Application Note — Clinical Connections — Notes | NoteTube

Clinical Scenario 1: Uremia

Kidney failure → urea accumulates in blood → toxicity → nausea, vomiting, fatigue → coma if untreated. Treatment: Haemodialysis (semipermeable membrane filtration) or kidney transplant.

Clinical Scenario 2: Renal Calculi

Supersaturation of Ca2+ oxalate (most common, ~70–80%), uric acid, or phosphate in urine → crystals form → obstruction → severe flank pain (renal colic) + haematuria. Prevention: High fluid intake (dilutes urine), dietary modification (reduce oxalate, animal protein).

Clinical Scenario 3: Glomerulonephritis

Inflammation of glomeruli (autoimmune or post-streptococcal) → filtration barrier damaged → proteinuria + haematuria + decreased GFR + oedema. Oedema mechanism: Protein loss → low plasma albumin → low oncotic pressure → fluid leaks into tissues.

Clinical Scenario 4: Diabetes Insipidus (DI)

ADH deficiency (central DI) or kidney unresponsive to ADH (nephrogenic DI) → collecting duct impermeable to water → up to 20 L/day dilute urine (polyuria) + severe thirst (polydipsia) + dehydration. NOT to be confused with diabetes mellitus (which involves glucose, not water).

Clinical Scenario 5: Hyperaldosteronism (Conn's Syndrome)

Excess aldosterone from adrenal cortex tumor → excessive Na+ retention + K+ loss → hypertension + hypokalaemia + low renin levels.

Clinical Scenario 6: SIADH (Syndrome of Inappropriate ADH)

Excess ADH (from tumors, CNS disease, drugs) → excessive water retention → blood diluted → hyponatraemia (dilutional) → confusion, seizures.

Clinical Scenario 7: Heart Failure and Oedema

Low cardiac output → perceived as low BP → RAAS activated + ADH released → Na+ and water retained → worsens fluid overload → pulmonary and peripheral oedema despite high ANF levels (RAAS overwhelms ANF).

Key Clinical Values

Normal urine output: 1–1.5 L/day (oliguria <400 mL/day; anuria <50 mL/day)
GFR normal: 125 mL/min (60–120 mL/min is broadly normal in adults)
Urine protein (normal): <150 mg/day (nephrotic: >3.5 g/day)
Normal serum creatinine: ~0.7–1.2 mg/dL (doubling indicates ~50% GFR reduction)