| TYPE | DEFINITION | CAUSES |
| Functional | Protein <2 g/24 hrNot associated with renal disease | Fever, exercise, congestive heart failureOrthostatic (postural): occurs with standing and is absent in the recumbent state. Urine protein is absent in the first morning void. No progression to renal disease. |
| Overflow | Protein loss is variableLMW proteinuriaAmount filtered > tubular reabsorption | Multiple myeloma with BJ proteinuriaHemoglobinuria: e.g., intravascular hemolysis (e.g., paroxysmal nocturnal hemoglobinuria)Myoglobinuria: crush injuries, McArdle glycogenosis (deficient muscle phosphorylase). Increase in serum creatinine kinase. |
| Glomerular | Nephritic syndrome: protein >150 mg/24 hr but <3.5 g/24 hrNephrotic syndrome: protein >3.5 g/24 hr | Damage of GBM: nonselective proteinuria with loss of albumin and globulins. Example: poststreptococcal glomerulonephritisLoss of negative charge on GBM: selective proteinuria with loss of albumin and not globulins. Example: minimal change disease (lipoid nephrosis) |
| Tubular | Protein <2 g/24 hrDefect in proximal tubule reabsorption of LMW proteins (e.g., aminacids at normal filtered loads) | Heavy metal poisoning: e.g., lead and mercury poisoning Fanconi syndrome: inability treabsorb glucose, aminacids, uric acid, phosphate, and bicarbonateHartnup disease: defect in reabsorption of neutral aminacids (e.g., tryptophan) in the GI tract and kidneys |
