Lekcja 7: Kliniczne aspekty chorób układu hormonalnego 2 | Clinical Aspects of Endocrine Diseases 2

Hyperthyroidism

Overview:
Hyperthyroidism is a condition characterized by the excessive production of thyroid hormones (triiodothyronine [T3]and thyroxine [T4]), leading to an accelerated metabolism. The thyroid gland plays a central role in regulating metabolism, heart rate, and body temperature.

Etiology:

  • Graves’ Disease: The most common cause of hyperthyroidism, Graves’ disease is an autoimmune disorder where antibodies (TSI – thyroid-stimulating immunoglobulins) stimulate the thyroid gland to produce excess hormones.
  • Toxic Multinodular Goiter: Involves the presence of multiple nodules in the thyroid that produce thyroid hormones independently of TSH regulation.
  • Thyroiditis: Inflammation of the thyroid gland may temporarily cause hyperthyroidism by releasing stored hormones into the bloodstream.

Pathophysiology:
Excessive levels of T3 and T4 lead to increased metabolic activity in almost all tissues, resulting in an overactive metabolism. The condition also amplifies the body’s sensitivity to catecholamines, further stimulating metabolic processes.

Clinical Manifestations:

  • Weight Loss: Despite increased appetite, patients often experience significant weight loss due to heightened metabolic rates.
  • Tachycardia and Palpitations: A rapid heart rate is common, along with irregular heartbeat (arrhythmia).
  • Heat Intolerance: Patients may feel excessively warm or sweaty, even in cool environments.
  • Exophthalmos (in Graves’ disease): Protrusion of the eyeballs is a hallmark feature due to inflammation and swelling behind the eyes.
  • Anxiety, Tremors, and Hyperactivity: Heightened nervous system activity results in tremors, restlessness, and mood swings.
  • Goiter: The thyroid gland may become enlarged and palpable in cases of Graves’ disease or toxic multinodular goiter.

Diagnosis:

  • TSH Levels: Suppressed levels of thyroid-stimulating hormone (TSH) indicate overactive thyroid function.
  • Free T4 and T3: Elevated levels confirm hyperthyroidism.
  • Radioactive Iodine Uptake Test: Measures the thyroid’s ability to absorb iodine, which can help differentiate between Graves’ disease, thyroiditis, and toxic nodular goiter.

Management:

  • Antithyroid Medications: Methimazole and propylthiouracil (PTU) are commonly used to inhibit thyroid hormone production.
  • Radioactive Iodine Therapy: This treatment involves the oral intake of radioactive iodine, which is selectively absorbed by the thyroid gland, gradually destroying overactive thyroid tissue.
  • Beta-Blockers: Used to manage symptoms like tachycardia and tremors while other treatments take effect.
  • Surgery: In severe cases, partial or total thyroidectomy may be required to remove part or all of the thyroid gland.

Hypothyroidism

Overview:
Hypothyroidism occurs when the thyroid gland is unable to produce sufficient levels of thyroid hormones, leading to a slowed metabolism. The condition is more common in women, especially those over the age of 60, and can develop due to a variety of causes.

Etiology:

  • Hashimoto’s Thyroiditis: An autoimmune disorder where the immune system attacks the thyroid gland, leading to chronic inflammation and reduced hormone production.
  • Iodine Deficiency: Iodine is essential for the production of thyroid hormones. A deficiency in iodine intake can lead to hypothyroidism.
  • Post-Thyroidectomy or Radioactive Iodine Treatment: Patients who have undergone thyroid surgery or radioactive iodine treatment for hyperthyroidism may develop hypothyroidism.

Pathophysiology:
The deficiency of T3 and T4 hormones slows down the body’s metabolic processes, resulting in reduced energy production, sluggish organ function, and impaired growth and development in children.

