Abstruse

Background Large claret-based epidemiological studies require uncomplicated, cost-effective sample collection methods. Immediate sample separation or rapid transport of chilled blood samples to a central laboratory may be impractical or prohibitively expensive. To assess the feasibility and reliability of transporting claret samples over several days at ambient temperature (e.thousand. by postal service), we evaluated the stability of diverse plasma analytes in samples stored at room temperature or chilled.

Methods Multiple vacutainers of blood, containing EDTA and aprotinin as preservative, were fatigued from 12 volunteers and stored at 21°C or 4°C. Immediately later on drove and 1, 2, three, four, and vii days later on, vacutainers stored at each temperature were centrifuged, and the plasma was aliquoted and stored at –80°C. Subsequently, all aliquots from each individual were analysed in one analytical run for a range of chemistries.

Results In whole blood stored at room temperature for upwardly to seven days, concentrations of albumin, apolipoproteins A1 and B (apoA1 and apoB), cholesterol, loftier density lipoprotein (HDL), total protein, and triglycerides changed past less than 4%, and low density lipoprotein (LDL) by less than 7%. Whilst alanine transaminase (ALT), creatine kinase (CK), creatinine, and γ-glutamyl transferase (GGT) concentrations changed substantially at room temperature, at that place was less than 4% change during chilled storage upwardly to 7 days. By contrast, aspartate transaminase (AST) concentrations increased markedly under both conditions.

Conclusions A wide range of important analytes, including lipids, change by merely a few per cent in whole claret during storage at room temperature for several days. Mailed transport of whole claret samples may, therefore, be a unproblematic and cost-effective option for large-scale epidemiological studies.

Observational epidemiological studies can often exist profoundly enhanced by the inclusion of biochemical analyses in stored blood samples nerveless from the population being studied. Biochemical analyses can be used to assess risk factor exposure, to control for confounding, or to measure the furnishings of bias. In randomized trials, biochemical analyses tin can be used to monitor the safety and biochemical efficacy of handling. For epidemiological studies to be informative, they oftentimes need to exist large (perhaps involving tens or hundreds of thousands of individuals), which in turn requires methods for claret collection that are practical and cost-effective. Standard guidelines for blood sample handling country that plasma or serum should exist separated from cells every bit soon every bit possible and certainly within2 hours. 1 Whilst this is necessary for particular analytes, it might exist assumed that many blood analytes deteriorate within a matter of hours in unseparated samples kept at ambience temperature. This perceived need for either immediate local separation of blood samples or their rapid chilled transfer toa primal laboratory, which increases complexity and price, tin can forestall claret collection from beingness included in large-scale epidemiological studies.

Particularly when blood samples are being collected in a large number of divide sites within a report, mailing of whole claret samples to a central laboratory for separation may be more convenient and price-constructive than making arrangements for local separation or for courier transport of chilled samples. Saliva samples have been successfully collected by post for measurement of hepatitis B virus seropositivity 2 and the potential advantages of collecting blood samples past mail in epidemiological studies have been noted. 3 There is limited evidence to suggest that some biochemical analytes (such as total cholesterol) may be stable in whole blood for several days at ambient temperature. four– six If confirmed for a wider range of analytes of interest, use of mailed whole blood samples might allow blood drove to exist included in studies where it would not otherwise exist considered feasible. Nosotros have evaluated the utilise of mailed whole blood samples and of chilled samples (compared with immediate plasma separation) by simulating these two collection methods in the laboratory, and assessing their impact on the stability of a range of blood analytes.

Materials and Methods

Subjects and procedures

Twelve 10 ml vacutainers of blood containing 0.12 ml preservative (15% potassium EDTA with aprotinin 0.34 mmol/l [Becton Dickinson UK Limited, Oxford, England]) were fatigued from each of 12 non-fasting volunteers (5 males and 7 females, aged 25–sixty years). Each vacutainer corresponded to a particular storage temperature (room temperature or chilled) and separation time-betoken (immediate or 1, ii, 3, four, or seven days postal service-drove), which were randomly assigned within each volunteer'due south prepare of vacutainers using a random number tabular array.

2 of the 12 vacutainers from each individual were centrifuged immediately after drove (2100 g for 15 minutes at 4°C), and the plasma was aliquoted into 1.eight ml Nunc cryotubes (Nunc A/South, Roskilde, Kingdom of denmark) and stored at –80°C. The remaining 10 vacutainers from each private were covered in aluminium foil to forestall any potential effect from low-cal (since samples would be unlikely to be exposed to light during transportation) and kept at room temperature (defined every bit 21°C) or chilled (four°C). At each subsequent time-betoken, a vacutainer from each temperature for each volunteer was retrieved, centrifuged and the plasma aliquoted and stored at –eighty°C. (An on-going study in our laboratory has plant no change in concentrations of any of the analytes in plasma samples stored at –80°C during up to 5 years.)

