Table 1.
Investigation of acute renal failure
| Test | Comment |
|---|---|
|
Urinalysis |
|
| Dipstick for blood, protein, or both |
Suggests a renal inflammatory process |
| Microscopy for cells, casts, crystals |
Red cell casts diagnostic in glomerulonephritis |
|
Biochemistry |
|
| Serial urea, creatinine, electrolytes |
Important metabolic consequences of ARF include hyperkalaemia, metabolic acidosis, hypocalcaemia, hyperphosphataemia |
| Blood gas analysis, serum bicarbonate | |
| Creatine kinase, myoglobinuria |
Markedly elevated creatine kinase and myoglobinuria suggests rhabdomyolysis |
| C reactive protein |
Non-specific marker of infection or inflammation |
| Serum immunoglobulins, serum protein electrophoresis, Bence Jones proteinuria |
Immune paresis, monoclonal band on serum protein electrophoresis, and Bence Jones proteinuria suggest myeloma |
|
Haematology |
|
| Full blood count, blood film |
Eosinophilia may be present in acute interstitial nephritis, cholesterol embolisation, or vasculitis |
| Thrombocytopenia and red cell fragments suggest thrombotic microangiopathy | |
| Coagulation studies |
Disseminated intravascular coagulation associated with sepsis |
|
Immunology |
|
| Antinuclear antibody (ANA) |
ANA positive in SLE and other autoimmune disorders; anti-dsDNA antibodies more specific for SLE |
| Anti-double stranded (ds) DNA antibodies | |
| Antineutrophil cytoplasmic antibody (ANCA) |
Associated with systemic vasculitis; c-ANCA and anti-PR3 antibodies associated with Wegener's granulomatosis; p-ANCA and anti-MPO antibodies present in microscopic polyangiitis |
| Antiproteinase 3 (PR3) antibodies | |
| Antimyeloperoxidase (MPO) antibodies | |
| Complement concentrations |
Low in SLE, acute postinfectious glomerulonephritis, cryoglobulinaemia |
| Antiglomerular basement membrane antibodies |
Present in Goodpasture's disease |
| Antistreptolysin O and anti-DNAse B titres |
High after streptococcal infection |
|
Virology |
|
| Hepatitis B and C; HIV |
Important implications for infection control within dialysis area |
|
Radiology |
|
| Renal ultrasonography | Renal size, symmetry, evidence of obstruction |
ARF=acute renal failure; SLE=systemic lupus erythematosus.