Lesson 2 Diabetes Insipidus and Syndrome of Inappropriate Diuretic Hormones

Adrenal Cortex Function

Synthesizes glucocorticoids (cortisol) and small amounts of sex hormones; essential for metabolism and stress response

Adrenal Medulla Function

Works as part of sympathetic nervous system; produces epinephrine and norepinephrine for fight-or-flight response

Primary Adrenal Insufficiency Causes

Autoimmune destruction of adrenal cortex, surgical removal, infection; hyposecretion originates IN the adrenal glands (Addison's disease)

Secondary Adrenal Insufficiency Cause

Hyposecretion of ACTH from pituitary gland; problem OUTSIDE adrenals affecting hormone stimulation

Addison Disease Glucocorticoid Loss Effects

Decreased vascular tone, decreased vascular response to catecholamines, decreased gluconeogenesis → hypotension and hypoglycemia

Addison Disease Mineralocorticoid Loss Effects

Loss of aldosterone → sodium and water loss with potassium retention → dehydration, hypotension, hyponatremia, hyperkalemia

Addison Disease Clinical Presentation

Fatigue, N/V/D, anorexia, hypotension, hypovolemia, confusion, hypoglycemia, decreased sodium/water, increased potassium, hyperpigmentation (bronze skin)

Addison Disease Lifelong Requirement

Requires lifelong glucocorticoid replacement therapy; fatal if left untreated; never discontinue steroids abruptly

Cushing Syndrome Definition

Excessive cortisol production; can be iatrogenic (from adrenal cortex), exogenous (prolonged high-dose glucocorticoid administration), or from ACTH tumors

Cushing Disease vs Cushing Syndrome

Cushing DISEASE: specifically caused by excess ACTH from pituitary tumor → increased cortisol; Cushing SYNDROME: broader term for any excess cortisol regardless of cause

Cushing Syndrome Memory Trick

"Couch cushion" - think cushy/padded appearance; central obesity, moon face, buffalo hump from fat redistribution

Cushing Syndrome Classic Appearance

Moon face, buffalo hump, truncal obesity with thin extremities, weight gain, hirsutism (masculine features), fragile skin with easy bruising, purple striae on abdomen/thighs

Cushing Syndrome Electrolyte Pattern

Hypernatremia (sodium retention), hypokalemia (potassium loss), hypocalcemia; opposite of Addison's electrolyte pattern

Cushing Syndrome Metabolic Effects

Hyperglycemia (cortisol raises blood sugar), hypertension (from sodium/water retention), muscle wasting and weakness despite weight gain

Thyroid Gland Hormone Production

Produces T3 (triiodothyronine) and T4 (thyroxine) to control body metabolism and growth, plus calcitonin to lower serum calcium

Primary vs Secondary Hypothyroidism

Primary: thyroid gland dysfunction, cannot produce hormones; Secondary: thyroid not stimulated by pituitary to produce hormones

Hashimoto Thyroiditis Pathophysiology

Autoimmune disorder; immune system produces antibodies that attack thyroid → increased WBCs in thyroid → thyroid damage → insufficient thyroid hormone production → hypothyroidism

Hypothyroidism Clinical Features

Lethargy/fatigue, cold intolerance, weight gain, dry skin/coarse hair, bradycardia, constipation, myxedema (puffiness around eyes/face), forgetfulness, menstrual disturbances, goiter

Hypothyroidism Metabolic State

DECREASED rate of body metabolism; everything slows down (LOW and SLOW - like earlier flashcard memory trick)

Myxedema Coma Definition

Rare, serious, life-threatening complication of persistently low thyroid hormone; medical emergency with high mortality

Myxedema Coma Triggers

Acute illness, rapid withdrawal of thyroid medication, anesthesia/surgery, hypothermia, sedatives

Myxedema Coma Presentation

Severe hypothermia (very low body temp), anemia, heart failure, confusion, coma

Myxedema Coma Priority Interventions

Maintain patent airway, aspiration precautions, IV fluids, IV levothyroxine, IV glucose, corticosteroids, keep patient warm, continuous monitoring