Biochemical analyses

Prior to analysis, the frozen samples were left to stand at room temperature to thaw, then inverted several times to mix. The plasma aliquots from all temperature and time-points for each volunteer were analysed together in one batch, to avoid run-torun variability, for the following analytes: alanine transaminase (ALT), albumin (past the bromocresol purple method), apolipoproteins A1 and B (apoA1 and apoB), aspartate transaminase (AST), creatine kinase (CK), creatinine (by the Jaffe rate method), γ-glutamyl transferase (GGT), high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol, total protein (by the charge per unit biuret method), and triglycerides. Measurements were performed on a Synchron LX20 autoanalyser (Beckman Coulter United kingdom Limited, High Wycombe, England), using Beckman Coulter reagents, calibrators, and controls for all assays, except for HDL and LDL which were analysed using North-geneous reagents, calibrators, and controls (Bio-Stat Limited, Stockport, England). These directly methods for quantification of HDL and LDL were fully automated, involving chemical isolation of the lipoprotein and enzymatic measurement of cholesterol. The Synchron LX20 autoanalyser monitors absorbance readings at multiple wavelengths and was programmed to decrease a sample blank absorbance reading from the final reaction absorbance where possible. vii This helps to correct for interference from color in plasma due to haemolysis, which was a pregnant trouble in samples from the after fourth dimension-points. The intra-assay coefficient of variation (CV) for ALT was four% at a quality control level of 24.0 U/l and ane% at a quality control level of 84.3 U/l; for albumin was 1% at 29.3 1000/fifty and 2% at 47.2 thousand/50; for apoA1 was three% both at 83.9 mg/dl and 279.vii mg/dl; for apoB was four% both at 95.7 mg/dl and 200.9 mg/dl; for AST was 3% at 29.eight U/l and 1% at 100.4 U/l; for CK was 3% at 56.nine U/l and 1% at 394.0 U/50; for creatinine was 9% at 73.6 μmol/fifty and iii% at 325.one μmol/l; for GGT was 7% at 20.ane U/l and iii% at 107.4 U/l; for HDL was five% both at 0.7 mmol/l and ii.2 mmol/l; for LDL was 5% both at 2.5 mmol/50 and 5.half-dozen mmol/fifty; for cholesterol was two% both at 4.3 mmol/50 and ix.9 mmol/l; for total protein was 1% both at 45.7 thou/l and 73.7 chiliad/fifty; for triglyceride was 3% both at 2.0 mmol/l and 4.7 mmol/l.

Data assay

For each individual, the hateful analyte concentration from analysis of the two samples that had been separated and frozen immediately was used every bit the baseline 'fresh' value against which analyte concentrations at future fourth dimension-points were compared. The stability of an analyte under each temperature condition was determined past calculating the percent alter in concentration from the hateful fresh value at each time-point for each individual, and so calculating the mean per centum change from fresh (and standard error of the mean) at each time-bespeak from the individual data. Log-linear regression, incorporating a term for individual, was used to determine the percentage change per 24-hour interval for each analyte in samples kept at room temperature and chilled; to test for pregnant differences in analyte concentrations betwixt storage temperatures; and to examination for significant trends over fourth dimension at each temperature. Information analysis was performed using SAS (SAS Establish Inc, Cary, NC, Us).

Results

Table 1 shows the results obtained in samples separated immediately after collection from the volunteers, along with the reference intervals for each analyte. On the whole, the results obtained for each analyte give good coverage of the reference interval, with some results beingness outside of this range.

Tabular array 2 shows the hateful pct change in plasma analyte concentrations at each time-indicate, for samples stored at room temperature (21°C) and chilled (4°C). Figure 1 summarizes the data by showing the mean per centum alter per solar day for each analyte under each temperature condition. At 21°C, the concentrations of albumin, apoA1, apoB, total cholesterol, HDL, total protein, and triglycerides differed by less than four% from the fresh value up to 7 days after blood collection, while the concentration of LDL differed by less than 7%. The mean pct modify per day at room temperature was less than 0.v% for all of those analytes, except for HDL and LDL where information technology was less than 1%. With the exception of total cholesterol, the change over fourth dimension did not differ significantly between samples stored at 21°C or 4°C. For total cholesterol, there was a significant difference (P = 0.0003) betwixt the values in samples kept at the different temperatures, but information technology was small and did not go apparent until 7 days.

Past contrast, concentrations of ALT, CK, creatinine, and GGT changed more markedly at 21°C: for example, creatinine increased past more than than 20% in whole claret after three days. Under chilled weather at 4°C, even so, these analytes were more stable, and changed by less than iv% in whole blood after seven days (P < 0.0001 for 21°C versus 4°C). The hateful per centum change per day for these analytes under chilled weather was less than 0.7%. Although a significant trend (P = 0.0008) towards an increment in CK values was observed over time in samples kept at 4°C, the alter was small. Of the analytes measured, simply AST was found to change substantially nether both temperature conditions. The concentration of AST increased past more than seven% after 3 days at 4°C, and by more than than 15% after just 1 mean solar day at 21°C. The percentage changes in ALT and AST appeared to be somewhat greater in the samples with lower baseline levels compared with higher baseline levels, but more than individuals with a wider range of baseline values would need to exist studied to assess this reliably.

Discussion

The stability of a wide range of plasma analytes in whole blood samples stored for several days is much better than had perhaps been widely believed. The present study demonstrates that albumin, apoA1 and apoB, total cholesterol, HDL, LDL, poly peptide, and triglycerides can be measured reliably in whole blood samples kept at room temperature for at to the lowest degree a week before plasma separation. Alanine transaminase, CK, creatinine, and GGT exhibited greater change at room temperature, hence reliable quantification of these analytes would require whole claret samples to be kept chilled before separation. However, since the mean concentrations of these analytes were institute to change by less than 4% during up to seven days in chilled blood, such samples practice not require rapid transfer to a central laboratory for separation. The well-nigh unstable analyte was institute to be AST, with reliable quantification of this analyte requiring blood samples to be separated immediately or, if kept chilled, within 24 to 48 hours.

