Thyroid Disorders: Types, Causes, Symptoms and Risk Factors

The thyroid gland produces hormones like triiodothyronine (T3) and thyroxin (T4) which help in normal regulation of metabolism and also influence the control of vital functions, such as body temperature and heart rate. An imbalance of these hormones can have an enormous impact on health and lead to various disorders. The commonest of all thyroid disorders are:

1.HYPOTHYROIDISM

Hypothyroidism is a medical condition in which the thyroid gland doesn’t produce an adequate amount of thyroid hormones.

Causes

• Autoimmune: Hashimoto’s thyroiditis (90%of the cases), spontaneous atrophic hypothyroidism, Graves’s disease.
• Iatrogenic
• Transient thyroiditis
• Congenital disorders like dyshormogenesis or thyroid aplasia
• Benign tumor of the pituitary gland.
• Pregnancy
• Iodine deficiency

Risk factors

Common risk factors are:

• Female: Women are affected about six times more frequently than men.
• Elderly (more than 60 years)
• Family history of thyroid disease
• History of an autoimmune disease (eg. type 1 diabetes or celiac disease)

Clinical features

• Hypothyroidism may be asymptomatic in the early stages. But over time untreated hypothyroidism can lead to numerous health problems such as obesity, joint pain, infertility, and heart disease.

Symptoms

• Cold intolerance (increased sensitivity to cold)
• Weight gain
• Fatigue, somnolence
• Dry skin, dry hair
• Menorrhagia
• Constipation
• Muscle stiffness or pain or swelling in the joints
• Deafness
• Depression or impaired memory
• Alopecia
• Psychosis (myxoedema madness)

Signs

• Facial feature: Puffy face, purplish lips, malar flush, myxoedema(periorbital edema, loss of lateral eyebrows)
• Hoarseness of voice
• Carotenaemia (yellowing of the skin)
• Hypertension
• Slowed heart rate (bradycardia)

2.HYPERTHYROIDISM

Overactive thyroid (Hyperthyroidism) describes a constellation of clinical features arising from elevated circulating levels of thyroid hormone thyroxin. It can accelerate the body’s metabolism, causing unintentional weight loss and a rapid or irregular heartbeat.

Causes

• Graves’ disease
• Nodular goiter (toxic adenoma, toxic multinodular goiter or Plummer’s disease)
• Thyroiditis both subacute (de Quervain’s) or post-partum
• Follicular carcinoma

Risk factors

Risk factors for hyperthyroidism include:

• Family history of Graves’ disease
• Female
• History of chronic diseases like type 1 diabetes, pernicious anemia, and primary adrenal insufficiency

Clinical features

Hyperthyroidism can cause a wide range of signs and symptoms like:

Symptoms

• Weight loss despite normal or increased appetite
• Heat intolerance: Increased sensitivity to heat
• Palpitations: pounding of the heart
• Dyspnea
• Irritability, emotional lability
• Fatigue, muscle weakness
• Tremor: a fine trembling of hands and fingers
• Osteoporosis
• Diarrhea, steatorrhea
• Angina
• Periodic paralysis
• Pruritus
• Alopecia
• Amenorrhea/oligomenorrhoea
• Infertility
• Spontaneous abortion
• Loss of libido, impotence

Signs

• Palmar erythema
• Sinus tachycardia, irregular heartbeat (arrhythmia), atrial fibrillation, cardiac failure
• Lid retraction, lid lag
• Skin thinning with fine, brittle hair
• Proximal myopathy
• Pigmentation
• Gynaecomastia
• Nervousness, anxiety, and irritability
• Sweating

Sometimes hyperthyroidism may be associated with Graves’ ophthalmopathy which causes eyeballs to protrude beyond their normal protective orbits (exophthalmos) and swelling extraocular muscles.

3.THYROID NODULE

Nodules are abnormal masses or lumps that form within the thyroid. Nodules can be caused by benign cysts, tumors or by cancers of the thyroid (rare).

Usually, thyroid nodules are asymptomatic but occasionally some nodules become so large that they can:

• Be seen and palpated as a swelling at the base of your neck
• Press on the trachea or esophagus, causing difficulty swallowing or shortness of breath

4.GOITER

Goiter refers to the enlargement of the thyroid gland. Usually, goiters are painless, although a large goiter can lead to cough and cause difficulty in swallowing or breathing.

Lack of iodine in the diet is the most common cause of goiters worldwide.

Risk factors

Some common risk factors for goiters include:

• A lack of dietary iodine.People living in areas where iodine is a lack of iodine and those who don’t have access to iodine supplements are usually at higher risk of developing goiter.
• Goiters are more common after age 40.

Causes

Some of the most common causes include:

• Iodine deficiency.
• Graves’ disease.
• Hashimoto’s disease.
• Solitary thyroid nodules.
• Thyroid cancer.
• Inflammation.

Symptoms

Usually, goiters are asymptomatic but a large goiter may show the following signs and symptoms:

• Swelling at the base of the neck
• Hoarseness
• Coughing
• Difficulty breathing
• Difficulty swallowing

DIAGNOSIS OF THYROID DISORDERS

• Physical examination: of the thyroid gland to check for enlargement, swelling and checking for tremors and pulse are part basic examination.
• Thyroid profile: to check the levels of triiodothyronine (T3), thyroxin (T4) and TSH.
• Blood tests
• Radioiodine uptake test
• Thyroid scan: a radioactive isotope is injected intravenously and then a scan is done for the thyroid gland.
• Thyroid ultrasound.
• CT Scan and MRI
• Biopsy

TREATMENT

• The daily requirement of iodine is about 150 micrograms. Using iodized salt or eating seafood like sushi about twice a week is helpful. Shrimp and other shellfish also have high iodine content.
• Medications: thyroid hormone replacement therapy like levothyroxine (Levoxyl, Synthroid, and Tirosint) is used in case of hypothyroidism which also decreases the size of the goiter. While in the case of hyperthyroidism, medications to normalize hormone levels are required.
• Surgery: Removing all or part of your thyroid gland (total or partial thyroidectomy) may be necessary.