In adults with CKD, what is the biological and analytical variability in eGFR testing and what factors (including fasting) affect it?

Ref ID: 4124
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Ford L, Berg J. Delay in separating blood samples affects creatinine measurement using the Roche kinetic Jaffe method. 2008.Case series

3

1 centre, UK
N volunteers = 10

N outpatients = 113
Inclusion criteria: volunteers and outpatients

Exclusion criteria: not stated

Population baseline characteristics: Volunteers (N=10) age 27–55 years; 90% Caucasian, 10% Asian, 50% male

Outpatients (N=113): age 18–88 years, 52% Caucasian, 39% Asian, 8% Afro-Caribbean, 44% male
Effect of delay in centrifugation of blood samples on creatinine concentration determined by Kinetic Jaffe reaction (Roche kit).

N=10 volunteers
N=113 outpatients

Procedure:
  1. Un-separated Blood experiment: 10 volunteers each provided 7 blood samples (clotted). Samples were kept at RT exposed to light until centrifugation at 0.5 h, 4 h, 8 h, 16 h, 24 h, 36, and 48 h-post collection. All samples were assayed for creatinine with the kinetic Jaffe Roche method standardised against IDMS.
  2. Separated Serum experiment: 10 outpatients each provided a blood sample that was allowed to clot and then centrifuged after 0.5h. The separated (centrifuged) serum was then left at RT exposed to light and aliquots were taken for analysis (kinetic Jaffe, Roche) at 0.5, 4, 8, 16, 24, 36, and 48 h.
  3. 24-h Delay Study: Clotted blood samples were collected in duplicate from N=113 outpatients. The first sample was centrifuged at 0.5h, while the second clotted sample was left un-separated for 24-h at RT, then centrifuged and analysed by kinetic Jaffe (Roche).
  4. Creatinine Enzymatic methods: 10 duplicate samples from the 24-h study with the largest difference between creatinine concentration for samples separated after 0.5 h and a delay of 24-h were analysed with an enzymatic creatinine assay (VITROS 5)
Timely centrifugation of blood samples on creatinine concentration

N=10 volunteers
N=113 outpatients
Not applicableChange in creatinine concentration with delay in centrifugation of blood sample

Change in GFR with delay in centrifugation of blood sample
Not stated
Effect size
Baseline = 0.5 h delay in centrifugation of clotted blood.

Effect of delayed centrifugation of blood samples on creatinine concentration (determined by kinetic Jaffe, Roche):
Delayed centrifugation of clotted blood samples (N=10 volunteers) resulted in a significant increase in creatinine concentration after 16 h (p<0.001). By 48-h, creatinine concentrations had increased above the baseline (centrifugation after 0.5h) by mean 29% (range 21–63%). Mean CV for the seven measures for each volunteer was 11.3% (range 8.1–16.2%)

There was NS change in creatinine concentrations in centrifuged (separated) serum samples left at RT for 0.5, 4, 8, 16, 24, 36, and 48 h. Mean CV for each sample was 4.87% (range 2.38–7.81%)

From the 24-h delay experiment (N=113 outpatients), creatinine concentration significantly increased from baseline (mean 85 micromol/l) to 24-h delay (mean 95 micromol/l, 11% increase, p<0.0004 ) in centrifugation of blood samples. Similar results were seen for males, females, and different ethnicities.

Effect of delayed centrifugation of blood samples on the eGFR (MDRD)
With a 16 h delay in centrifugation, 4/7 volunteers with baseline Stage 1 CKD had changed to Stage 2. By 36 h delay in centrifugation, 7/7 volunteers had changed from Stage 1 to Stage 2 CKD. Three volunteers with baseline Stage 2 CKD did not fall to Stage 3 regardless of length of delay in centrifugation.

From the 24-h delay experiment (N=113 outpatients), eGFR significantly decreased from baseline (mean eGFR 85 ml/min/1.73m2) to 24-h delay (mean eGFR 75 ml/min/1.73m2, 13% decrease, p<0.0001 ) in centrifugation of blood samples. Similar results were seen for males, females, and different ethnicities.