Only three previous studies accept investigated the stability of full general clinical chemistry analytes in claret kept unseparated beyond 24 hours. Ono et al. drew claret from 10 volunteers into obviously serum tubes and left aliquots of whole blood to stand at iv°C, 23°C, or thirty°C for up to 48 hours. 4 They found no significant change in albumin, total cholesterol, triglyceride, or full protein at 4°C or 23°C, which is in understanding with the nowadays written report. Still, they also found GGT and creatinine to be stable at these temperatures, whereas we plant them to change past 8% and 18% respectively after 48 hours at 21°C. Whilst Ono et al. plant little change in ALT and AST at 4°C, the concentrations increased significantly after 8 hours at 23°C. We found ALT to alter by merely 2% up to 48 hours at four°C and 21°C, but AST changed past 5% at iv°C and past 35% at 21°C after 48 hours. These discrepancies may reflect differences in the analytical methods used in the present study compared with those used 20 years ago past Ono et al., and the use of serum rather than plasma samples.

In another study, Hankinson et al. 5 investigated the stability of total cholesterol, HDL, apoA1, and apoB in whole blood samples taken from 12 individuals and stored at room temperature (21°C) in ambience light for up to 72 hours, or placed in a Styrofoam mailer with a frozen gel pack (which maintained a temperature of iv°C for 20 hours) for up to 48 hours. The study design was similar to that of the present written report, with whole claret samples stored under each temperature condition up to the appropriate time-point, then centrifuged, the plasma aliquoted and frozen at –eighty°C. Samples from all time-points were analysed in one belittling run. The concentrations of all of the lipids were constitute to change non-significantly in chilled blood. However, at room temperature, although total cholesterol and apoA1 inverse merely non-significantly, HDL and apoB increased past 3.0% and 5.2% per day respectively. By contrast, in the present study, HDL and apoB changed by –0.6% and +0.four% per day respectively at room temperature. The discrepancies betwixt the results of the two studies may also reflect differences in the analytical methods. Hankinson et al. measured HDL by precipitation of very depression density lipoprotein (VLDL) and LDL with dextran sulphate and magnesium chloride, apoA1 was measured in the HDL and HDL3 fractions by radial immunodiffusion and apoB measured in whole plasma by radial immunodiffusion. By dissimilarity, in the present study, the analytes were measured straight in plasma by automated methods optimized to deal with potential interference from color due to haemolysis, which becomes more of a trouble every bit the filibuster to plasma separation increases. 7 In addition, the blood samples stored at room temperature in the study by Hankinson et al. were exposed to ambient lite, which might accept afflicted stability of HDL and apoB, whereas samples in the present written report were stored in the night.

Finally, Heins et al. investigated the stability of diverse analytes in whole claret samples taken from 20 patently healthy individuals into plain serum tubes and so stored chilled (9°C) or at room temperature (23–27°C) in the dark for vii days. 6 An analyte was described equally unstable if the change in concentration was significantly greater than the maximum allowable inaccuracy co-ordinate to the Guidelines of the German Federal Medical Quango: 6% for creatinine, cholesterol, HDL, and LDL; vii% for AST, ALT, and GGT; and eight% for CK. These investigators reported ALT, AST, and cholesterol to be stable for 7 days at 9°C, and for 3 days at room temperature. By contrast, yet, we found that the mean concentration of AST inverse by more than xiv% after vii days under chilled weather condition and by over xl% afterward iii days at room temperature. Other studies have too found a substantial increase in AST, due to haemolysis and a 40-fold college activeness of AST in erythrocytes compared with serum. 8, nine Heins et al. reported HDL, LDL, CK, and GGT to be stable for vii days at 9°C, but not at 23–27°C. We also found CK to change by less than 8%, and GGT to alter by less than 7%, subsequently 7 days under chilled atmospheric condition. Moreover, in our report, HDL and LDL inverse by less than seven% after 7 days not simply under chilled conditions, but also at room temperature. Heins et al. found that creatinine concentrations increased by around twenty% at room temperature over 3 days (which agrees with the present study) but decreased by around 8% over the same period at ix°C (whereas we found less than a 4% change over 7 days under chilled conditions). Discrepancies between the results of Heins et al. and the nowadays study might exist explained by differences in analytical methods, past the means of dealing with interference from haemolysis, by differences in temperature atmospheric condition, or by the use of serum rather than plasma samples. Furthermore, Heins et al. performed biochemical measurements on the samples immediately after centrifugation at each fourth dimension-betoken, rather than freezing the samples and analysing them all in the same run, as in the present study, and then that day-to-solar day assay variability may have affected results.

