Which evacuated tube is used for cholesterol testing

From this point of view, the A brand tubes were and remain of a high quality. All the ellipses of the A brand tubes are above the green rectangle in Figure 1. The same is true for the tubes F, which are of the same manufacturer.

This example demonstrates that an adequate draw volume does not yet ensure the adequate anticoagulant concentration as far as the H1-A5 is concerned. The tubes were obviously produced following an older DIN ISO standard, for which the anticoagulant concentration 6.

The characteristics of these tubes clearly contrast those of the tubes B and C, as the figures in the continuation demonstrate. Previously the ellipses were much larger, and they exceeded the upper anticoagulant concentration limit even with the draw volumes very close to the nominal 3 mL mark.

The ellipses in blue are small and remain within the green rectangle during the whole shelf life; nevertheless it has to be mentioned the shelf life was at the time of purchase much shorter than in the A brand tubes. The C brand tubes exhibit a good repeatability of the product; however, the anticoagulant concentration starts exceeding slightly the higher-anticoagulant concentration limit already with the draw volumes approaching 2.

The product repeatability of the D brand tubes is good, but the anticoagulant concentration starts exceeding the upper limit already approximately days before the expiration date and with the draw volumes falling below 2. This study confirmed that a control of a draw volume is not the main quality issue and does not ensure that the anticoagulant concentration is adequate.

Only in four cases, the draw volumes below the 2. On the other hand, in more than 20 cases, the anticoagulant concentration limit as set by the H1-A5 standard was exceeded at the draw volumes in the recommended range. It also needs to be mentioned that if the draw-volume inspection relays on the label mark a judgment can be false. During our first study, we found out that only one brand of the tubes had a label positioned precisely; in all others the indicators on the tube were misleading.

Easy-to-perform testing procedures as we used here which do not require blood samples can as a precautious measure ensure that the tubes are used only if they are of the adequate quality and their quality does not fluctuate too much during the time. It can alert a laboratory when it would be advisable to perform a much more complex and time-demanding verification study on blood samples.

In this section, we explain the changes in a behavior of the tubes during their shelf life. The lower the internal pressure, and the higher the difference to the external pressure, the higher a drawing capability. The tubes of different brands differ in their drawing capability and, in a way, how it reduces during the time, as Figure 5 demonstrates.

No container is entirely tight and leaks to some extent. The conditions to which the tubes were exposed or under which they were stored contribute. The tubes of the same lot would behave differently in different circumstances. Drawing capability of the tubes reduces continuously during their shelf life. Even though tubes are of a high quality, are purchased at the same time, and are of the same lot, they are not all the same if used during their shelf life.

A reduction in a drawing capacity results in a diminished draw volume and enhanced anticoagulant concentration. The outcomes might vary and can be influenced by a choice of a group of individuals, its representativeness, a normality of a distribution of the investigated parameter, and the sources of uncertainty originating from the whole procedure, comprising pre-analytical, analytical, and post-analytical phases.

All these factors can influence the conclusions of a paired t-test or ANOVA, a difference between two brands, or lots of the tubes might turn out insignificant. If the evaluation is repeated later, one can know how comparable are the examined tubes entering the process. If a difference between the results obtained for the tubes of different brands is confirmed to be statistically significant by the tests performed on blood samples, they are frequently considered not clinically important.

However, variations, which are not important on the level of a group of individuals, might reflect differently when a single person is concerned. Personal variations in blood parameters are narrower than variations on the level of a population.

It is not possible to perform validation study with blood samples for each individual, but it is easily possible to perform a quality control of the tubes which are used for personal profiles. Hence, some parameters, e.

Sample storage conditions and treatment and the choice of an analyzer are considered the contributing factors [ 21 ]. It was proven that during a training season hemoglobin and hematocrit reduce in their value, and reticulocytes do as well but independently. The pattern is general but the size of a change is sport?

It was recognized that reliable reference ranges in sportsmen could not be defined without the best laboratory practices [ 22 ].

Not univocal and entirely clear outcomes of different studies on the stability of the blood variables raise concerns and request for more clearly defined characteristics, procedures, threshold limits, personal reference ranges, and criteria for recognizing abnormalities to prevent false convictions in athletes [ 23 ]. In order to raise awareness to which extent different pre-analytical phases could affect the outcomes of hematological and biochemical tests on which sports medicine depends in following athletes, different pre-analytical aspects and the choice of anticoagulant, instabilities of some molecules were addressed to prevent misinterpretation of data and improve the usefulness of results [ 24 ].

Specimen homogenization as a pre-analytical phase received special attention [ 25 ]. They are thoroughly explained in the continuation. A methodology for a quality evaluation of evacuated blood-collection tubes for hematological tests consists of two successive measurements, a measurement of a draw volume and electrolytic conductivity, from which one can predict the anticoagulant concentration in a blood sample.

No patient- or person-related samples are required. A medium for the tests is purified water. Only low-cost equipment, a Bang burette and a field conductivity meter, is used. One also needs to know an ambient temperature and a non-reduced pressure for a period during which measurements were performed.