From the 24-h delay experiment (N=113 outpatients), the CKD staging of 32% of the participants changed after a 24-h delay in centrifugation of blood samples. 26% went from Stage 1 CKD to Stage 2 and 6% went from Stage 2 to Stage 3 CKD.

Effect of delayed centrifugation of blood samples on creatinine concentration (determined by Enzymatic method, VITROS):
In contrast to the kinetic Jaffe method (N=10 outpatient samples; mean 29.4% increase in creatinine concentration after 24-h delay in centrifugation, range 19.7 – 86.6%), there was little change in creatinine concentration using the enzymatic method (mean decrease 2.7%, range −13.8 to +8.6%)
Ref ID: 3967
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Fraser CG, Williams P. Short-term biological variation of plasma analytes in renal disease. Clin Chem. 1983; 29(3):508–510. Ref ID: 3967Case series

3
N = 9 patients with CKD (3 mild, 3 moderate, 3 severe CKD)

1 centre, Australia
Inclusion criteria: sequentially recruited adults with CKD

Exclusion criteria : none stated

Population baseline characteristics: Not stated
Biological variability of serum creatinine in adults with CKD N=9

Procedure: Blood samples were collected at 0, 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, 16, 24, 36, and 48 h after administration of 150 mg oral dose or ranitidine.
Samples were promptly centrifuged, aliquoted into 3 separate aliquots and frozen in liquid nitrogen. Serum creatinine concentration determined in an Astra discrete analyser in a single day (calibrated twice). The first aliquot of all samples from a single subject were placed in random order and analysed in a single batch containing quality-control materials (Wellcomtrol Unassayed and Monitrol II.X Control). The Astra was recalibrated and the second aliquot of all samples from a single subject was analysed the same way.
n/aNot applicableBiological variation in serum creatinine measurementsNot stated
Effect size
The CV for serum creatinine for all nine subjects with CKD on all occasions was 61.9% (mean 190.4 micromol/l; SD 117.8 micromol/l).
Biological Variation in serum creatinine concentration
The average analytical variation was 0.1% of the total variance.
The average intra-individual biological variation of creatinine measurements was 1.1% of the total variance.
The average inter-individual variation for serum creatinine was 98.8% of the total variance.
Ref ID: 3971
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Holzel WG. Intra-individual variation of some analytes in serum of patients with chronic renal failure. Clin Chem. 1987; 33(5):670–673. Ref ID: 3971Case series

3
N = 24 healthy volunteers

N=17 patients with CKD

1 centre, Germany
Inclusion criteria: sequentially recruited healthy adults or adults with CKD.

Exclusion criteria : none stated

Population baseline characteristics:
Healthy adults: Age range 20–50 years, mean age 33.5 years (female) and 41.8 years (male), CKD group: 65% glomerulonephritis, 29% chronic pyelonephritis, 6% gouty CKD; serum creatinine range: 255–1125 micromol/l.
Biological variability of serum creatinine in adults with CKD
N=17

Procedure: Blood samples were taken from healthy subjects once a week for 8 weeks. Blood was taken from CKD patients 8 times during 3 weeks and at 4, 8, and 12 weeks after the first collection. Blood samples were drawn after an o/n fast from resting subjects, and samples were centrifuged within 1 hour, and the serum was aliquoted and frozen.
Serum creatinine concentration determined with Jaffe method on a continuous flow analyzer.
Samples were analysed in duplicate within a single run, in random order. Every tenth sample was a control sample. Analyses of blood samples for people with CKD were restricted to blood samples taken within first 3 weeks as CKD process was stable at that time.
Biological variability of serum creatinine in healthy adults
N=24
Not applicableBiological variation in creatinine measurementsNot stated
Effect size
Within-run analytical coefficient of variation for creatinine was 3.3% (in a concentration range of 40–110 micromol/l).
Biological Variation in creatinine concentration
The intra-individual biological variation of creatinine measurements was significantly higher in people with CKD (N=17, CV=5.3%) than in healthy subjects (N=24, CV=2.7%, p<0.01). The ratios of CV for CKD to healthy patients was 1.93 (p<0.01).
Ref ID: 3970
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Holzel WG. Intra-individual variation of some analytes in serum of patients with insulin-dependent diabetes mellitus. Clin Chem. 1987; 33(1):57–61. Ref ID: 3970Case series

