Endocrine System and Thyroid Hormones Quiz

Endocrine System Overview

• Thyroid gland is not palpable.
• Thyroid hormones are produced by the thyroid gland.
• Main thyroid hormones: Triiodothyronine (T3) and Thyroxine (T4).
• Thyroid hormone regulates metabolism, heart rate, and supports growth and brain maturation.
• Signs of thyroid disease primarily affect metabolism and cardiac function.
• Iodine is essential for thyroid hormone production.

Hyperthyroidism

• Most common cause is Graves’ disease, an autoimmune disorder.
• Pathophysiology involves immunoglobulins stimulating thyroid hormone synthesis via TSH receptors.
• Exophthalmos is characterized by bulging eyes due to fluid accumulation in tissues.
• Symptoms include weight loss, diarrhea, heat intolerance, anxiety, sweating, tachycardia, and exophthalmos.
• Treatment options include thyroidectomy and radioactive iodine.
• Methimazole (Tapazole) is a prototype medication.
• It inhibits the synthesis of thyroid hormones in the thyroid gland.
• Clinical effectiveness of Methimazole is monitored by a decrease in hyperthyroid symptoms.
• Risks of overtreatment include extreme hypothyroidism, fever, rash, and leukopenia due to agranulocytosis.
• Agranulocytosis is a severe drop in granulocyte count, increasing infection risk.
• Regular CBC and liver function tests are necessary due to Methimazole's potential hepatotoxicity.

Jaundice

• Jaundice is a sign of hepatic failure, marked by elevated bilirubin leading to yellowing of the skin and eyes.
• Always assess the sclera for signs of jaundice.

Hypothyroidism

• Most common cause is Hashimoto’s thyroiditis, an autoimmune condition.
• Pathophysiology involves fibrotic tissue formation due to antibody attacks on the thyroid, leading to decreased hormone production.
• Treatment involves Levothyroxine (Synthroid), a synthetic T4 hormone.
• Levothyroxine is administered PO or IV, converting to T3 in the body.
• Effectiveness is indicated by an increase in metabolic rate.
• Side effects include tachycardia, palpitations, and anxiety; report any signs of hyperthyroidism.

Diabetes Insipidus (DI)

• Symptomatic support focuses on alleviating symptoms rather than treating underlying causes.
• Examples include pain management, fever reduction, and treating respiratory symptoms.
• Beta blockers or antihypertensives may address hyperthyroid symptoms.
• Antidiuretic hormone (ADH) is also known as vasopressin, promoting water retention in kidneys.
• Diabetes refers to excessive urination; Diabetes Insipidus is characterized by low ADH.
• Syndrome of Inappropriate Antidiuretic Hormone (SIADH) involves high ADH levels and fluid retention.
• DI results in dilute urine and low specific gravity. Common causes include pituitary damage.
• Treatment for DI includes Desmopressin Acetate (DDAVP), administered through various routes (nasal, SubQ, IV).
• Desmopressin increases urine concentration by enhancing water reabsorption in renal ducts.
• Hyponatremia symptoms include altered mental status and seizures.

Adrenal Function and Disorders

• The adrenal cortex produces mineralocorticoids (Aldosterone) and glucocorticoids (Cortisol).
• Aldosterone promotes sodium reabsorption and potassium secretion.
• Cortisol provides energy during stress.
• Spironolactone acts as an aldosterone antagonist, leading to sodium excretion while retaining potassium.
• Spironolactone doses vary: typically 50-100 mg for hypertension and 200-400 mg for anti-androgen effects.
• Main side effect of spironolactone: Hyperkalemia (high potassium levels).
• Addison’s disease results in low aldosterone and cortisol, mainly caused by autoimmune destruction.
• Treatment includes long-term steroids like hydrocortisone, which increases both hormones.
• Cushing’s Syndrome arises from excessive cortisol and aldosterone, often due to adrenal hypersecretion or steroid use.
• Treatment for Cushing’s involves reducing steroid use, surgical intervention, and symptomatic support.
• Symptoms of Addison’s include fatigue, dehydration, and hypotension; an adrenal crisis can lead to vascular collapse and renal shutdown.
• Cushing's symptoms include personality changes, moon facies, and purple striae.
• Education on steroids emphasizes the need for gradual tapering to prevent withdrawal effects and stress management.

Steroid Management

• Steroids serve multiple purposes, from inflammation management to treating autoimmune conditions.
• Common steroid suffix: -sone (e.g., prednisone, dexamethasone).
• When taking steroids, timing related to meals is advised based on gastrointestinal tolerance or absorption issues.
• Potential side effects include hypertension, immunosuppression, mood changes, and weight gain.