reviewer for medsurg

METABOLIC AND ENDOCRINE DISORDERS

Overview of Endocrine System and Pathophysiology

  • The endocrine system comprises a network of glands responsible for the creation and release of hormones.

  • Hormones are defined as chemical messengers that travel through the bloodstream to control vital functions, including:

    • Metabolism

    • Growth

    • Mood

    • Reproduction

    • Response to stress.

  • The endocrine system works in coordination with the nervous system to maintain body balance, referred to as homeostasis.

Major Organs of the Endocrine System

  • The endocrine system consists of 9 major glands and organs, including:

    • Hypothalamus: Regulates homeostasis and controls:

    • Body temperature

    • Heart rate

    • Blood pressure.

    • Pituitary Gland: Known as the master gland, controlling other glands and affecting body growth and development.

    • Composed of two lobes:

      • Anterior lobe: Secretes growth-related hormones.

      • Posterior lobe: Increases water reabsorption in kidneys.

    • Thyroid Gland: Butterfly-shaped gland regulating metabolism through:

    • Calcitonin

    • Triiodothyronine (T3)

    • Thyroxine (T4).

    • Parathyroid Gland: Essential for calcium absorption through PTH secretion.

    • Thymus: Controls the production of T-cells, crucial for the immune response.

    • Ovaries/Testes: Produce hormones that regulate:

    • Blood circulation

    • Mental vigor

    • Sex drive.

    • Pancreas: Involved in digestion and produces insulin and glucagon for glucose regulation.

    • Adrenal Glands: Produce stress response hormones such as adrenaline and cortisol.

Pathophysiology of Disorders

  • Disruptions in hormone production or signaling can lead to imbalances described as: Hypersecretion (overproduction) or Hyposecretion (underproduction).

  • These imbalances can significantly affect:

    • Metabolism

    • Growth

    • Mood

    • Reproduction.

Endocrine Disorders

Pituitary Gland Disorders

  • Prolactinoma: Benign tumor producing excessive prolactin, most common hormone-producing pituitary tumor.

    • Types:

    • Microprolactinomas: Tumors smaller than 10 mm, predominantly found in females (90%).

    • Macroprolactinomas: Larger than 10 mm, more common in males (60%), tend to cause more symptoms.

    • Causes: Exact cause unknown, often sporadic with rarer genetic links.

    • Signs and Symptoms in Females:

    • Irregular or absent periods (amenorrhea/oligomenorrhea)

    • Infertility

    • Milky nipple discharge (galactorrhea)

    • Painful intercourse due to dryness.

    • Signs and Symptoms in Males:

    • Erectile dysfunction

    • Decreased libido

    • Decreased body/hair

    • Gynecomastia (enlarged breasts)

    • Mass Effect Symptoms (especially with macroprolactinomas):

    • Headaches

    • Vision problems.

    • Diagnosis:

    • Elevated prolactin blood levels

    • MRI for tumor detection.

    • Treatment Options:

    • Medications: Dopamine agonists (e.g., bromocriptine, cabergoline)

    • Surgery: Considered if medication is ineffective or intolerable.

    • Radiation Therapy: Rarely used, reserved for resistant cases.

Hypopituitarism

  • Defined as underproduction of pituitary hormones due to:

    • Isolated pituitary deficiency: Affects one hormone only.

    • Multiple hormone deficiency: Affects two or more hormones.

    • Panhypopituitarism: All hormones are affected.

  • Risk Factors:

    • Head trauma, cancer history, sickle cell anemia, severe blood loss from childbirth (Sheehan syndrome).

  • Symptoms (depend on specific hormone deficiency):

    • Growth Hormone: Short stature in children, fatigue in adults.

    • TSH: Cold intolerance, weight gain, fatigue.

  • Diagnosis:

    • Blood tests for hormone levels and stimulation tests.

  • Management:

    • Hormone replacement therapy, surgery for adenomas, focus on stress management.