3
N = 24 healthy volunteers

N=27 patients with insulin-dependent diabetes

1 centre, Germany
Inclusion criteria: sequentially recruited healthy adults or adults with insulin-dependent diabetes

Exclusion criteria : none stated

Population baseline characteristics: Healthy adults: Age range 20–50 years, mean age 33.5 years (female) and 41.8 years (male), IDDM group: Age range 18–52 years, mean age 31.8 years (females) and 38.7 years (males)
Biological variability of serum creatinine in adults with IDDM
N=27

Procedure: Blood samples were taken from subjects once a week for 8 weeks after an o/n fast from resting subjects, and samples were centrifuged within 1 hour, and the serum was aliquoted and frozen in liquid nitrogen. Serum creatinine concentration determined with Jaffe method on a continuous flow analyzer. Samples were analysed in duplicate within a single run, in random order. Every tenth sample was a control sample.
Biological variability of serum creatinine in healthy adults
N=24
Not applicableBiological variation in creatinine measurementsNot stated
Effect size
Within-run analytical coefficient of variation for creatinine was 3.3% (in a concentration range of 40–110 micromol/l).
Biological Variation in creatinine concentration
The intra-individual biological variation of creatinine measurements was significantly higher in women with insulin-dependent diabetes (N=11, CV=6.53%) than in healthy women (N=14, CV=2.81%, p<0.01). The ratios of CV for IDDM to healthy women was 2.32 (p<0.01).
The intra-individual biological variation of creatinine measurements was significantly higher in men with insulin-dependent diabetes (N=16, CV=5.88%) than in healthy men (N=10, CV=2.64%, p<0.01). The ratios of CV for IDDM to healthy men was 2.23 (p<0.01).
Ref ID: 697
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Jacobsen FK, Christensen CK, Mogensen CE et al. Postprandial serum creatinine increase in normal subjects after eating cooked meat. Proceedings of the European Dialysis & Transplant Association. 1979; 16:506–12, 1979.:506–512. Ref ID: 697Case series

3
N = 6

1 centre in Denmark
Inclusion criteria: sequentially recruited healthy medical students.

Exclusion criteria : not stated

Population baseline characteristics: Not stated
Experiment 1: Meat meal N=6

Experiment 2: Raw beef meal

N=6

Procedure: Experiment 1: After o/n fasting, participants were given a light, non-meat containing breakfast. Participants had a meat-containing lunch containing 500 g goulash (250–300 g beef) and 5 hours later a non-meat supper. Blood samples were taken before and after breakfast, before lunch, and then every hour after lunch until 10 pm. Several days later Experiment 1 was repeated and all 6 participants were given a non-meat lunch.

Experiment 2: Participants were given one of the following meals: 300g raw beef, 300g friend beef, 300g boiled beef ingested with the cooking water, 500g goulash (250–300g beef), 500g stew (250–300g pork). Blood samples were taken before ingestion of the meal and 3 hours after the meal.

Serum creatinine concentration determined by Jaffe reaction on an autoanalyser. 39 samples also assayed for creatinine concentration with ion exchange method (“true creatinine”).
Experiment 1: Non-meat meal N = 6

Experiment 2: Cooked Beef meals

N=6
Not applicableChange in creatinine concentrationNot stated
Effect size
Change in creatinine concentration (kinetic Jaffe method)
Experiment 1: Following a cooked meat goulash lunch (N=6), the mean serum creatinine concentration significantly increased from baseline (86 micromol/L, preprandial) to 175 micromol/L, 3 hours postprandially, p< 0.001). By contrast, following a non-meat lunch, a small increase in serum creatinine was observed 1 hour postprandially, but the serum creatinine concentration was relatively unchanged throughout the time course.

