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Creatinine (blood)

Category Biochemistry
Test background

Electrolytes are usually measured as part of a renal profile, which measures sodium, potassium, creatinine and urea. Creatinine is almost completely filtered by the kidneys and increasing serum concentrations correspond with a worsening of the glomerular filtration rate as a function of encroaching kidney failure.

Clinical Indications

Suspected renal failure (acute/chronic)
Monitoring of patients receiving intravenous fluids
Monitoring of established chronic kidney disease

Reference range

Reference ranges are from CALIPER studies for paediatrics and supplier’s information for adults

Sample & container required SST (gold top)
Sample volume 0.5 mL
Turnaround time 1 day
Notes

1. Please be aware that there are reports of falsely raised creatinine levels in some patients with marked hyperproteinaemia due to IgM or IgG, especially those with Waldenstrom’s macroglobulinaemia. If your patient’s creatinine concentrations suggest possible interference, please contact the Duty Biochemist on 020 331 30348 or [email protected].

2. N-acetyl-L-cysteine and Alpha-methyldopa at therapeutic concentrations may cause falsely low results. We will add a comment to all detectable paracetamol results to remind users that when NAC treatment is stopped and creatinine values are no longer affected, a false positive AKI flag may be generated and to interpret with caution.

3. Enzymatic creatinine in use since 28th November 2024. Due to the method change, we are not currently accredited for this test. An application for assessment will be submitted.