Thyroid: small gland, big role

Thyroid plays an important role in our body. Proper diet and lifestyle will help its optimum functioning

woman examining her neckThe thyroid is a small gland located below the skin and muscles at the front of the neck, just at the spot where a bow tie would rest. It's brownish red, with left and right halves [called lobes] that look like a butterfly's wings.

The thyroid gland has an important role in the body. It regulates the proper functioning of other organs as well as controls physical and mental growth. Thyroid gland produces two related hormones: thyroxine [T4] and triiodothyronine [T3]. Calcitonin is an additional hormone produced by the thyroid that regulates blood calcium.

Iodine is very important for the synthesis of thyroid hormones by the gland. Hence, any deficiency in intake of iodine not only leads to maternal hypothyroidism, but also mental retardation in the child.Excess of thyroid hormone in the blood is called hyperthyroidism, while its deficit is called hypothyroidism. The secretion of thyroid hormones is regulated by the brain by Thyroid Stimulating Hormone [TSH]. Hence, it can be used for diagnosis of hyperthyroidism [low TSH] and hypothyroidism [high TSH].

Although these are two different conditions, in both hypothyroidism and hyperthyroidism, the thyroid can become larger than normal. An enlarged thyroid gland is a lump that can be felt under the skin at the front of the neck. When it is large enough to see easily, it's called a goiter.

Hypothyroidism[insufficient production of thyroid hormone]

Autoimmune hypothyroidism is a group of disorders characterised by immune-mediated destruction of the thyroid gland. It is influenced by environmental and genetic factors and is four times more common in women than in men.

Symptoms of hypothyroidism include tiredness, weakness, dry skin, feeling cold, hair loss, difficulty in concentrating and memory loss, constipation, weight gain with poor appetite, dyspnoea [breathlessness], coarse voice, menorrhagia [late menopause], Paresthesia [a sensation of tingling, pricking, or numbness], impaired hearing and cardiac rhythm disturbances.

Investigations like blood levels of free T3, T4 and TSH levels, thyroid peroxidase antibodies, biopsy, and ultrasonography of neck may be required for proper diagnosis and management.

Myxedema coma is an important complication of hypothyroidism requiring intensive care and management. Clinical manifestations include reduced level of consciousness, and seizures.There may be a drop in body temperature [hypothermia] to 74 oF. [normal 980F]. Myxedema coma occurs in elderly and is usually precipitated by pneumonia, congestive heart failure, heart attack, and brain haemorrhage.

Hyperthyroidism [Thyrotoxicosis][overactive thyroid gland]

It occurs in two per cent women generally between 20 – 50 years of age; and is only one-tenth as frequent in men. Environmental factors like stress and smoking lead to it via neuro-endocrine effects on immune system; while genetic factors play dominant role in pathogenesis of Grave's disease. Grave's disease is the most common cause of hyperthyroidism.

Emotional instability with hyperactivity, nervousness, and irritability leads to early fatigability. Insomnia and impaired concentration are common. Along with emotional disturbances, cardiac rhythm disturbances are also common. Sweating, intolerance to heat, diffuse hyper pigmentation, and diffuse alopecia are important cosmetic manifestations.

Grave's opthalmopathy are eye manifestations of the disease, which gives a staring look to the patient due to lid retraction. Thyroid dermopathy [skin condition] manifests as plaque on lateral aspect of leg while thyroid acropachy [abnormal growth or swelling of bones] refers to swelling of fingers.The cause of excess thyroid hormone may not be always limited to thyroid gland. Sometimes doctors may have to find other causes of thyrotoxicosis such as carcinomas at different locations like pituitary adenoma, ectopic thyroid or iodine excess.

Treatment options

Medicines: Propranolol and thiourea drugs are used for mild symptomatic thyrotoxicosis. Iodinated contrast agents provide effective temporary treatment for thyrotoxicosis of any cause.

Radioactive iodine: It is an excellent method of destroying overactive thyroid tissue like diffuse or toxic goiter. However, it is not recommended for pregnant women.

Thyroid surgery: Surgical removal of excess thyroid gland is usually preferred for pregnant women, when their thyrotoxicosis is not controlled with low doses of thiourea drugs and also for patients with particularly large goiter and malignant goiter. It is a short surgery with only a day's observation.

Thyroid Crisis or Storm: It is a rare and extreme form of thyrotoxicosis that may occur with stressful illness, thyroid surgery, or radioactive iodine treatment. It is manifested by marked delirium, severe tachycardia, vomiting, diarrhoea, dehydration and high fever.

Pregnancy and thyroid

Since the hormone [hCG] secreted by the placenta is similar to TSH, there are chances of mild hyperthyroidism during first four months of pregnancy. However, hyperthyroidism due to Grave's disease during pregnancy becomes difficult to diagnose. Hence, free T3, free T 4 and TSH levels are important with hCG levels.

Thyroiditis

It is the inflammation of thyroid gland leading to swelling, pain and pressure symptoms [most common is Hashimoto's Thyroiditis]. It is familial and is six times more common in women than in men. The thyroid gland is diffusely enlarged, leading to neck tightness. This also shows symptoms of hypothyroidism like depression, chronic fatigue, dry mouth, and dry eyes.

Treatment of thyroiditis includes antibiotics, thyroid hormone supplementation and supportive care.

Goiter

Palpable enlargement of the thyroid, which may be diffuse or nodular is called Goiter. Although most patients with goiter are euthyroid [normal level], there is high incidence of hypothyroidism or hyperthyroidism.

Diffuse multinodular goiter is caused by numerous conditions like iodine deficiency, pregnancy [in areas of iodine deficiency], Grave's disease, Hashimoto's Thyroiditis, and infections. Blood investigations, biopsy of thyroid gland, ultrasonography of neck is generally required for proper diagnosis and treatment.

Thyroid cancer

Various cancers of thyroid gland are three times common in females as compared to males. The average age range remains 40 – 50 years .These cancers are of various types like papillary, follicular, medullary and anaplastic and appear as a palpable, firm, painless nodule. Flushing, diarrhoea, fatigue, hoarse voice are other symptoms.

Biopsy of thyroid gland, PCR tests, Radioiodine whole body scanning, SPECT and other studies are required to determine type of carcinoma and its spread to other organs of the body.

Treatment options

  • Surgical removal is the treatment of choice for thyroid carcinomas.
  • Patients who have had a thyroidectomy require life-long thyroid hormone supplementation.
  • Radiation therapy is required for bone or brain metastases.

Endocrinologists and physicians [Internal Medicine] are the best to treat thyroid disorders and related complications.

With inputs from Dr Sushil Gadekar, ICU, Fortis Hiranandani Hopsital, Mumbai

Mood Swings

sad womanThyroid disease can affect a person's mood—primarily causing either anxiety or depression. Generally, the more severe the thyroid disease, the more frequent the mood changes.A person who has overactive thyroid [hyperthyroidism] may experience unusual nervousness, restlessness, anxiety and irritability. On the opposite end of the spectrum, a person who has underactive thyroid [hypothyroidism] may experience mild to severe fatigue and depression.

— Team CW

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