A high correlation between serum creatinine determined by autoanalyser and by ion exchange was observed (N=39 samples).

Experiment 2:
Ingestion of a raw beef meal did NS affect serum creatinine levels.
By contrast ingestion of any type of cooked beef meal (fried, boiled, goulash beef, or stew pork) resulted in a significant increase in serum creatinine. For example, ingestion of fried beef resulted in an increase from baseline serum creatinine 84 micromol/L to 110 micromol/L 3 hours postprandially (p<0.01). Ingestion of boiled beef + cooking water resulted in a significant elevation in serum creatinine from 87 micromol/L to 163 micromol/L postprandially (p<0.001).

Note: Authors suggest serum creatinine measured after fasting or to instruct patient to avoid meat meals prior to creatinine measurements.
Ref ID: 3920
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Mayersohn M, Conrad KA, Achari R. The influence of a cooked meat meal on creatinine plasma concentration and creatinine clearance. British Journal of Clinical Pharmacology. 1983; 15(2):227–230. Ref ID: 3920Case series

3
N = 6

1 centre, USA
Inclusion criteria: sequentially recruited healthy male adults.

Exclusion criteria : not stated

Population baseline characteristics: Age range 26–38 years, mean age 31, mean weight 73 kg, weight range 65–82 kg
Meat breakfast N=6
Procedure: Day 1: All participants were given a light, non-meat containing breakfast: 3 participants had a breakfast containing high amounts of non-meat protein (62g) and 3 subjects had a breakfast of low non-meat protein (11.5g). Subjects had non-meat protein lunch and dinner. Day 2: Each subject ate a breakfast containing 225g of boiled beef. Lunch and dinner the same as Day 1. Fluids were ad libitum. On days 1 and 2, blood samples were taken before and at several time intervals after breakfast. Serum creatinine concentration determined by HPLC (daily calibration curves determined). Creatinine clearance determined from timed urine collections.
Non-meat breakfast N = 6Not applicableChange in creatinine concentrationNot stated
Effect size
Change in creatinine concentration (HPLC method)
Following a cooked meat breakfast (N=6), the mean serum creatinine concentration significantly increased from baseline (52% increase, range 36–65%). By contrast, following either a high or low non-meat protein breakfast (control), serum creatinine remained stable (%coefficient of variation: 2.2 to 4.3%).

CrCl did NS change in response to a cooked meat breakfast.

Note: Authors suggest serum creatinine measured after fasting or to instruct patient to avoid meat meals prior to creatinine measurements.
Ref ID: 3965
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Pasternack A, Kuhlback B. Diurnal variations of serum and urine creatine and creatinine. Scand J Clin Lab Invest. 1971; 27(1):1–7. Ref ID: 3965Case series

3
N healthy volunteers = 9

N paralysed volunteers = 4

1 centre in Finland
Inclusion criteria: sequentially recruited healthy volunteers or paralysed (for greater than 3 years, breathing with respirators and severe muscular atrophy)

Exclusion criteria : not stated

Population baseline characteristics: Age range 22–45 years
non-fasting over 24 hours

N=9

Procedure: Participants fasted for 10 hours prior to the first blood sample taken. Blood samples and urine collections were taken at 7:00, 13:00, 19:00, and at 7:00 the following morning. Meals (cooked meat, potatos, vegetables, bread) were eaten at 11:00 and 16:00, water and other beverages freely taken throughout. Normal activity was allowed from 8:00 to 22:00. In the control experiment, the same participants (excluding paralysed subjects) fasted for 34 hours and blood and urine samples taken as before. During this time, normal activity and water intake was allowed. Serum creatinine concentration determined using picrate method and Lloyd’s reagent (103% recovery). Duplicate creatinine determinations differed by 1.12%.
Fasting over 34 hours

N = 9
Not applicableChange in creatinine concentrationNot stated
Effect size
Change in creatinine concentration
In non-fasting healthy subjects (N=9) or in paralysed subjects (N=4), the creatinine concentration increased significantly during the day, peaking at 19:00 (p<0.001). The creatinine concentration then decreased after 19:00 to 7:00 the next morning.

