Key Endocrine System Disorders

Why This Matters

The endocrine system operates through intricate feedback loops that maintain homeostasis—and when these loops malfunction, the clinical consequences cascade throughout the body. You're being tested on your ability to recognize why hormone imbalances occur (autoimmune destruction, tumors, feedback disruption, receptor resistance) and how they manifest in predictable symptom patterns. Understanding the underlying pathophysiology transforms a list of random symptoms into a logical clinical picture you can assess, anticipate, and manage.

These disorders appear repeatedly in nursing exams because they demand critical thinking: distinguishing hyper- from hypo- states, recognizing life-threatening complications like adrenal crisis or hypoglycemia, and understanding why specific treatments work. Don't just memorize symptoms—know which feedback mechanism is broken, what hormone is affected, and how nursing interventions restore balance.

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Glucose Regulation Disorders

The pancreas regulates blood glucose through insulin secretion, and disruption of this system—whether through autoimmune destruction or cellular resistance—creates the most common endocrine disorders you'll encounter. Insulin enables glucose uptake into cells; without it, glucose accumulates in the blood while cells starve.

Diabetes Mellitus Type 1

• Autoimmune destruction of pancreatic beta cells—results in absolute insulin deficiency requiring lifelong exogenous insulin
• Hyperglycemia develops rapidly, often presenting with the classic triad: polyuria, polydipsia, and polyphagia
• Diabetic ketoacidosis (DKA) is a life-threatening complication unique to Type 1, caused by fat breakdown producing ketone bodies

Diabetes Mellitus Type 2

• Insulin resistance at the cellular level—the pancreas produces insulin, but target cells don't respond effectively
• Strong association with obesity and metabolic syndrome, making lifestyle modification a first-line intervention
• Hyperosmolar hyperglycemic state (HHS) is the acute complication to monitor for—extreme hyperglycemia without significant ketosis

Diabetes Insipidus

• Unrelated to blood glucose—this disorder involves antidiuretic hormone (ADH) deficiency or resistance, not insulin
• Massive dilute urine output (polyuria) and intense thirst distinguish it from diabetes mellitus; serum glucose remains normal
• Central type responds to desmopressin (synthetic ADH); nephrogenic type requires treating the underlying renal cause

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Thyroid Dysfunction

The thyroid gland regulates metabolic rate through $T_3$ and $T_4$ hormones, controlled by the hypothalamic-pituitary-thyroid axis. Think of thyroid hormones as your body's thermostat—too much speeds everything up, too little slows everything down.

Hypothyroidism

• Decreased $T_3$ and $T_4$ production causes a hypometabolic state—everything slows down, from heart rate to bowel motility
• Hashimoto's thyroiditis is the most common cause in developed countries, an autoimmune condition destroying thyroid tissue
• Levothyroxine replacement is lifelong therapy; monitor for myxedema coma in severe untreated cases

Hyperthyroidism

• Excess thyroid hormone production creates a hypermetabolic state with weight loss despite increased appetite
• Graves' disease is the most common cause—autoantibodies stimulate TSH receptors, often presenting with exophthalmos
• Thyroid storm is the critical complication: extreme tachycardia, hyperthermia, and altered mental status requiring emergency intervention

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Adrenal Cortex Disorders

The adrenal cortex produces cortisol (glucocorticoid) and aldosterone (mineralocorticoid), essential for stress response, metabolism, and fluid balance. Cortisol excess and deficiency create mirror-image clinical pictures—learn one, and you understand both.

Cushing's Syndrome

• Chronic cortisol excess from endogenous overproduction or exogenous corticosteroid use—iatrogenic causes are most common
• Classic presentation includes central obesity, moon facies, buffalo hump, purple striae, and thin fragile skin
• Metabolic complications include hyperglycemia, hypertension, and osteoporosis; assess for infection risk due to immunosuppression

Addison's Disease

• Primary adrenal insufficiency with deficient cortisol and aldosterone production—often from autoimmune adrenal destruction
• Hyperpigmentation is a key distinguishing feature, caused by elevated ACTH stimulating melanocytes
• Adrenal crisis is life-threatening: severe hypotension, hyponatremia, hyperkalemia—requires immediate IV hydrocortisone

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Parathyroid and Calcium Regulation

The parathyroid glands maintain calcium homeostasis through parathyroid hormone (PTH), which raises serum calcium by stimulating bone resorption, increasing renal calcium reabsorption, and activating vitamin D. Calcium imbalances affect neuromuscular function—too high causes weakness, too low causes tetany.

Hyperparathyroidism

• Elevated PTH causes hypercalcemia—remember "bones, stones, groans, and moans" (bone pain, kidney stones, abdominal pain, psychiatric symptoms)
• Primary hyperparathyroidism usually results from a benign parathyroid adenoma secreting PTH autonomously
• Surgical parathyroidectomy is definitive treatment; monitor for hungry bone syndrome postoperatively as calcium rapidly deposits into bones

Hypoparathyroidism

• Insufficient PTH causes hypocalcemia—most commonly iatrogenic from thyroid or parathyroid surgery
• Neuromuscular irritability manifests as muscle cramps, paresthesias, and potentially seizures or laryngospasm
• Chvostek's and Trousseau's signs are classic assessment findings; treatment requires calcium and vitamin D supplementation

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Pituitary Disorders

The pituitary gland is the "master gland," secreting hormones that regulate other endocrine organs. Pituitary tumors typically cause problems through hormone hypersecretion or mass effect compressing nearby structures.

Acromegaly

• Excess growth hormone (GH) in adults causes soft tissue and bone overgrowth—usually from a pituitary adenoma
• Gradual onset with enlarged hands, feet, and facial features; patients often notice rings and shoes no longer fit
• Systemic complications include diabetes, hypertension, cardiomegaly, and sleep apnea; transsphenoidal surgery is first-line treatment

Hyperprolactinemia

• Elevated prolactin most commonly from prolactinomas (pituitary tumors) or dopamine-blocking medications
• Galactorrhea and menstrual irregularities in women; decreased libido and gynecomastia in men
• Dopamine agonists (cabergoline, bromocriptine) are first-line treatment—dopamine normally inhibits prolactin release

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Quick Reference Table

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Self-Check Questions

1. A patient presents with polyuria and polydipsia but has normal blood glucose levels. Which disorder should you suspect, and what hormone is involved?

2. Compare the clinical presentations of Cushing's syndrome and Addison's disease. What single vital sign finding would most quickly help you differentiate between them?

3. Both Hashimoto's thyroiditis and Graves' disease are autoimmune conditions affecting the thyroid. Why does one cause hypothyroidism and the other hyperthyroidism?

4. A patient develops muscle cramps, facial twitching, and a positive Chvostek's sign 24 hours after thyroidectomy. What complication has occurred, and what is the underlying mechanism?

5. If an exam question describes a patient with weight loss, tachycardia, and heat intolerance who suddenly develops high fever and altered mental status, what emergency condition should you recognize, and what is your priority intervention?