Examination
17718
Purpose of test
Creatinine (Creat, eGFR, AKI)
For the assessment of renal function
As creatinine is age and muscle mass dependant it is
recommended that eGFR is used to identify and monitor
patients with chronic kidney disease
Acute Kidney Injury alert models are based primarily on
the change in creatinine
Sample
Blood
Sample Tube/Container
Adult- Yellow top or Green top Lithium Heparin Gel
Paediatric- Green top Lithium Heparin Gel
Sample Volume
4ml (blood)
Minimum (see calculation of minimum volume)
Special Precautions
Please note that, for the purpose of eGFR calculation, the
SHSCT laboratory measures creatinine by an IDMS
traceable enzymatic creatinine method
Request Form:
Clinical Chemistry & Haematology Requests
Laboratory
Biochemistry
Biological reference range
Creatinine
Adults:
Male:
59-104 umol/L
Female: 45-84 umol/L
Paediatrics:
Neonate (premature)
Neonate (Full Term)
2-12mth
1-<3yrs
3-<5yrs
5-<7yrs
7-<9yrs
9-<11yrs
11-<13yrs
13-<15yrs
2 - 87 umol/L
27 - 77 umol/L
14 - 34 umol/L
15 - 31 umol/L
23 - 37 umol/L
25 - 42 umol/L
30 - 47 umol/L
29 - 56 umol/L
39 - 60 umol/L
40 - 68 umol/L
eGFR
60-150 ml/min
The terms stage 1 and stage 2 CKD are only applied when
there is a structural abnormality, as determined by renal
ultrasound, such as polycystic kidney disease or a
functional abnormality such as persistent proteinuria or
microscopic haematuria
If there is no such abnormality, a GFR of >60 i.e. (60–89)
ml/min/1.73 m² is not regarded as abnormal
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Clinical decision values
400 umol/L (100 if <16years)
Factors affecting performance In sample where icterus (bilirubin), haemolysis or lipemia
is indicated by the manufacturer to cause inaccuracy of
>10%, the result will be dashed out or reported with a
disclaimer
Creatinine and eGFR
eGFR has not been validated for use in acute renal failure,
pregnancy, oedematous states, muscle wasting disorders,
amputees and malnourished people
Due to increased variability eGFR >60 are not reported as
per NI recommendations
The MDRD equation should not be used in children
Extremes of muscle mass result in high or low levels
10% of creatinine is derived from dietary sources
Hydration status
Rifampicin, Levodopa and calcium dobesilate (e.g.
Dexium) cause artificially low creatinine results
N-ethylglycine at therapeutic concentrations and DLproline 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
Dicynon (Etamsylate) at therapeutic concentrations may
lead to falsely low results
In very rare cases gammopathy, in particular type IgM
(Waldenström’s macroglobulinemia), may cause unreliable
results
Recovery may be falsely low when a blood sample is
taken while levels of N-Acetylcysteine(NAC), the
paracetamol metabolite N-acetyl-p-benzoquinone imine
(NAPQI), and Metamizole are still present
Venepuncture should be performed prior to the
administration of Metamizole
Venepuncture immediately after or during the
administration of Metamizole may lead to falsely low results
Acetaminophen, Acetylcysteine and Metamizole are
metabolised quickly. Therefore, interference from these
substances is unlikely but cannot be excluded
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Turnaround times:
The Laboratory aims to report 90% of requests within the
stated time from receipt
Urgent - 1 hour
Ward - 4 hours
GP and OPD – 1 working day
Patient preparation
Fasting sample preferred but not essential
Please note the publication by Jacobsen FK, et al
Proc Eur Dial Transplant Assoc. 1979;16:506-12. provides
a guide to the impact of cooked meat on creatinine levels
Instructions for patient
collected sample
Not applicable
Sample transportation
No specific requirements
Special handling needs
No specific requirements
Patient consent required
Implied consent
Specific rejection criteria
Generic rejection applies
Additional information
Stability:
Whole blood – 2 to 3 days at room temperature
Serum/plasma – 7 days at 2-8˚C
Samples are kept in the laboratory for a maximum of 5
days post analysis
Minimum Retest IntervalsStable patent
4 days
Stable patient on IV fluids
24 hours
Symptomatic patient
2-4 hours
(administered hypertonic saline)
AKI- 24 hours
ACE (monitoring)- 1 week after dose change, then annually
Diuretic therapy- before initiation of therapy and after 4
weeks, and then 6 monthly
Digoxin (monitoring)- 8 days after dose change, then
annually
Digoxin and diuretics- regular
Aminosalicylates- in the elderly, every 3 months in first
year, then every 6 months for next 4 years then annually
after that based on personal risk factors
Carbamazepine- 6 months
Anti-psychotics- 12 months
Part of electrolyte profile
In NI we apply the ACB AKI alert algorithm.
http://www.acb.org.uk/whatwesay/acb_newspage/2013/09/
26/e-alerts-for-aki-meeting-report
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http://www.acb.org.uk/docs/appendix-a-algorithm.
The SHSCT reports an eGFR alongside a creatinine
request for all patient >18. The formula used the 4variable (i.e. serum creatinine concentration, age, gender
and ethnic origin) isotope dilution mass spectrometry (IDMS) traceable version of the Modification of Diet in Renal
Disease (MDRD) equation:
GFR (ml/min/1.73 m²) = 175 x [serum creatinine
(umol/L) x 0.011312]-1.154 x [age]-0.203 x [1.212 if
black]x [0.742 if female]
Please note that we assume Caucasian ethnicity. The
eGFR should be multiplied by 1.212 for African-Caribbean
patients
For the calculation of eGFR in children the new IDMS
traceable Schwartz formula should be used.
EGFR = height (cm) X 40/Creatinine (µmol/L)
Schwartz et al J Am Soc Nephrol 20: 629-637, 2009
In relation to drug dosing there is still some controversy
over whether the use of the traditional Cockcroft and Gault
eCrCl formula with IDMS traceable method or the IDMS
traceable MDRD eGFR formula is best.
Http://nkdep.nih.gov/resources/CKD-drug-dosing.shtml
Please note that the use of IDMS traceable creatinine
result generated by the SHSCT laboratory with traditional
Schwartz or Cockcroft and Gault formula may lead to an
overestimation
References
Lab Tests Online
Roche insert 2016-02 v8.0
WHO use of anticoagulants in diagnostic laboratory
investigations
William Marshall. Creatinine ACB 2012
Estimating glomerular filtration rate information for
laboratories NHS 2006
Chronic kidney disease and drug dosing information for
providers NKDEP NIDDK 2010
Junge et al. Determination of reference intervals for serum
creatinine with an enzymatic and modified jaffe method.
Clin chem acta 2004, 344, 137-148.
Tim Lang ACB MRI 2013
Schwartz EGFR formula sourced from email
communication attached to CR1933
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