Many analytes considered in the present report did showroom a slight increase in concentration over time, which agrees with a previous report. 7 This is contrary to what 1 might expect to observe from analyte degradation, and seems likely to exist due to leakage of h2o from the plasma into the blood-red cells (following failure of the sodium/potassium pump to maintain osmotic rest) resulting in swelling of red cells, increment in the haematocrit, decrease in the plasma volume and, therefore, increased concentration of plasma analytes. It has also been reported that certain analytes, specially AST, have a much higher activity in red blood cells than plasma, causing an increased concentration in haemolysed plasma. viii, ix Furthermore, it has been suggested that the increase in creatinine concentration during storage is due to non-specific formation of pseudocreatinines. 6 Recording the length of time from collection to separation of each sample might allow appropriate adjustment to be made for the slight increase in concentration of these analytes over time. The degree of change in analyte concentrations may differ slightly in a existent situation compared with a laboratory setting, equally is suggested by some of the results from Hankinson et al. v In a study involving mailed blood samples from around 20 000 individuals, cholesterol concentrations in samples that had spent 4 days in the post were an average of virtually 7% higher than in those that had spent one 24-hour interval in the post, just there was less than a 2% divergence in apoA1 levels (Clark South, Youngman LD, Parish Southward, Palmer A, Peto R, Collins R. Total cholesterol, apolipoproteins B and A1, and non-fatal myocardial infarction: 19 594 male and female cases and controls of ISIS-3. Unpublished manuscript). It should as well be noted that 'room temperature' in the present study was defined as 21°C, which may non be realistic for studies in hotter climates (and further stability studies under such weather need to be conducted). However, since many analytes were found to change by only a few per cent over at to the lowest degree seven days at 21°C, it might be supposed that any change at higher temperatures may remain in this range for at least 3 to iv days, which might yet be a feasible time-frame within which to transport whole blood samples to a fundamental facility.

In conclusion, we have shown that the concentrations of many analytes change by only a few per cent in whole blood stored at room temperature for up to vii days, and may therefore be measured reliably in mailed blood samples. These results are relevant for planning blood-based epidemiological studies. Depending upon the analytes to be measured, blood collection methods could be greatly simplified and, hence, the costs vastly reduced, enabling blood drove to be included in studies where information technology would non otherwise be considered feasible.

  • Uncomplicated blood collection methods could help make large claret-based epidemiological studies feasible.

  • The concentrations of a wide range of analytes (including lipids) may exist measured reliably in whole claret stored at room temperature for upwardly to seven days.

  • Drove of whole claret samples by mail is a simple and toll-effective mode to facilitate the inclusion of blood assays in big-scale epidemiological studies.

Table i

Assay values in samples separated immediately after collection from 12 good for you volunteers anile 25–60 years (with reference intervals)

Analyte a Hateful Standard deviation Minimum Maximum Reference interval b
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein.
bMethod-specific reference intervals established by Beckman Coulter, except for albumin, cholesterol, HDL, LDL, and triglyceride which were established in-firm from analysis of healthy individuals aged thirty–79 years in a case-control study of myocardial infarction (north = 10 074 individuals for albumin and cholesterol, n = 2912 for HDL, LDL, and triglyceride).
Albumin (g/l) 42.6 2.5 38.iii 46.nine 34–47
ALT (U/l) 18.9 5.0 xiv.0 31.2 14–63
ApoA1 (mg/dl) 156.five 31.9 81.4 209.3 95–228
ApoB (mg/dl) 87.6 21.1 55.2 113.4 51–165
AST (U/l) twenty.seven three.8 15.ii 26.8 15–41
Cholesterol (mmol/l) 5.1 1.three 2.5 vi.seven 3.7–7.seven
CK (U/l) 114.9 62.5 61.1 276.4 38–397
Creatinine (umol/l) 67.0 x.ii 52.ix 82.ane 35–106
GGT (U/l) 15.1 half-dozen.8 10.5 35.0 7–l
HDL (mmol/l) 1.half-dozen 0.5 0.7 ii.6 0.5–2.1
LDL (mmol/l) 3.0 one.0 1.7 4.5 1.5–4.iv
Protein (g/l) 72.ii 2.9 65.0 76.four 61–79
Triglyceride (mmol/l) 1.1 0.5 0.six ii.one 0.5–4.seven
Analyte a Mean Standard deviation Minimum Maximum Reference interval b
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein.
bMethod-specific reference intervals established past Beckman Coulter, except for albumin, cholesterol, HDL, LDL, and triglyceride which were established in-house from assay of good for you individuals anile 30–79 years in a case-command study of myocardial infarction (n = ten 074 individuals for albumin and cholesterol, n = 2912 for HDL, LDL, and triglyceride).
Albumin (chiliad/l) 42.six ii.v 38.3 46.9 34–47
ALT (U/50) 18.9 5.0 14.0 31.ii 14–63
ApoA1 (mg/dl) 156.5 31.9 81.four 209.3 95–228
ApoB (mg/dl) 87.half dozen 21.1 55.2 113.4 51–165
AST (U/l) twenty.seven 3.8 15.2 26.eight 15–41
Cholesterol (mmol/fifty) 5.1 i.3 2.5 6.vii 3.seven–vii.7
CK (U/fifty) 114.9 62.5 61.1 276.4 38–397
Creatinine (umol/l) 67.0 ten.2 52.9 82.1 35–106
GGT (U/l) xv.1 half dozen.8 10.5 35.0 vii–50
HDL (mmol/l) one.vi 0.five 0.7 two.half-dozen 0.five–2.1
LDL (mmol/l) iii.0 1.0 1.7 4.5 one.5–4.4
Protein (k/l) 72.2 2.ix 65.0 76.4 61–79
Triglyceride (mmol/fifty) 1.one 0.5 0.6 2.i 0.5–iv.7

Table i

Assay values in samples separated immediately after drove from 12 salubrious volunteers aged 25–sixty years (with reference intervals)