Acromegaly/Gigantism

  • Caused by excessive growth hormone (GH) from pituitary adenomas.

  • Acromegaly: Occurs post-growth plate fusion in adults, leading to:

    • Enlarged hands/feet/facial features without increased height.

  • Gigantism: Occurs pre-growth plate closure in children, resulting in extreme height.

  • Management:

    • Primarily through reducing GH and IGF-1 levels, often via surgery or medications.

  • Symptoms: Changes in appearance, joint pains, headaches.

Thyroid Gland Disorders

Hyperthyroidism

  • A condition with excessive thyroid hormone production.

  • Commonly associated with Grave’s disease, an autoimmune disorder.

  • Symptoms:

    • Fast heart rate, weight loss, heat intolerance, and anxiety.

  • Diagnosis: Blood tests showing low TSH, elevated T3 and T4, and antibody tests for grave's disease.

  • Management: Includes medication, radioactive iodine ablation, and surgery.

Hypothyroidism

  • Defined as inadequate thyroid hormone production.

  • Often due to negative autoimmune responses (like Hashimoto’s disease).

  • Symptoms: Fatigue, weight gain, cold sensitivity, mental health issues.

  • Diagnosis: Blood tests measuring TSH and T4 levels, often treated with levothyroxine.

Myxedema Coma

  • A life-threatening complication of severe hypothyroidism.

  • Symptoms include hypothermia, altered mental status, or even coma.

  • Treatment includes intravenous thyroid replacement and supportive measures.

Parathyroid Gland Disorders

Hyperparathyroidism

  • Characterized by excessive parathyroid hormone (PTH) production leading to increased blood calcium levels.

  • Signs/Symptoms: Fatigue, kidney stones, and bone pain.

  • Management includes surgery for adenomas and medications to control symptoms.

Hypoparathyroidism

  • Insufficient PTH leading to low blood calcium levels.

  • Causes include surgical damage and autoimmune issues.

  • Symptoms: Muscle spasms, tingling, and weakness.

Adrenal Gland Disorders

Cushing's Syndrome

  • Caused by high cortisol levels from adrenal tumors or prolonged steroid usage.

  • Symptoms include weight gain, hypertension, and 'moon face'.

  • Management focuses on addressing the underlying cause, whether through surgery, medication, or lifestyle changes.

Addison's Disease

  • Characterized by insufficient production of cortisol and aldosterone.

  • Symptoms include fatigue, weight loss, and hypotension.

  • Treatment typically involves hormone replacement therapy.

Pheochromocytoma

  • A tumor of the adrenal glands that overproduces catecholamines, leading to high blood pressure and other symptoms.

  • Surgical removal is the primary treatment.

Hyperaldosteronism

  • Excessive aldosterone production from adrenal glands.

  • Most often causes high blood pressure and low serum potassium. Treatment includes surgery or medications to manage hypertension and potassium levels.

Pancreatic Disorders

Diabetes Mellitus

  • A chronic metabolic disorder marked by high blood sugar levels.

    • Type 1 Diabetes: An autoimmune condition with destruction of insulin-producing cells.

    • Type 2 Diabetes: Insulin resistance accompanied by impaired secretion.

  • Symptoms: Increased thirst, frequent urination, fatigue, and blurred vision.

  • Management involves diet, exercise, blood sugar monitoring, and medications.

Hyperglycemia and Hypoglycemia

  • Hyperglycemia: Elevated blood sugar often caused by inadequate insulin; symptoms include extreme thirst and frequent urination.

  • Hypoglycemia: Low blood sugar can trigger symptoms like shakiness and confusion; immediate treatment with fast-acting sugar is critical.

Pancreatitis

  • Inflammation of the pancreas that can be acute or chronic, with various causes, including gallstones and excessive alcohol intake. Symptoms range from abdominal pain to fever and nausea; management typically includes hospitalization for severe cases.