Hyperthyroidism Signs Symptoms Causes Treatment Medication

What is Hyperthyroidism?

Thyroid normally has a self-control mechanism, which is also known as "feed back mechanism". However, sometimes this control mechanism fails and the production of the hormones is more than the requirement. This clinical condition is called hyperthyroidism. The excess of thyroid hormones result in certain signs and symptoms of increased metabolic activity. In such patients, the levels of FT3 and FT4 are above normal values and the TSH levels drop (exactly opposite to hypothyroidism).

Causes of Hyperthyroidism All patients with Hypothyroidism may not have the same cause, but majority have an unnatural stimulus by a TSH like substance, which is an antibody against TSH receptor on the thyroid. Such stimulation may be in the entire thyroid gland or in part of it. The increased output of the hormones from the thyroid produces some or all of the symptoms associated with hyperthyroidism. Grave's disease

What causes sudden hyperthyroidism?

An autoimmune disorder is the most common cause of hyperthyroidism. Instead of TSH, antibodies against the TSH receptors, bind to and stimulate the thyroid gland, leading to continuous and uncontrolled production of thyroid hormones.

Signs and symptoms of Hyperthyroidism
Palpitations
Heat intolerance
Nervousness
Irritability
Excessive appetite
Insomnia
Breathlessness
Increased bowel movement
Scanty menstrual periods or their absence
Fatigue
Increased heart rate
Trembling hands
Weight loss
Weakness
Warm and moist skin
Hair loss
Staring gaze

Hyperthyroidism and Thyrotoxicosis: Are they same?

No. When blood thyroid hormone levels are in excess, either due to a drug (e.g. excess of Thyroxine supplements) or disease (Thyroiditis) or hyperthyroidism, such condition is called as thyrotoxicosis. Thus, thyro- toxicosis is a term which defines higher levels of thyroid hormones be whatever the cause; whereas hyperthyroidism refers to over functioning of the thyroid gland. This knowledge is essential because a patient with thyrotoxicosis but without hyperthyroidism should not be treated for the latter.

Hyperthyroidism and Thyroiditis: Are they related?

Thyroiditis is an inflammation of the thyroid gland due to autoimmunity, which partially or completely des- troys the functioning of the gland. During the phase of active inflammation, thyroid cells are destroyed and hence release the stored thyroid hormones (triiodothyronine (T3) and T4). The T3 and T4 (thyroxine) levels may remain raised for days or months. This elevation in the hormone levels can be confused and misdiagnosed as hyperthyroidism. It is essential to rule out thyroiditis in all patients with thyrotoxicosis with the help of Pathology Test before starting any specific therapy.

Since thyroiditis is an autoimmune disorder, the patient will have circulating antibodies, mainly against the thyroid specific protein, thyroglobulin (anti-thyroglobulin antibodies or ATG) and microsomal antigen (anti-microsomal antibodies or AMA). AMA are also known as anti-thyroid peroxidase antibodies. Though it is not confirmatory, the presence of both these antibodies in the patient's blood can alert the physician to be cautious before instituting therapy for hyperthyroidism.

Thyroid uptake test using radioiodine or another suitable radioisotope has to be done. High levels of uptake by the gland indicate hyperthyroidism and treatment for this condition should be started.

Treatment modalities for hyperthyroidism

1. Drug therapy
2. Radioiodine therapy
3. Surgery
Either one or a combination of the above three modalities are given, as treatment for patients with hyperthyroidism. Each of these has its own advantage and limitation, with individual physicians preferring one to the other, due to reasons of simplicity, cost and availability and also considering severity of hyperthyroidism, existing illness and the patient's age. The symptoms of hyperthyroidism may be rapidly relieved by betablockers. These medications counteract the increased metabolic effect of thyroid hormones, without altering their levels.

Anti-Thyroid Drugs (ATDs) Anti-Thyroid Drugs block the production of thyroid hormones and are used to bring back thyronormalcy. These drugs include thioamides like Propylthiouracil (PTU) or Neomercazole or Methimazole which are believed to be immunomodulatory also. PTU is preferred in pregnant hyperthyroid patients. For majority of Thyroidologists, ATDs are the first choice of therapy due to their availability and one can stop medication at any time desired. The dose and duration of Anti-Thyroid Drugs is based on the age and severity of hyperactivity and the cause of hyperthyroidism.

What is Radioiodine therapy

Not all cases of hyperthyroidism are easily controlled by ATDs and here radioiodine therapy becomes a better choice. Iodine-131 is a radioactive isotope of iodine. Because of its isotopic nature, it is unstable as an atom and releases gamma and beta rays. These when come in contact with cells, cause reactions within and destroy it. The degree of destruction depends on the amount of radioisotope given. Small amounts destroy lesser amount of cells. The body can recover the loss of cells to a certain extent. Large quantities of radioisotope are required for the treatment of thyroid cancer as they are useful to destroy cancer cells .

In radiolodine therapy, depending upon the extent of thyroid gland destruction, the amount of the same is administered. For hyperthyroidism where one is interested in partial destruction of the gland, smaller doses such as 5-10mCi is given. It is like doing a surgery and removing a part of the gland without cutting open the patient and avoiding anesthesia.

In case of thyroid cancer, where the whole thyroid has to be destroyed, radioiodine in larger doses of more than 50mCi are given along with surgery. This helps in complete removal of cancerous cells which may have been left behind after surgery.

Radioiodine therapy is simple and also cheap. However, since only nuclear medicine professionals do the handling, non-nuclear medicine thyroidologists give less importance to radioiodine treatment. There is a misconception in the minds of the patients and many physicians that radioiodine treatment is very harmful. Radioiodine is contraindicated in pregnancy and during breastfeeding .

Surgery Where radioiodine treatment is not available and the patient does not respond to ATDs, a partial thyroidectomy may be an option. However, thyroid surgery is done under general anesthesia and the surgery is costly. If along with hyperthyroidism, the patient has a solitary or multinodular goiter, surgery is preferred. This mode of treatment requires 5 to 7 days of hospitalisation.

Every patient will need proper evaluation before selecting treatment. No treatment mode can be said to be the best for every patient of hyperthyroidism. Since physicians have their individual preferences, all the three are widely used. Many thyroidologists are of the opinion that, if available, radioiodine is the best.

Management & monitoring of hyperthyroidism in patients

Every patient may not respond well to ATDs and a decision has to be made for alternate treatment, keeping in mind what is ideal for the patient, its cost and availability. And hence the management of hyperthyroidism is crucial. The conventional laboratory tests T3, T4 and TSH often yield results that are difficult to comprehend. In these patients, since the intact hypothalamus pituitary thyroid axis is disturbed, it requires expertise to fine tune the dosage to avoid either unwanted therapy or under treatment. Many thyroidologists use TSH, FT3 and FT4 combinations to get a correct picture of the thyroid status.

The conditions can be analysed by evaluating the levels of thyroid hormones. Once diagnosed, these abnormal conditions can be brought to perfect normalcy with the help of proper medication within few weeks or months.