Analyte a Mean Standard deviation Minimum Maximum Reference interval b
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein.
bMethod-specific reference intervals established by Beckman Coulter, except for albumin, cholesterol, HDL, LDL, and triglyceride which were established in-house from assay of healthy individuals aged 30–79 years in a instance-control study of myocardial infarction (due north = ten 074 individuals for albumin and cholesterol, n = 2912 for HDL, LDL, and triglyceride).
Albumin (g/fifty) 42.half dozen 2.v 38.3 46.ix 34–47
ALT (U/l) 18.9 5.0 xiv.0 31.two 14–63
ApoA1 (mg/dl) 156.5 31.9 81.iv 209.3 95–228
ApoB (mg/dl) 87.half dozen 21.i 55.2 113.4 51–165
AST (U/fifty) 20.7 3.viii 15.ii 26.8 fifteen–41
Cholesterol (mmol/l) 5.1 ane.iii 2.5 6.seven three.seven–7.7
CK (U/l) 114.ix 62.v 61.1 276.iv 38–397
Creatinine (umol/l) 67.0 10.2 52.9 82.i 35–106
GGT (U/fifty) 15.1 6.8 ten.v 35.0 seven–l
HDL (mmol/l) i.6 0.5 0.seven 2.6 0.5–two.1
LDL (mmol/l) 3.0 one.0 1.7 4.5 i.5–4.4
Protein (yard/fifty) 72.2 2.9 65.0 76.4 61–79
Triglyceride (mmol/fifty) one.1 0.v 0.6 ii.ane 0.5–4.7
Analyte a Mean Standard deviation Minimum Maximum Reference interval b
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein.
bMethod-specific reference intervals established by Beckman Coulter, except for albumin, cholesterol, HDL, LDL, and triglyceride which were established in-firm from analysis of good for you individuals anile xxx–79 years in a case-command written report of myocardial infarction (due north = x 074 individuals for albumin and cholesterol, n = 2912 for HDL, LDL, and triglyceride).
Albumin (chiliad/l) 42.6 ii.five 38.3 46.9 34–47
ALT (U/l) 18.9 5.0 14.0 31.2 xiv–63
ApoA1 (mg/dl) 156.five 31.ix 81.4 209.3 95–228
ApoB (mg/dl) 87.6 21.i 55.2 113.4 51–165
AST (U/l) xx.7 three.8 15.2 26.viii 15–41
Cholesterol (mmol/l) 5.1 1.3 two.five 6.7 3.seven–7.vii
CK (U/l) 114.9 62.5 61.one 276.4 38–397
Creatinine (umol/l) 67.0 10.2 52.9 82.1 35–106
GGT (U/fifty) 15.one half dozen.eight 10.5 35.0 7–50
HDL (mmol/l) 1.half-dozen 0.five 0.7 2.6 0.5–2.1
LDL (mmol/l) three.0 1.0 1.vii four.v 1.5–4.4
Protein (yard/l) 72.two two.9 65.0 76.4 61–79
Triglyceride (mmol/l) one.ane 0.5 0.6 ii.1 0.5–iv.7

Tabular array 2

Percentage change in analyte concentration over time in samples stored at 21°C and four°C