Clinical Manifestations:

  • Fatigue and Weakness: Patients often feel chronically tired and lethargic.
  • Weight Gain: Despite a decreased appetite, weight gain is common due to reduced metabolic rates.
  • Cold Intolerance: Patients may feel unusually cold even in warm environments.
  • Dry Skin and Hair: Hypothyroidism often results in dry, coarse skin and brittle hair.
  • Bradycardia: A slower-than-normal heart rate can occur due to reduced thyroid hormone activity on the heart.
  • Constipation: A sluggish digestive system is a common symptom.
  • Depression and Memory Problems: Cognitive impairments, including difficulty concentrating and memory loss, can also manifest.

Diagnosis:

  • TSH Levels: Elevated TSH is the hallmark of primary hypothyroidism, as the pituitary gland produces more TSH to stimulate the underactive thyroid.
  • Free T4: Decreased levels of free T4 confirm the diagnosis of hypothyroidism.
  • Thyroid Antibodies: Elevated levels of anti-thyroid peroxidase (TPO) antibodies suggest Hashimoto’s thyroiditis.

Management:

  • Levothyroxine: This synthetic form of thyroxine (T4) is the primary treatment for hypothyroidism. It restores normal hormone levels and alleviates symptoms.
  • Regular Monitoring: TSH and T4 levels must be regularly monitored to adjust the dose of levothyroxine and ensure proper thyroid function.

Addison’s Disease (Adrenal Insufficiency)

Overview:
Addison’s disease is a disorder in which the adrenal glands fail to produce sufficient amounts of cortisol and, in some cases, aldosterone. Cortisol plays a critical role in regulating metabolism, immune response, and stress, while aldosterone controls sodium and potassium balance.

Etiology:

  • Autoimmune Destruction: The most common cause of Addison’s disease is the autoimmune destruction of the adrenal cortex.
  • Infections: Tuberculosis, fungal infections, and HIV can destroy the adrenal glands and lead to adrenal insufficiency.
  • Adrenalectomy: Surgical removal of the adrenal glands for tumor treatment can result in Addison’s disease.

Pathophysiology:
The deficiency of cortisol results in impaired glucose metabolism, reduced energy levels, and diminished stress response. Lack of aldosterone leads to salt wasting, dehydration, and potassium retention, further complicating the condition.

Clinical Manifestations:

  • Fatigue and Weakness: Profound fatigue is a hallmark symptom due to cortisol deficiency.
  • Hyperpigmentation: Increased ACTH levels stimulate melanocytes, causing darkened skin, particularly on the face, neck, and hands.
  • Hypotension and Dizziness: Low levels of aldosterone and cortisol can result in significant drops in blood pressure, leading to dizziness or fainting.
  • Salt Craving: Patients often crave salty foods due to the body’s need for sodium.
  • Weight Loss and Anorexia: Decreased appetite and weight loss are common.
  • Abdominal Pain and GI Distress: Nausea, vomiting, and diarrhea may also occur.

Diagnosis:

  • ACTH Stimulation Test: This test evaluates the adrenal glands’ response to synthetic ACTH. A lack of cortisol production after stimulation indicates adrenal insufficiency.
  • Serum Cortisol and ACTH Levels: Low cortisol levels and high ACTH levels are characteristic of primary Addison’s disease.
  • Electrolyte Imbalances: Low sodium and high potassium levels often accompany Addison’s disease due to aldosterone deficiency.

Management:

  • Hormone Replacement Therapy: Lifelong treatment with oral corticosteroids (e.g., hydrocortisone, prednisone) replaces the missing cortisol. Fludrocortisone is used to replace aldosterone in cases of significant mineralocorticoid deficiency.
  • Management of Adrenal Crisis: In times of stress (e.g., infection, surgery), patients may require higher doses of corticosteroids to prevent adrenal crisis, a life-threatening condition characterized by severe hypotension and shock.
  • Monitoring: Regular monitoring of electrolytes and hormone levels is essential for adjusting therapy and preventing complications.