In fasting subjects (N=9), there was a small but significant decrease in creatinine concentration between 7:00 and 13:00 (p<0.02) and there was no increase in serum creatinine during the rest of the time course. Fasting abolished the diurnal variation in creatinine concentration.
Ref ID: 423
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Pinto JR, Bending JJ, Dodds RA et al. Effect of low protein diet on the renal response to meat ingestion in diabetic nephropathy. European Journal of Clinical Investigation. 1991; 21(2):175–183. Ref ID: 423Case series

3
N = 10

1 centre, Guy’s Hospital, London, UK
Inclusion criteria: proteinuric (protein excretion > 0.5g/24-h persistent for at elast 1 year) insulin-dependent diabetic adults with diabetic retinopathy. None were taking ACE inhibitors. 7 were taking antihypertensive drugs

Exclusion criteria : cardiac failure, clinical/biochemical sign of non-diabetic nephropathy

Population baseline characteristics: Age range 26–38 years, mean age 31, mean weight 73 kg, weight range 65–82 kg

Meat meal on low protein diet

N=10

Procedure: Participants were randomly allocated to a 3-week period on a normal protein diet or a low protein diet (isocaloric with normal protein diet and containing 0.5g/kg body weight per day of protein; half from animal and half from vegetable sources) . At the end of 3 weeks, all patients returned to normal protein diets for 1 week and then switched over to the alternative protein diet for another 3 weeks. Diet assessment from a detailed dietary history and 3-day weighted food record. At the end of each diet period, patients’ GFR measured by inulin clearance before and after a protein meal, consisting of 80g animal protein provided as lean cooked beef. Serum creatinine measurements made at baseline, at the end of each diet period, and before and after a meat meal given at the end of each diet period. Serum creatinine determined on multichannel autoanalyser.
Meat meal on normal protein diet

N = 10
Not applicableChange in serum creatinine concentrationNot stated
Effect size
Protein intake was 45% lower on low protein diet compared with the normal protein diet (p<0.001).

Change in creatinine concentration
Following a cooked meat meal (N=10), the mean serum creatinine concentration significantly increased from baseline (167 micromol/L) to 180 micromol/L in 2 hours (p<0.001) in people on a normal protein diet.

Following a cooked meat meal (N=10), the mean serum creatinine concentration significantly increased from baseline (152 micromol/L) to 161 micromol/L in 2 hours (p<0.02) in people on a low protein diet.
Ref ID: 3921
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Preiss DJ, Godber IM, Lamb EJ et al. The influence of a cooked-meat meal on estimated glomerular filtration rate. Ann Clin Biochem. 2007; 44(Pt 1):35–42. Ref ID: 3921Case series

3
Total N = 32

No. ITT

1 centre in UK
Inclusion criteria: sequentially recruited Caucasian volunteers (healthy and outpatients) age > 18 years.

Exclusion criteria : vegetarianism, any reason for not eating a meat diet, renal dialysis, renal transplantation receipients,

Population baseline characteristics: Age range 18–86 years, median age 54.5, 47% male

Meat meal

N=32

Procedure: A preprandial blood sample was taken 4 hours after a light, non-cooked meat containing breakfast. Participants had either a meat-containing meal (normal helping)or a vegetarian meal. Blood samples were taken after ( 1–2 hours postprandially and 3–4 hours postprandially). 3 determinations of creatinine concentration by kinetic Jaffe (Beckman Coulter LX20) , ID-MS chromatograghy , and enzymatic method (Roche Integra Analyser). eGFR determined from kinetic Jaffe creatinine concentration with IDMS version of MDRD equation. Serum cystatin C concentration was also determined (nephelometric immunoassay).
Vegetarian meal N = 23Not applicableChange in eGFR

