Creatinine (serum)

 

Alternative names, keywords

Renal function, eGFR, AKI.

Samples required

● Clotted blood (gold cap, 5 mL tube). Smaller tubes are available for paediatric samples.

For eGFR, best taken more than 12h after eating meat (NICE clinical guidelines CG73 Chronic kidney disease).

Samples received more than 8 hours after venepuncture are unsuitable for analysis. 

Test indications

Investigation of renal function. Click for information on eGFR and AKI.

Factors affecting test performance/ results

Haemolysed samples from neonates, infants or adults containing high HbF concentrations are subject to interference.

In very rare cases, gammopathy, in particular type IgM (Waldenström’s macroglobulinemia), may cause unreliable results.

Rifampicin, levodopa and calcium dobesilate (and methyldopa if tested to CSLI recommendations) cause artificially low creatinine results.

Dicynone (Etamsylate) at therapeutic concentrations may lead to falsely low results.

N-ethylglycine at therapeutic concentrations and DL-proline at concentrations ≥ 1 mmol/L (≥ 115 mg/L) give falsely high results.

2-Phenyl-1,3-indandion (Phenindion) at therapeutic concentrations interferes with the assay.

Paracetamol intoxications are frequently treated with N-Acetylcysteine. N-Acetylcysteine at a plasma concentration above 333 mg/L and the paracetamol metabolite N-acetyl-p-benzoquinone imine independently may cause falsely low results.

Venepuncture immediately after or during the administration of metamizole may lead to falsely low results. A significant interference may occur at any plasma metamizole concentration.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Reference range

male: 59 - 104 µmol/L
female: 45 - 84 µmol/L

Neonates (premature) 29 - 87 µmol/L
Neonates (full term) 27 - 77 µmol/L
2 to 12 months 14 - 34 µmol/L
1 to <3 years 15 - 31 µmol/L
3 to <5 years 23 - 37 µmol/L
5 to <7 years 25 - 42 µmol/L
7 to <9 years 30 - 47 µmol/L
9 to <11 years 29 - 56 µmol/L
11 to <13 years 39 - 60 µmol/L
13 to <15 years 40 - 68 µmol/L
15 years and over see adult ranges

Source: Roche Cobas ® Enzymatic Creatinine kit insert 2024-10, V15.0 
 

Turnaround time

Same day (within 1h if urgent)

Enquiries

Biochemistry (Automation)
 

AKI (Acute Kidney Injury)

AKI is detected by any of the following criteria (taken from from NICE Guidance CG169 published August 2013):

  • a rise in serum creatinine of 26 µmol/L or greater within 48h,
  • a 50% or greater rise in serum creatinine known or presumed to have ocurred within the past 7 days,
  • a fall in urine output to less than 0.5 mL/kg/hr for more than 6 hours for adults and more than 8 hours in children or young people,
  • a 25% or greater fall in eGFR in children and young people.*

    * Caution - the equation used to calculate eGFR is not valid for under 18s or in acute renal impairment. Click Click here for information on eGFR

 

Details