Diagnostic Use
Plasma creatinine is increased in acute and chronic renal impairment, and any condition which reduces the glomerular filtration rate (e.g. circulatory failure; post-renal obstruction).
Creatinine is formed from creatine in muscle cells, and the plasma creatinine level is dependent on muscle mass. In patients with unusually low or high muscle mass, the plasma creatinine level and the eGFR may give a misleading indication of renal function.
Levels are lower in patients with a reduced muscle mass (e.g. the elderly) and this may conceal impairment of renal function.
Ingestion of meat or fish can raise the plasma creatinine level by up to 25 umol/L for up to 8 hours.
Test Method
Principle: Enzymatic
Reagents: Siemens Atellica CH Enzymatic Creatinine
Analyser: Siemens Atellica Solution (NSH) and Atellica CI (WTH)
Limitations / Interference
Patients with monoclonal gammopathies may produce falsely elevated results.
Venipuncture should occur prior to N-Acetyl Cysteine (NAC) or Metamizole (Sulpyrine) administration due to the potential for falsely depressed results.
Patients on treatment with Calcium dobesilate and N-ethylglycine (a metabolite of lidocaine) may produce falsely elevated results.
Patients on treatment with the following substances may falsely depress results:
- N-Acetyl Cysteine (NAC)
- Metamizole (Sulpyrine)
- N-acetyl-pbenzoquinoneimine (NAPQI)
- Methyl dopa
- Rifampicin
- Dicynone(etamsylate)
- Phenindione
Increased total bilirubin > or = 350 umol/L may falsely decrease creatinine measurement. Creatinine testing should be performed using an alternate enzymatic method.
A high protein meal or taking creatine supplements hours before testing can cause falsely high results.