Change in creatinine concentration

Change in cystatin C concentration
Not required
Effect size
Change in creatinine concentration (kinetic Jaffe method)
Following a cooked meat lunch (N=32), the median serum creatinine concentration significantly increased from baseline (preprandial) by 20.5 micromol/L 1–2 hours postprandially (p< 0.0001) and by 18.5 micromol/L 3–4 hours postprandially (p<0.0001). Similar results were seen when serum creatinine was measured by ID-MS, and enzymatic methods.

Maximal postprandial serum creatinine concentrations were reached by 18 people at the 1–2 h time and by 12 people at the 3–4 hour time.

By contrast, following a vegetarian lunch (N=23), there was a NS change in median serum creatinine concentration from baseline (preprandial) to 1–2 hours postprandially or 3–4 hours post prandially. Similar results were seen when serum creatinine was measured enzymatically.

Change in eGFR (determined from kinetic Jaffe serum creatinine concentration and MDRD equation)
Following a cooked meat lunch (N=32), the median eGFR significantly decreased from baseline (preprandial) by 24.5 ml/min/1.73 m2 1–2 hours postprandially (p< 0.0001) and by 20 ml/min/1.73 m2 3–4 hours postprandially (p<0.0001).

By contrast, following a vegetarian lunch (N=23), there was a small but significant increase in eGFR from baseline (preprandial) to 1–2 hours postprandially (1.0 ml/min/1.73 m2 , p=0.009) or 3–4 hours postprandially (3.5 ml/min/1.73 m2 , p=0.006).

Following a meat meal, 11 people changed from a pre-prandial eGFR > 59 ml/min/1.73 m2 to a post prandial eGFR of < 60 ml/min/1.73 m2. Effectively, erroneously placing them in Stage 3 CKD.
Change in cystatin C concentration
Following a cooked meat lunch (N=32), there was NS change in median serum cystatin C before and after a meat lunch..
Following a vegetarian lunch (N=23), there was NS change in median serum cystatin C concentration from baseline (preprandial) to 3–4 hours post prandially.

Note: did not sample past 4 hours, no quantification of the amount of meat eaten (although a “normal” portion size), did not evaluate all the dietary constituents of the meals. Authors suggest eGFR measured after fasting or to instruct patient to avoid meat meals prior to eGFR measure.
Ref ID: 3976
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Rapoport A, Husdan H. Endogenous creatinine clearance and serum creatinine in the clinical assessment of kidney function. Can Med Assoc J. 1968; 99(9):149–156. Ref ID: 3976Case series

3
N patients admitted for investigation of kidney disease, hypertension or kidney stones = 89

1 centre in Canada
Inclusion criteria: patients admitted for investigation of kidney disease, hypertension or kidney stones

Exclusion criteria :heart failure, hyperglycemia, glycosuria, ketonuria

Population baseline characteristics: 55% male, Age range 14–58 years
Creatinine concentration following fasting in the morning N=72

Procedure: Blood specimens were drawn in the morning after an o/n fast and again at 4 pm. Participants ate their normal meals and pursued normal hospital activities, while avoiding strenuous exercise. Serum creatinine concentration determined using the Jaffe method.
Creatinine concentration following usual meals in the late afternoon N = 72Not applicableChange in creatinine concentrationOntario heart foundation, Toronto Western Hospital Medical Research Fund
Effect size
Change in creatinine concentration
In patients with inulin clearance ≥ 90 ml/min (N=38), the serum creatinine concentration was significantly greater in the afternoon than in the morning (after an o/n fast) (mean difference 0.087 mg/100ml, p<0.001). Similarly, patients with baseline serum creatinine concentration ≤ 1.4 mg/100ml (N=49) had a significantly greater serum creatinine concentration in the afternoon than in the morning (mean difference 0.092 mg/100ml, p<0.001).

