HYPERTHYROIDISM

HYPERTHYROIDISM Hyperthyroidism is a condition caused by an excess of circulating thyroid hormones (T4, T3 and Calcitonin) in the body. WHO IS MORE PRONE? In hyperthyroidism, women are 8x more affected than men, with onset usually between the second and fourth decades. RISK FACTORS: Emotional Stress/Shock or Chronic Stress - STRESS causes the adrenal glands to secrete its hormones (catecholamines) and too much catecholamines disrupt the regulatory control of thyroid gland. High Iodine Diet - Too much IODINE in diet would cause the thyroid gland to speed up its activity. Overtreatment with Thyroid Drugs - There will be loss of thyroid's regulatory control due to excessive hormone medications received. Thyroid Cancer - Cancer cells, just like stress, disrupts the thyroid's regulatory control. Autoimmune - Hyperthyroidism may also be caused by the body's own immune system. GRAVE'S DISEASE, the most common type of hyperthyroidism, results from an excessive circulating thyroid hormones due to abnormal stimulation of the thyroid gland by circulating immunoglobulins (autoimmune). THYROID HORMONES: ✓ T4 - Thyroxine = responsible for ↑ or ↓ body heat production ✓ T3 - Triiodothyronine = responsible for ↑ or ↓ metabolic rate ✓ Calcitonin = responsible for ↑ calcium in the bones & ↓ calcium in the blood PATHOPHYSIOLOGY: In HYPERTHYROIDISM, all thyroid hormones are excessively produced. First, there is increased T4 production. This leads to increase in our own body's capability to produce heat. Therefore, individuals with hyperthyroidism are considered "Heat intolerant." This description rooted from the person's inability to tolerate heat due to having high body heat production. Second, there is increased T3 production. This leads to increase in the metabolic rate. Metabolic rate is the overall rate of all bodily processes such as energy expenditure. Therefore, there will be weakness and fatigue due to excessive use of energy. This also leads to polyphagia (increased hunger) and weight loss (due to increased metabolism of nutrients ingested). An increase in both T3 and T4 will lead to increase in sympathetic nervous system (SNS) activity and decrease in insulin activity. Vital signs, such as heart rate, respiration and blood pressure will increase. Amenorrhea may also be present in women. Decreased insulin activity will lead to increase in blood glucose. Restlessness, agitation and nervousness are also evident due to increase in central nervous system (CNS) activity. Lastly, there is increased Calcitonin production. This results to low calcium in blood leading to increased cell membrane permeability and neuromuscular irritability. Increased neuromuscular irritability results to fine tremors and increased peristalsis (diarrhea). GRAVE'S DISEASE An autoimmune disease characterized by: (1) Hypothyroidism; (2) Exophthalmos (protrusion of the eyeballs); and (3) Diffuse goiter (due to abnormal stimulation of thyroid gland). If hyperthyroidism has an autoimmune origin, inflammation may be present especially in the eyes and skin. In the eyes, there would be build-up of fluids (edema) at the extraocular muscles. This leads to increase in the orbital soft tissue volume. Increased orbital soft tissue volumes causes the eyelid opening to widen (leading to Dalyrimple's sign - a direct outward stare & Stellwag's sign - rare blinking), the eyeballs to be pushed forward (leading to Exophthalmos - bulging eyes), the fatpads above eyes to increase (leading to Jeffrey's sign - smooth forehead upon looking up) and weakening of the extraocular muscles (leading to Von Graefe's sign - lagging of upper eyelid on downward eye rotation & Rosenbach's sign - fine tremors of the eyelids). In the skin, inflammation is also attributed to pretibial myxedema. This is a dermopathy that causes the skin to feel like an orange peel. This condition is also frequently accompanied with warm flushed skin and diaphoresis.