reduce the synthesis and release of additional hormone. This therapy can be accomplished by;
REMOVAL OF PART OR ALL OF THE THYROID: this can be accomplished either surgically or by destroying the thyroid gland by beta particles emitted by radioactive iodine (131I) which is selectively taken up by the thyroid follicular cells.

INHIBITION OF THYROID HORMONE SYNTHESIS: the thioamides such as the methimazole, propylthiouracil, methylthiouracil and carbimazole are concentrated in the thyroid where they are inhibit the oxidative processes required for the oxidation of tyrosyl groups and the condensation of iodotyrosines to form T3 and T4.

BLOCKADE OF HORMONE RELEASE: a therapeutic dose of iodide inhibits the iodination of tyrosines but this effect only last for few days. It is not useful for long term therapy because the thyroid ceases to respond to the drug after a few weeks

DRUGS USED IN HYPERTHYROIDISM ARE:

THIOAMIDES: propylthiouracil, methylthiouracil, methimazole, carbimazole.

IODIDES: potassium iodide, sodium iodide
RADIOACTIVE IODINE: 131I
BETA-ADRENOCEPTOR BLOCKER: propranolol
THIOAMIDES
All thioamides inhibit peroxidise catalyzing reactions which include both iodine organification and iodotyrosines condensation.

PROPYLTHIOURACIL: it binds to thyroid peroxidise inhibiting the conversion of iodide to iodine, therefore it effectively inhibits the production of new thyroid hormones. It also inhibit T4 converting to T3. It is used in the management of hyperthyroidism due to overactive thyroid gland.

It interacts with acenocoumarol, anisinedione, dicumarol, warfarin reducing their anticoagulant effect and also with digoxin increasing its effects. It is given orally at the dose of 300-600 mg daily until patient becomes euthyroid, the dose can then be gradually reduced to a maintainance dose of 50-150 mg.

CONTRAINDICATIONS.

Large goitre
Pregnancy
Lactation
Hepatic impairment
Renal impairment.

ADVERSE EFFECTS.

Thyroid hyperplasia
Pruritic maculopapular rash
Agranulocytosis
Alopecia
Jaundice
Hepatic necrosis
Hepatitis.

2.CARBIMAZOLE: it decreases the uptake and concentration of inorganic iodine by thyroid, it also reduces the formation of diiodotyrosine and thyroxine.
it is converted to its active form methimazole preventing the thyroid peroxidise enzyme from coupling and iodinating the tyrosine residues on thyroglobulin hence, reducing the production of the thyroid hormones T3 and T4.

It is given orally usually 20-60 mg daily for 4-8 weeks, then reduced gradually to 5-15 mg daily for about 18 months.

CONTRAINDICATION.

Tracheal obstruction
Lactation
Pregnancy
Sign of blood disorder such as sore throat, fever and rashes.

ADVERSE EFFECTS.

Rashes
Blood disorders
Althralgia
Alopecia
Hepatitis
Psychotic reactions.

IODIDES.

POTASSIUM IODIDE: It inhibit the release and synthesis of T3 and T4, it also decreases the vascularity of the hyperplastic gland, it is given by mouth usually 60-180 mg daily.

CONTRAINDICATION.

Hypersensitivity to iodides
Pregnancy
Lactation
Acute bronchitis
Cardiac disease
Addison disease
Children
Renal impairment
Myotonia congenital
Hyperthyroidism.

ADVERSE EFFECTS.

Acneiform rash
Swollen salivary gland
Mucous membrane ulceration
Depression
Insomnia.

RADIOACTIVE IODINE ( 131I ).

It is the only isotope for treatment of thyrotoxicosis, its therapeutic effect depends on the emission of beta rays with an effective half life of 5 days and a penetration range of 0.4-2 mm. It is contraindicated in women in pregnancy or lactation.

BETA ADRENOCEPTOR BLOCKER (PROPRANOLOL).

It is effective in the treatment of thyrotoxicosis, it is most widely studied and used.

It is given by IV injection, at initial a 1 mg (1ml) is injected over one minute, repeated at 2 minute intervals up to a maximum dose of 10 mg in conscious patients or 5mg in anaesthetised patients.

It is contraindicated in uncontrolled heart failure, (cardiogenic shock, metabolic acidosis, marked bradycardia, prinzmetal angina, hypotension, hypersensitivity reactions).