By contrast, there was NS difference in serum creatinine concentration between morning and afternoon in patients with inulin clearance < 90 ml/min (N=34, mean difference 0.035 mg/100ml). Similarly, there was NS difference in serum creatinine concentration between morning and afternoon in patients with baseline serum creatinine concentration > 1.4 mg/100ml (N=23, mean difference 0.000 mg/100ml).
Ref ID: 3922
ReferenceStudy type
Evidence level
Number of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Shepherd J, Warner M, Kilpatrick E. Stabilty of creatinine with delayed separation of whole blood and implications for eGFR. Ann Clin Biochem. 2007; 44:1–4. Ref ID: 3922N healthy volunteers = 5

N patients = 24

1 centre in UK
Inclusion criteria: sequentially recruited non-fasting volunteers (healthy and outpatients) age 27–64 years.

Exclusion criteria : not stated

Population baseline characteristics: Not stated
Effect of delay in centrifugation of blood samples on creatinine concentration determined by Kinetic Jaffe reaction.

N=5
N=24

Procedure: Each subject provided six blood samples. Samples were kept at RT until centrifugation at 15 min, 4 h, 8 h, 14 h, 24 h, and 31 h-post collection. All samples were assayed for creatinine with 3 different kinetic Jaffe methods: Beckman DXC 800, Bayer Advia, Roche Modular P-800. The samples were also assayed for creatinine with 2 enzymatic assays: Roche-Modular P-800 enzymatic assay and Vitros 5.1 enzymatic assay. The between batch CV for each method was < 2% at a level of 100 micromol/L. 24 patients provided two blood samples each. One sample of each pair was promptly centrifuged and assayed for creatinine (within 1 hour of receipt) by the kinetic Jaffe (DXC 800 autoanalyser). The other sample was left at RT and centrifuged up to 28 h later. eGFR was determined on each sample.
Effect of delay in centrifugation of blood samples on creatinine concentration determined by enzymatic methods

N=5
N=24
Not applicableChange in eGFR with delay in centrifugation of blood sample

Change in creatinine concentration with delay in centrifugation of blood sample
Not stated
Effect size
Effect of delayed centrifugation of blood samples on creatinine concentration:
Using 3 different kinetic Jaffe methods (Beckman, Bayer Advia, Roche), the creatinine concentration remained stable in blood (N=5 healthy volunteers, 30 samples total) up to 14 hours before centrifugation. A 24-h delay in centrifugation resulted in significant increases in creatinine concentration (mean difference Beckman DXC + 19.7 micromol/l ; Roche + 10.2 micromol/l ; Bayer Advia + 6.2 micromol/l, p<0.025).

Analysis of 24 pairs of blood samples taken from 24 patients showed NS difference in creatinine concentration before 10 h delay in centrifugation (p=0.46). Significant increases in creatinine concentration were seen after 10–24 h delay in centrifugation (P<0.001) (Beckman kinetic Jaffe method).

By contrast, the creatinine concentration remained stable, regardless of the delay in centrifugation, when assayed with enzymatic methods (N=5 healthy volunteers, 30 samples total; Roche, Vitros enzymatic methods).

Effect of delayed centrifugation of blood samples on the eGFR (determined from kinetic Jaffe Beckman DXC 800)
In 21 patients where the delay in centrifugation exceeded 10 h, the eGFR significantly decreased (p<0.001). This resulted in a change in CKD classification in 4 of these cases.

Note: authors recommend centrifugation of blood samples within 10 hours of receipt. Enzymatic methods show less variation, indicating that the instability of creatinine observed with the Jaffe method is not due to creatinine itself but to some other interfering factor (non-creatinine chromogen??)

From: Evidence Tables

Cover of Chronic Kidney Disease
Chronic Kidney Disease: National Clinical Guideline for Early Identification and Management in Adults in Primary and Secondary Care.
NICE Clinical Guidelines, No. 73.
National Collaborating Centre for Chronic Conditions (UK).
Copyright © 2008, Royal College of Physicians of London.

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