Levothyroxine (Synthroid) Mechanism

Treats hypothyroidism by replacing thyroid hormone; increases metabolic rate, O2 demand, respiration, heart rate, and metabolism of fats/carbs/proteins

Levothyroxine Critical Teaching

Takes up to 8 weeks for full effect; take once daily in morning before breakfast; report hyperthyroidism signs (tachycardia, palpitations, weight loss, insomnia, anxiety); monitor T3/T4 levels

Levothyroxine Side Effects

Anxiety, GI upset, sweating, weight loss, heat intolerance (signs of excessive thyroid hormone - hyperthyroidism symptoms)

Hyperthyroidism Definition

Hypersecretion of thyroid hormones (T3 and T4); INCREASED rate of body metabolism; everything speeds up

Graves Disease

Autoimmune disorder causing overproduction of thyroid hormones; most common cause of hyperthyroidism; more common in women

Hyperthyroidism Lab Pattern

T3 and T4 usually ELEVATED, TSH is LOW (negative feedback: high thyroid hormones suppress TSH)

Hyperthyroidism Clinical Presentation

Irritability, agitation, nervousness, tremors, weakness, heat intolerance, weight loss, smooth soft skin/hair, palpitations, dysrhythmias, diarrhea, diaphoresis, hypertension, goiter

Exophthalmos

Bulging eyes; seen in Graves disease from increased tissue and fat behind eyeballs; classic visual finding in hyperthyroidism

Thyroid Storm Definition

Rare, life-threatening, sudden exacerbation of hyperthyroidism symptoms; medical emergency requiring immediate treatment

Thyroid Storm Clinical Presentation

Fever, tachycardia, systolic hypertension, N/V/D, agitation, tremors, confusion; can progress to seizures, delirium, coma

Thyroid Storm Treatment

High-dose propylthiouracil (PTU) or methimazole to block new thyroid hormone synthesis; usually resolves in 1-3 days; supportive care critical

Methimazole (Tapazole) Mechanism

Inhibits manufacture of NEW thyroid hormones; does NOT affect existing hormones already circulating or stored in thyroid gland

Methimazole Side Effects

Skin rash, headache, nausea/vomiting, paresthesias

Hypothyroidism vs Hyperthyroidism Metabolic Rate

Hypothyroidism: DECREASED metabolism (slow); Hyperthyroidism: INCREASED metabolism (fast, hypermetabolic)

Hypothyroidism vs Hyperthyroidism Temperature

Hypothyroidism: COLD intolerance (always cold); Hyperthyroidism: HEAT intolerance (always hot)

Hypothyroidism vs Hyperthyroidism Weight

Hypothyroidism: weight GAIN (slow metabolism); Hyperthyroidism: weight LOSS (fast metabolism burns calories)

Hypothyroidism vs Hyperthyroidism Cardiac

Hypothyroidism: BRADYCARDIA (slow heart); Hyperthyroidism: TACHYCARDIA, palpitations, dysrhythmias (fast heart)

Hypothyroidism vs Hyperthyroidism GI

Hypothyroidism: CONSTIPATION (slow bowels); Hyperthyroidism: DIARRHEA (fast bowels)

Hypothyroidism vs Hyperthyroidism Mood

Hypothyroidism: lethargy, fatigue, forgetfulness, depression; Hyperthyroidism: irritability, agitation, anxiety, nervousness

Addison vs Cushing Appearance

Addison: hyperpigmentation, thin, weight loss; Cushing: moon face, buffalo hump, central obesity, purple striae

Addison vs Cushing Blood Pressure

Addison: HYPOTENSION (volume depletion); Cushing: HYPERTENSION (fluid retention)

Addison vs Cushing Sodium

Addison: HYPOnatremia (losing sodium); Cushing: HYPERnatremia (retaining sodium)

Addison vs Cushing Potassium

Addison: HYPERkalemia (retaining potassium); Cushing: HYPOkalemia (losing potassium)

Addison vs Cushing Glucose

Addison: HYPOglycemia (no cortisol for gluconeogenesis); Cushing: HYPERglycemia (excess cortisol raises glucose)

Goiter

Thyroid gland enlargement; can occur in BOTH hypothyroidism (compensatory enlargement from TSH stimulation) and hyperthyroidism (overstimulation)