| Uremia | Kidney failure → urea accumulates in blood | Nausea, vomiting, fatigue, confusion, coma | Urea in blood (not uric acid) |
| Renal Calculi | Supersaturation of calcium oxalate, uric acid, or phosphate in urine → crystal formation | Severe flank pain (renal colic), haematuria (blood in urine), urinary obstruction | Most common = calcium oxalate (~70–80%) |
| Glomerulonephritis | Autoimmune or post-streptococcal inflammation of glomeruli | Haematuria, proteinuria, decreased GFR, hypertension, oliguria, oedema | Nephritic syndrome (haematuria + HTN + oliguria) |
| Nephrotic Syndrome | Glomerular barrier damage → massive protein loss | Massive proteinuria (>3.5 g/day), hypoalbuminaemia, generalised oedema | Oedema from low oncotic pressure (albumin loss) |
| Renal Failure | Progressive loss of kidney function (acute or chronic) | Oliguria (<400 mL/day) or anuria (<100 mL/day), elevated creatinine and urea | GFR drops severely; serum creatinine doubles when GFR halves |
| Diabetes Insipidus | ADH deficiency (central) or renal ADH resistance (nephrogenic) | Polyuria dayupto20L, dilute urine, polydipsia, dehydration | NOT the same as diabetes mellitus (no glucose) |
| Haemodialysis (treatment) | Artificial kidney filtration for renal failure | Blood filtered through semipermeable membrane against dialysing fluid | Dialysing fluid contains normal glucose + amino acids; zero urea |