Essentials in Brief: Hyperthyroidism

Definition: Hyperthyroidism is a condition characterized by the excessive production of thyroid hormones (fT3 and fT4) with suppressed or decreased TSH levels.

Key Symptoms:

• Metabolic Symptoms: Weight loss despite increased appetite, frequent bowel movements, or diarrhea.
• Neurological Symptoms: Inner restlessness, tremors, insomnia.
• Cardiac Symptoms: Rapid pulse, arrhythmias, palpitations, occasionally atrial fibrillation.
• Other Signs: Sweating, clammy hands, reduced sensitivity to cold, fatigue, and menstrual irregularities.

Common Causes:

1. Iatrogenic Hyperthyroidism: Overdose of thyroid hormones.
2. Graves’ Disease (M. Basedow):
   • Autoimmune condition with TSH receptor antibodies.
   • Often accompanied by eye involvement (exophthalmos).
3. Autonomous Adenomas: Overactive nodules producing excess hormones.
4. Thyroiditis (e.g., subacute or Hashimoto’s):
   • Temporary hyperthyroidism due to hormone release from inflamed thyroid tissue.
5. Rare Causes:
   • Secondary hyperthyroidism from excess TSH production.
   • Thyroid hormone receptor resistance (elevated TSH, fT3, fT4).

Diagnosis:

• Laboratory Tests: Elevated fT3/fT4, suppressed TSH.
• Ultrasound: Visualizes structural changes (e.g., nodules, hypervascularity).
• Antibody Tests: Detect autoimmune markers (e.g., TPO antibodies, TSH receptor antibodies).
• Scintigraphy: For assessing hot/cold nodules or confirming overactive areas.

Management:

1. Mild/Temporary Hyperthyroidism:
   • Often self-limiting in cases of thyroiditis.
   • Symptom relief with beta-blockers (e.g., propranolol) to reduce heart rate and fT3 levels.
2. Graves’ Disease or Persistent Hyperthyroidism:
   • Antithyroid Medications: Methimazole, propylthiouracil.
   • Radioiodine Therapy: To reduce thyroid activity.
   • Surgery: For severe or refractory cases.
3. Lifestyle Adjustments: Regular monitoring and stress management.

Complications:

Untreated hyperthyroidism can lead to osteoporosis, severe arrhythmias, and thyroid storm (life-threatening hyperthyroid crisis).

Hyperthyroidism requires a tailored approach depending on the cause and severity, emphasizing early diagnosis and management.

Hyperthyroidism is characterized by elevated levels of fT3 and fT4 and decreased or suppressed TSH. Symptoms of hyperthyroidism include inner restlessness, tremors (notable tremor), insomnia, frequent bowel movements or diarrhea, weight loss despite increased appetite, rapid pulse, arrhythmias with extrasystoles, and occasionally atrial fibrillation. Additional symptoms may include sweating, clammy hands, reduced sensitivity to cold, weakness, and menstrual irregularities. If hyperthyroidism persists, it can lead to osteoporosis.

The most common cause is iatrogenic hyperthyroidism due to an excessive dosage of thyroid hormones. Other causes include autonomous adenomas, early stages of Hashimoto’s thyroiditis, subacute thyroiditis, Graves’ disease (M. Basedow), and diffuse autonomy. Secondary hyperthyroidism, caused by excessive TSH production from the pituitary gland, is rare. Another rare condition is thyroid hormone receptor resistance, in which TSH, fT3, and fT4 may all be elevated.

Autonomous adenomas have already been discussed in the section on nodular goiter. In Hashimoto’s thyroiditis or subacute thyroiditis, an initial phase of hyperthyroidism may occur due to the release of thyroid hormones from thyroid cells damaged by inflammation. In such cases, hyperthyroidism is typically mild and self-limiting. Treatment with antithyroid drugs is not required and would also be ineffective. For pronounced symptoms, the beta-blocker propranolol can be used. Propranolol reduces the conversion of fT4 to fT3, thereby lowering the concentration of the active hormone fT3 and reducing its effects.