% change from immediately separated samples (SEM)
Analyte a Temp ane day 2 days 3 days 4 days 7 days P value tendency P value 21°C 5 iv°C
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein; SEM, standard error of the mean.
bOR, outside range for the analyte.
Albumin 21°C 1.half dozen (1.0) 1.four (1.0) one.7 (0.7) 1.three (0.v) 3.4 (1.0) <0.0001 0.four
4°C 1.4 (1.1) 2.2 (0.6) 1.3 (0.7) 2.1 (0.vii) 3.eight (0.5) <0.0001
ALT 21°C 1.0 (1.eight) ii.2 (two.0) 5.three (1.6) 9.one (4.3) ORb 0.001 <0.0001
iv°C –0.5 (1.2) 1.4 (one.seven) 0.nine (1.4) 2.2 (1.vii) –two.7 (one.3) 0.4
ApoA1 21°C 2.7 (1.1) 0.8 (1.1) ii.1 (1.1) 0.6 (1.0) ane.vi (i.1) 0.7 0.08
iv°C 1.8 (one.0) 3.7 (0.8) 1.vi (1.iii) 2.2 (0.seven) 2.viii (0.6) 0.02
ApoB 21°C 3.8 (1.2) 1.0 (1.6) 2.viii (1.4) 2.1 (i.3) 3.v (0.nine) 0.02 0.6
4°C 1.viii (1.7) 3.3 (1.0) ii.5 (1.0) ii.ane (0.6) four.3 (0.seven) 0.003
AST 21°C xv.ii (three.0) 35.3 (4.2) 40.5 (5.3) 34.4 (7.7) ORb <0.0001 <0.0001
4°C ane.5 (1.ix) 5.3 (1.0) 7.9 (1.5) 7.9 (1.three) 14.6 (2.6) <0.0001
Cholesterol 21°C one.five (i.three) –0.0 (1.4) –0.6 (1.0) –0.eight (0.viii) –1.1 (1.three) 0.03 0.0003
4°C 0.seven (ane.iv) two.2 (0.8) 0.6 (0.9) 1.2 (1.i) two.1 (0.six) 0.03
CK 21°C –0.vii (1.two) –viii.viii (1.half-dozen) –ix.9 (1.3) –eleven.2 (i.4) –fifteen.7 (ii.0) <0.0001 <0.0001
4°C 3.0 (i.3) 3.5 (0.9) 1.9 (one.3) 2.3 (one.ane) 4.0 (1.one) 0.0008
Creatinine 21°C six.7 (1.2) 18.ane (1.5) 21.1 (1.two) 24.v (i.7) 42.5 (4.3) <0.0001 <0.0001
4°C 0.5 (1.0) 0.8 (1.1) 0.vii (1.0) –0.0 (ane.one) 3.8 (1.0) 0.5
GGT 21°C two.0 (two.seven) seven.9 (2.3) eleven.3 (3.2) thirteen.vii (three.three) ten.4 (2.2) <0.0001 <0.0001
4°C 0.ane (2.2) 1.4 (2.seven) 2.vii (two.0) 0.0 (1.5) 2.0 (ane.9) 0.9
HDL 21°C –i.2 (1.4) –3.iv (1.1) –3.9 (i.4) –two.9 (1.0) –3.6 (one.ix) <0.0001 0.ii
4°C –0.v (1.8) –0.two (ane.0) –three.3 (0.eight) –i.4 (ane.0) –iii.6 (0.9) 0.005
LDL 21°C 4.8 (ane.4) 5.4 (1.half-dozen) half dozen.7 (1.6) 6.two (i.2) 5.vii (2.ane) <0.0001 0.one
iv°C 1.6 (one.4) two.8 (0.7) 2.6 (0.8) 3.6 (0.9) half dozen.9 (0.seven) 0.0002
Protein 21°C 2.five (ane.ii) ane.v (1.4) i.8 (1.1) ane.2 (0.6) i.4 (ane.1) 0.iv 0.2
iv°C 2.2 (1.ii) 1.9 (0.eight) 1.6 (1.1) 1.9 (0.8) 2.eight (0.6) 0.03
Triglyceride 21°C 0.eight (two.2) ii.2 (one.5) ane.4 (1.7) ane.6 (i.8) 0.two (2.4) 0.half-dozen 0.5
4°C 0.4 (1.8) 0.half-dozen (1.5) –3.2 (1.nine) –0.vii (1.9) 1.9 (1.1) 0.8
% change from immediately separated samples (SEM)
Analyte a Temp 1 solar day 2 days 3 days 4 days 7 days P value trend P value 21°C v 4°C
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, loftier density lipoprotein; LDL, low density lipoprotein; SEM, standard error of the mean.
bOR, outside range for the analyte.
Albumin 21°C ane.half-dozen (1.0) 1.4 (1.0) 1.7 (0.7) 1.iii (0.5) 3.4 (one.0) <0.0001 0.4
4°C 1.4 (one.i) 2.two (0.6) ane.3 (0.7) two.i (0.vii) three.8 (0.v) <0.0001
ALT 21°C i.0 (1.8) 2.2 (2.0) 5.3 (1.six) 9.one (4.3) ORb 0.001 <0.0001
4°C –0.5 (1.2) 1.4 (1.7) 0.nine (1.4) 2.2 (1.seven) –ii.7 (one.3) 0.4
ApoA1 21°C 2.7 (one.1) 0.viii (1.ane) 2.1 (ane.one) 0.6 (ane.0) ane.half-dozen (ane.1) 0.7 0.08
iv°C i.8 (1.0) three.7 (0.8) 1.half dozen (ane.3) 2.2 (0.7) two.8 (0.6) 0.02
ApoB 21°C three.viii (ane.ii) i.0 (1.six) 2.eight (1.four) ii.ane (1.3) 3.v (0.9) 0.02 0.6
4°C one.8 (1.seven) 3.iii (one.0) 2.5 (1.0) 2.1 (0.6) 4.3 (0.7) 0.003
AST 21°C fifteen.2 (3.0) 35.3 (four.2) forty.5 (5.3) 34.4 (7.7) ORb <0.0001 <0.0001
4°C ane.5 (1.9) 5.3 (1.0) 7.ix (1.v) 7.9 (one.3) 14.vi (ii.6) <0.0001
Cholesterol 21°C 1.5 (i.three) –0.0 (ane.four) –0.vi (ane.0) –0.8 (0.eight) –1.ane (1.iii) 0.03 0.0003
four°C 0.7 (1.four) two.ii (0.8) 0.6 (0.9) 1.ii (1.1) 2.i (0.6) 0.03
CK 21°C –0.7 (ane.2) –8.8 (1.vi) –9.nine (ane.3) –eleven.two (1.4) –15.7 (2.0) <0.0001 <0.0001
4°C 3.0 (i.3) 3.5 (0.ix) 1.9 (ane.3) two.3 (1.1) 4.0 (1.1) 0.0008
Creatinine 21°C 6.7 (1.2) 18.1 (1.5) 21.1 (1.2) 24.5 (i.7) 42.five (4.three) <0.0001 <0.0001
4°C 0.5 (1.0) 0.8 (one.1) 0.seven (i.0) –0.0 (1.ane) 3.8 (i.0) 0.5
GGT 21°C 2.0 (2.7) seven.ix (2.iii) xi.3 (3.two) thirteen.seven (3.3) 10.four (two.ii) <0.0001 <0.0001
4°C 0.i (2.2) one.4 (2.7) 2.vii (2.0) 0.0 (1.5) 2.0 (1.nine) 0.9
HDL 21°C –1.2 (1.4) –iii.iv (1.1) –iii.ix (1.four) –2.9 (1.0) –3.6 (ane.ix) <0.0001 0.2
4°C –0.v (1.8) –0.2 (1.0) –3.3 (0.eight) –1.four (1.0) –3.half-dozen (0.9) 0.005
LDL 21°C 4.viii (1.4) 5.4 (ane.6) six.7 (i.6) 6.2 (1.2) 5.seven (2.one) <0.0001 0.1
4°C 1.6 (1.4) 2.8 (0.vii) ii.6 (0.8) iii.half dozen (0.9) half-dozen.nine (0.7) 0.0002
Poly peptide 21°C 2.v (1.two) 1.5 (1.4) 1.8 (ane.1) 1.2 (0.six) 1.iv (1.1) 0.4 0.ii
4°C two.2 (ane.2) 1.nine (0.viii) one.6 (1.ane) i.9 (0.8) ii.8 (0.6) 0.03
Triglyceride 21°C 0.8 (2.2) 2.2 (1.5) 1.4 (i.seven) one.6 (ane.eight) 0.2 (two.4) 0.6 0.5
4°C 0.4 (ane.viii) 0.six (1.five) –3.2 (1.9) –0.7 (1.ix) one.9 (1.1) 0.eight

