Hyperthyroidism: Causes, Clinical Features, Diagnosis, and Treatment Explained

Hyperthyroidism: Causes, Clinical Features, Diagnosis, and Treatment Explained

Question. Write a short note on hyperthyroidism.
Or
Question. Describe the clinical findings of hyperthyroidism.
Or
Describe the clinical findings, diagnosis, and management of hyperthyroidism.

Answer. Hyperthyroidism is defined as increased secretion of thyroid hormone with an increase in levels of T3 and T4.

Hyperthyroidism: Causes, Clinical Features, Diagnosis, and Treatment

Etiology Of Hyperthyroidism

Common causes:

• Grave’s disease
• Toxic nodular goiter
• Multinodular
• Solitary nodule

Less common:

• Thyroiditis
• Drug­induced
• Factitious
• Iodine excess

Rare:

• Pituitary or ectopic TSH
• Thyroid carcinoma

Clinical Features Of Hyperthyroidism

• Goiter is present, i.e. either diffuse or nodular.
• Gastrointestinal features: Vomiting, diarrhea, and weight loss
• Cardiovascular features: Arrhythmia, i.e. atrial fibrillation, dyspnea, wide pulse pressure
• Dermatological manifestations: Clubbing, loss of hair, palms becoming red, increased sweating
• Reproductive features: Amenorrhea, infertility, abortion, impotence
• Ophthalmological features: Exophthalmos, Diplopia, lid retraction, staring look, excessive watering from eyes
• Neuromuscular features: Tremors in hand, psychosis, irritability, restlessness, nervousness, high tendon reflexes
• Miscellaneous: Fatigue, polydipsia, heat tolerance

Symptoms and Causes of Hyperthyroidism

Investigations Of Hyperthyroidism

• Serum TSH level is decreased and is the initial diagnostic test. Normal TSH levels exclude clinical hyperthyroidism.
• Serum total and unbound (free) T3 and T4 are increased in hyperthyroidism.
• In some cases, only T3 levels are raised whereas T4 is normal (T3 toxicosis).
• TSH­R antibody levels are increased in about 75% of cases.
  ESR may be increased in subacute thyroiditis.
• The uptake of radioactive iodine by the thyroid is increased in Graves’ disease and toxic nodular goiter, whereas it is low in subacute thyroiditis.
• Ultrasonography of the thyroid gland reveals diffuse enlargement of thyroid gland which helps in diffrentiating
• Graves’ disease from nodular goiter.

Drug Therapy for hyperthyroidism

• Anti-thyroid drugs such as carbimazole, i.e. 40–60 mg/day, methimazole, i.e. 100–150 mg 8 hourly, and propylthiouracil, i.e. 300–450 mg/day can be given depending on the severity of the disease.
  Drugs should be gradually decreased for 4–8 weeks based on FT4 levels.
  When FT4 levels are normal, carbimazole 5–15 mg/day or propylthiouracil 50 mg/day is given.
  Drugs can be given for 1–2 years by regular checking of FT4 and TSH levels.
• For symptomatic relief, beta­blockers such as propranolol 80–160 mg daily is given.
  It is given for 2–3 weeks along with anti-thyroid treatment.
  It relieves symptoms such as anxiety, tremors, and tachycardia.
• Dexamethasone 8 mg/day may be used to inhibit the conversion of T4–T3 in severe forms of thyrotoxicosis.
• Lithium carbonate 300–450 mg TDS inhibits thyroid hormone secretion temporarily in patients who are allergic to iodides and thioamides.
• Potassium perchlorate 500 mg BD inhibits iodine uptake by the thyroid gland. It is combined with thioamides.

Surgery Of Hyperthyroidism

• Subtotal thyroidectomy is done in severely affcted cases. Before surgery, the patient should be made euthyroid by beta­ blockers and anti­thyroid drugs.
• Two weeks before the surgery drugs should be stopped and lugol iodine is given to reduce the vascularity.

Radioactive Iodine Of Hyperthyroidism

• Radioactive iodine, i.e. 131I leads to the destruction of thyroid cells and is given with anti­thyroid drugs to prevent thyroid storm.
• Anti­thyroid drugs must be stopped for a minimum of 3–5 days before 131I to allow uptake of isotope 555MBq to ablate the thyroid.
• High doses are needed for large goiters in severely thyrotoxic patients.

Diagnosis Of Hyperthyroidism

The case with signs like exophthalmos, tremors, tachycardia, and thyroid enlargement and symptoms, i.e. sweating, intolerance to heat, restlessness, increased appetite, diarrhea, and weight loss, can be diagnosed as hyperthyroidism. In an anxiety state, the hands are cold and moist while in hyperthyroidism, they are warm and moist.

• Thyroid function test: There are raised T3 and T4 levels.
• Diagnosis is solely based on investigations.
• Serum TSH level is decreased and is the initial diagnostic test. Normal TSH levels exclude clinical hyperthyroidism.
• Serum total and unbound (free) T3 and T4 are increased in hyperthyroidism.
• In some cases, only T3 levels are raised whereas T4 is normal (T3 toxicosis).
• TSH­R antibody levels are increased in about 75% of cases.
  ESR may be increased in subacute thyroiditis.
• The uptake of radioactive iodine by the thyroid is increased in Graves’ disease and toxic nodular goiter, whereas it is low in subacute thyroiditis.
• Ultrasonography of the thyroid gland reveals diffuse enlargement of the thyroid gland which helps differentiating
• Graves’ disease from nodular goiter.