SIADH vs. Diabetes Insipidus (DI)

SIADH vs. Diabetes Insipidus (DI)

• SIADH involves excessive water retention due to too much ADH.
• DI involves excessive water elimination due to ADH deficiency.

SIADH (Syndrome of Inappropriate ADH)

• Caused by over-production of ADH by the pituitary gland, head trauma, or cancers.
• Clinical manifestations include thirst, neurological changes (from hyponatremia), weight gain, edema, hypervolemia, and decreased urine output.
• Diagnostic labs show hyponatremia, with sodium levels possibly as low as 110-15 mEq/L, potentially causing neurological damage
• Serum osmolality is decreased (less than 270 mOsm/kg)
• Urine osmolality is increased (high specific gravity).
• Management includes treating the underlying cause, restricting fluids (800-1000mL/day), replacing sodium (NS; 3%NSS), and using diuretics.

DI (Diabetes Insipidus)

• Caused by idiopathic factors or damage to the hypothalamus/pituitary/surgical damage.
• Clinical manifestations include thirst, neurological changes (from hypernatremia), polyuria (8-12 L/day; normal is 1-2 L/day), weight loss, hypotension, and signs of dehydration.
• Diagnostic labs show hypernatremia
• Serum osmolality increased (over 290 mOsm/kg).
• Urine osmolality decreased (low specific gravity).
• Management involves treating hypernatremia, ADH replacement with desmopressin acetate (DDAVP), and addressing the underlying cause.

Hyperthyroidism

• Characterized by excessive levels of thyroid hormones, causing a hypermetabolic state.
• It is less common than hypothyroidism.
• Excess thyroid hormone is secreted from the thyroid gland.
• Causes include Graves' disease, nonmalignant thyroid tumors, thyroid inflammation, and excessive thyroid hormone replacement.
• Diagnosis involves history, physical examination, and serum thyroid hormone levels (↑T4 and T3, ↓ serum TSH).
• Treatment includes methimazole or propylthiouracil (antithyroid drugs), radioactive iodine, and surgery.
• Thyroid crisis (storm) called thyrotoxicosis, is a sudden worsening of hyperthyroidism symptoms, often due to infection or stress.
• Thyroid storm is potentially life-threatening within 48 hours if untreated.
• Symptoms of thyroid storm include hyperthermia, tachycardia (especially atrial tachydysrhythmias), high-output heart failure, agitation/delirium, nausea, and vomiting.
• Thyroid Storm warrants medical emergency treatment with medications to block thyroid hormone synthesis and beta-blockers.

Hypothyroidism

• Characterized by insufficient thyroid hormone production.
• It affects 1 out of 500 Americans.
• It results from the hypothalamus, pituitary, or thyroid dysfunction.
• Risk factors include advancing age and autoimmune thyroiditis (Hashimoto’s)
• Primary hypothyroidism can be caused by iodine deficiency (endemic goiter) worldwide and Autoimmune thyroiditis (Hashimoto disease) most common in the United States
• Diagnostics include history, physical examination, serum thyroid hormone levels (↓ T3/T4 and ↑ TSH).
• Treatment involves synthetic thyroid hormone replacement (levothyroxine), weight management, constipation measures, and avoiding cold temperatures.
• Myxedema coma is a rare, life-threatening advanced hypothyroidism with a mortality rate of 25%.
• Myxedema coma manifestations are marked hypotension, bradycardia, respiratory depression, hypothermia, lethargy, and coma.

Hyperparathyroidism

• Primary hyperparathyroidism involves excess PTH secretion from one or more parathyroid glands.
• Secondary hyperparathyroidism involves elevated PTH secondary to a chronic disease.
• Clinical manifestations include hypercalcemia, hypophosphatemia, and signs/symptoms of hypercalcemia.
• Diagnostics include monitoring calcium and PTH levels.

Hypoparathyroidism

• Results from abnormally low PTH levels
• Typically caused by parathyroid damage during thyroid surgery.
• Clinical manifestations include hypocalcemia and hyperphosphatemia.
• Signs and symptoms of hypocalcemia.
• Diagnostics include monitoring calcium and PTH levels

Cushing's Syndrome

• Characterized by excessive cortisol levels.
• It can be caused by iatrogenic factors (corticosteroid medications) or pituitary/adrenal tumors.
• Clinical manifestations include hypertension, sodium/water retention, weight gain in the trunk/facial/cervical areas ("truncal (central) obesity," "moon face," "buffalo hump").
• Additional clinical manifestations include hypernatremia, hypokalemia, and hyperglycemia (insulin resistance).
• Diagnosis can be difficult, involving history, physical, and cortisol tests (blood, urine, or saliva).
• Treatment depends on the cause and may involve removing tumors, discontinuing medication, and managing blood pressure, potassium, and blood sugar levels.

Addison's Disease

• Characterized by a deficiency of adrenal cortex hormones (glucocorticoids, mineralocorticoids, and androgens).
• Its auto-immune related and is caused by tumors and pituitary dysfunction leading to insufficient ACTH levels.
• Clinical manifestations include hyperkalemia.
• Hyponatremia (salt craving), and hypotension,.
• Hypoglycemia.
• Diagnosis involves history, physical examination, serum hormone levels (cortisol, ACTH, androgens), serum glucose levels, blood chemistry, and adrenal/pituitary CT/biopsy.
• Treatment involves lifetime glucocorticoid and mineralocorticoid replacement therapy and 150 mEq sodium per day.
• Those with Addison's need to wear a medical alert bracelet and carry extra medication.