Table 2

Percentage modify in analyte concentration over time in samples stored at 21°C and 4°C

% change from immediately separated samples (SEM)
Analyte a Temp 1 day ii days 3 days 4 days seven days P value trend P value 21°C v 4°C
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, low density lipoprotein; SEM, standard fault of the mean.
bOR, outside range for the analyte.
Albumin 21°C 1.6 (one.0) 1.4 (1.0) 1.7 (0.7) one.3 (0.v) 3.4 (1.0) <0.0001 0.4
4°C ane.4 (one.1) 2.2 (0.6) 1.3 (0.7) 2.one (0.7) 3.viii (0.5) <0.0001
ALT 21°C 1.0 (ane.8) 2.2 (2.0) 5.3 (one.vi) 9.1 (4.3) ORb 0.001 <0.0001
4°C –0.5 (1.2) i.4 (1.7) 0.9 (1.4) ii.two (1.seven) –2.seven (1.iii) 0.4
ApoA1 21°C ii.7 (ane.1) 0.8 (i.ane) ii.1 (1.one) 0.half-dozen (ane.0) one.vi (ane.i) 0.7 0.08
iv°C i.8 (1.0) 3.vii (0.viii) i.6 (1.three) 2.2 (0.7) 2.8 (0.6) 0.02
ApoB 21°C 3.viii (one.ii) ane.0 (1.half-dozen) 2.8 (one.4) 2.ane (1.3) 3.five (0.9) 0.02 0.half dozen
4°C ane.8 (1.7) iii.3 (one.0) 2.5 (i.0) 2.1 (0.half-dozen) four.3 (0.vii) 0.003
AST 21°C 15.ii (3.0) 35.3 (4.2) forty.5 (5.3) 34.4 (7.vii) ORb <0.0001 <0.0001
4°C 1.5 (1.9) five.three (1.0) seven.9 (1.five) 7.9 (1.3) 14.half dozen (two.vi) <0.0001
Cholesterol 21°C 1.5 (i.3) –0.0 (ane.4) –0.6 (ane.0) –0.8 (0.viii) –ane.1 (one.3) 0.03 0.0003
4°C 0.vii (one.iv) ii.2 (0.8) 0.half dozen (0.9) 1.2 (1.1) two.1 (0.6) 0.03
CK 21°C –0.7 (1.2) –viii.8 (1.vi) –9.ix (1.3) –11.2 (ane.four) –15.7 (two.0) <0.0001 <0.0001
four°C 3.0 (one.3) 3.5 (0.9) 1.9 (1.3) two.3 (ane.1) 4.0 (i.1) 0.0008
Creatinine 21°C half dozen.7 (1.2) 18.ane (i.v) 21.i (i.2) 24.5 (1.vii) 42.v (4.three) <0.0001 <0.0001
4°C 0.5 (one.0) 0.8 (1.1) 0.7 (1.0) –0.0 (1.1) 3.8 (ane.0) 0.5
GGT 21°C 2.0 (2.7) 7.9 (two.three) xi.3 (3.2) 13.7 (iii.three) ten.iv (2.2) <0.0001 <0.0001
4°C 0.one (ii.2) 1.4 (2.7) 2.vii (ii.0) 0.0 (1.5) 2.0 (i.9) 0.ix
HDL 21°C –one.2 (one.4) –3.iv (i.ane) –iii.ix (1.four) –ii.9 (i.0) –3.6 (i.9) <0.0001 0.2
four°C –0.5 (ane.8) –0.two (1.0) –3.3 (0.8) –1.iv (1.0) –3.6 (0.9) 0.005
LDL 21°C four.8 (one.iv) v.iv (1.6) 6.vii (1.half-dozen) 6.two (1.2) 5.7 (2.1) <0.0001 0.i
iv°C 1.half-dozen (ane.4) 2.viii (0.7) two.6 (0.viii) three.6 (0.nine) 6.9 (0.7) 0.0002
Protein 21°C 2.v (one.two) 1.v (i.four) one.viii (ane.one) 1.2 (0.6) 1.iv (one.i) 0.4 0.ii
four°C ii.2 (1.ii) 1.9 (0.viii) i.6 (one.1) 1.ix (0.8) ii.viii (0.half dozen) 0.03
Triglyceride 21°C 0.8 (2.2) 2.2 (1.v) one.4 (ane.7) 1.6 (1.8) 0.2 (ii.4) 0.half-dozen 0.5
four°C 0.four (1.8) 0.6 (1.5) –3.2 (1.nine) –0.7 (ane.ix) 1.ix (i.ane) 0.8
% modify from immediately separated samples (SEM)
Analyte a Temp 1 day 2 days 3 days 4 days 7 days P value trend P value 21°C v iv°C
aALT, alanine transaminase; apoA1, apolipoprotein A1; apoB, apolipoprotein B; AST, aspartate transaminase; CK, creatine kinase; GGT, γ-glutamyl transferase; HDL, high density lipoprotein; LDL, depression density lipoprotein; SEM, standard error of the hateful.
bOR, exterior range for the analyte.
Albumin 21°C 1.6 (i.0) 1.iv (i.0) 1.seven (0.vii) 1.iii (0.5) 3.4 (i.0) <0.0001 0.4
4°C ane.4 (ane.ane) 2.2 (0.half-dozen) 1.3 (0.7) 2.1 (0.7) 3.8 (0.five) <0.0001
ALT 21°C i.0 (1.8) 2.2 (2.0) 5.3 (1.6) 9.ane (iv.3) ORb 0.001 <0.0001
4°C –0.five (i.2) 1.4 (1.vii) 0.ix (i.4) 2.two (1.7) –two.7 (1.iii) 0.4
ApoA1 21°C 2.7 (i.i) 0.8 (1.1) 2.1 (1.one) 0.6 (ane.0) i.6 (1.1) 0.vii 0.08
4°C 1.viii (1.0) 3.7 (0.viii) one.half dozen (ane.3) 2.2 (0.7) 2.viii (0.6) 0.02
ApoB 21°C iii.8 (1.2) one.0 (i.6) ii.viii (1.4) 2.one (1.3) 3.5 (0.ix) 0.02 0.6
four°C 1.8 (1.vii) three.3 (1.0) 2.five (1.0) two.1 (0.half-dozen) iv.3 (0.7) 0.003
AST 21°C 15.two (3.0) 35.3 (iv.2) 40.5 (five.3) 34.iv (7.7) ORb <0.0001 <0.0001
four°C 1.5 (i.nine) v.iii (1.0) seven.9 (one.5) 7.nine (1.iii) 14.6 (ii.half-dozen) <0.0001
Cholesterol 21°C one.five (1.3) –0.0 (ane.four) –0.6 (1.0) –0.eight (0.8) –1.1 (i.3) 0.03 0.0003
iv°C 0.7 (i.4) 2.ii (0.8) 0.6 (0.ix) 1.two (ane.1) two.1 (0.6) 0.03
CK 21°C –0.seven (i.two) –8.viii (one.half dozen) –9.9 (1.3) –11.ii (ane.four) –15.7 (2.0) <0.0001 <0.0001
4°C 3.0 (1.three) 3.v (0.9) 1.9 (1.iii) two.3 (one.1) 4.0 (1.i) 0.0008
Creatinine 21°C 6.7 (1.2) 18.1 (1.5) 21.1 (i.2) 24.5 (1.7) 42.5 (4.3) <0.0001 <0.0001
4°C 0.5 (1.0) 0.eight (ane.1) 0.seven (1.0) –0.0 (1.1) 3.viii (one.0) 0.5
GGT 21°C 2.0 (2.7) 7.ix (two.3) eleven.3 (3.2) 13.7 (three.iii) ten.4 (2.2) <0.0001 <0.0001
4°C 0.1 (2.two) one.4 (ii.7) 2.seven (two.0) 0.0 (1.5) ii.0 (1.nine) 0.nine
HDL 21°C –i.ii (1.four) –three.4 (1.i) –3.9 (one.4) –2.9 (one.0) –3.6 (ane.9) <0.0001 0.2
4°C –0.5 (one.viii) –0.2 (1.0) –iii.three (0.8) –1.four (1.0) –3.half-dozen (0.nine) 0.005
LDL 21°C iv.viii (1.4) 5.4 (1.6) half-dozen.seven (1.6) half dozen.2 (1.2) v.vii (2.1) <0.0001 0.1
4°C 1.vi (1.four) ii.8 (0.vii) 2.6 (0.8) 3.6 (0.9) 6.nine (0.7) 0.0002
Protein 21°C 2.five (one.2) ane.5 (1.4) i.8 (ane.1) i.2 (0.vi) one.4 (one.ane) 0.4 0.2
4°C 2.2 (i.2) ane.9 (0.8) i.half-dozen (1.1) 1.nine (0.8) ii.viii (0.half dozen) 0.03
Triglyceride 21°C 0.8 (2.2) 2.2 (1.5) 1.iv (1.7) 1.half-dozen (1.8) 0.ii (2.4) 0.vi 0.five
four°C 0.4 (ane.8) 0.6 (1.5) –3.2 (i.9) –0.7 (1.9) i.ix (1.1) 0.viii

Figure 1

Percentage change per day (95% CI) for analytes in whole blood samples stored at 21°C or 4°C for up to 7 days

Percentage change per twenty-four hour period (95% CI) for analytes in whole blood samples stored at 21°C or iv°C for up to vii days

Effigy one

Percentage change per day (95% CI) for analytes in whole blood samples stored at 21°C or 4°C for up to 7 days

Percentage change per solar day (95% CI) for analytes in whole claret samples stored at 21°C or 4°C for up to vii days

This work was supported by the Medical Research Council, the British Heart Foundation and Cancer Research UK. We gratefully acknowledge Mary Bradley, Tatyana Chavagnon, Buki Chukwurah, Kathy Emmens, Joanne Gordon, Joy Hill, Meng Jie Ji, Karen Kourellias, Stuart Norris, Leon Peto, Martin Radley, Janet Taylor, Jane Wintour, and Marie Yeung of the Clinical Trial Service Unit of measurement and Epidemiological Studies Unit (CTSU) laboratories. Dr Robert Clarke provided helpful comments on the manuscript.

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