The latter can be obtained from a local meteorological institution on request, and temperature is easy to measure. We explain the testing procedures in full details in the following section. We previously published the nomograms for K 2 EDTA and K 3 EDTA tubes with nominal 3 mL draw volume, which enable a prediction on how is an anticoagulant concentration going to rise with a diminishing draw volume that happens during the time because of the aging of the tubes [ 7 ]. The points are the results of the quality evaluation of the tubes of two different brands, E and G, at the particular moment in time.

If the tubes in a lot are of a homogenous quality and they are going to be tested later during their shelf life, the anticoagulant concentration as expected for blood samples is going to rise as the curves indicate. In such a case, a draw-volume measurement can already give an insight into the quality of the examined tubes. A nomogram for a prediction on how is the anticoagulant concentration in 2 mL K 3 EDTA tubes of two different brands E, G going to change with a declining draw volume; green rectangle outlines the characteristics considered acceptable by H1-A5 standard [ 5 ].

If we take the G tubes as an example, for the great majority of the tested tubes, with a draw volume close to 2. If we assume that later in time we find out that the draw volume has fallen to 1. A green rectangle indicates the limits set by H1-A5 standard [ 5 ], demonstrating that the tubes would still have been of adequate quality. Skills needed to perform the tests are not difficult to master, and a laboratory or medical staff can easily develop them.

The quality of the tubes does not deteriorate very rapidly. It is important to test tubes when they are put into use, and later only occasionally, but at regular intervals. Since the tests are not time-consuming and not performed in high numbers, this additional workload does not represent an important additional burden for personnel; however, the benefits for an institution are obvious and important. An institution implementing a quality evaluation scheme always has an adequate insight into the characteristics and quality of the tubes it is using.

It can ensure that the tubes are used only if and only until they are of adequate quality or it can use the data in medical and clinical studies to test possible correlations or covariations.

A setup for a draw-volume measurement left and a conductivity cell for the anticoagulant concentration estimation right. In the schematic Figure 7 , far left, an evacuated tube, characterized by an internal pressure p int and an internal tube volume V tube , defining a conserved energy of withdrawal for a blood specimen collection is depicted.

In the middle, a draw-volume measurement is schematically represented. A starting point is a Bang burette filled with purified water to the 0 mL mark. A tip of the burette is attached to a flexible tubing, which is at the other end connected to a blood-collection device.

This part too is entirely filled with purified water. When we attach an evacuated tube to the venipuncture device, the tube starts filling with water, and consequently the water level in the Bang burette starts falling. The rising water level in the tube acts as a moving piston, reducing the void volume and causing the internal pressure to rise until it equals the external pressure p ext. At this moment, the withdrawing ends, and we can read the draw volume from a burette.

Hence, the external pressure and temperature T affect a draw-volume test. The external pressure depends on the altitude and current weather conditions and can be obtained from the local meteorological institution. The ambient temperature is also important and has to be taken into account. It affects the internal pressure in a tube at the instant of the draw-volume measurement.

For the 3 mL tubes, this means that the draw volumes between 2. Even though the standards [ 3 , 4 ] expose as the main quality issue in a nonconformity of a draw volume with the requirements, our results in Section 2 prove that a draw volume within the acceptable range does not necessarily ensure the correct anticoagulant level.

An additional insight into this aspect of quality is necessary. In other words, conductance G of a solution reflects an overall ionic composition, but, if a solution contains only a single salt, as it is a case for K 2 EDTA and K 3 EDTA tubes, it can provide an insight into a salt concentration.

A conductance depends on the geometry of a conductivity cell. A cell we used is depicted in Figure 7 far right. It was an immersive four-electrode cell, not directly applicable to our needs. We closed the bottom of the cave with a parafilm and the hole at the right with a stopper made of a pipette tip to transform it into a conductivity cell applicable for conductance measurements in solutions of a small volume.

The conductance measurement is affected by a size of electrodes and a distance between them; a cell geometry is reflected in a cell constant K. Another concern is a temperature during a measurement; it also affects the conductance value. At higher temperatures, a conductance is higher.

This is taken into account by reporting an ionic conductivity at a selected reference temperature, e. Measurements obtained at an ambient temperature are transformed into the values as would have been at the reference temperature by taking a temperature compensation into account.

In our case, the values confirmed experimentally were 1. Conductivity measurements are in fact easy to perform. A conductivity cell has a temperature sensor incorporated. We select the reference temperature, define a temperature compensation factor and a cell constant, and perform measurements. For a solution of a single salt, electrolytic conductivity values are easy to transform into a salt amount concentration, c.

If one prepares a set of the solutions with the known salt concentrations and determines their electrolytic conductivity at the reference temperature, one can relate the two parameters by depicting a graph, with the first parameter on the abscise axis, and the second on the ordinate, defining a trend line 3 :. The symbols, a and b , are the parameter of the linear equation; a stands for the intercept and b for the slope. As already explained, the draw volume had to be corrected to obtain an estimation of a blood sample volume; a concentration is volume dependent, and therefore it has to be corrected too, to correctly represent the anticoagulant concentration as expected after a blood specimen collection 5 :.

Draw volume and anticoagulant concentration determination can be implemented into laboratory quality control routines. If followed during the time in a form of control charts, they can ensure that the tubes are used only if and only until they are of adequate quality. The same testing procedure for a draw-volume measurement is applicable also to citrate tubes. However, in terms of a determination of the anticoagulant concentration, this is a distinct case. The reason is that citrate in the tubes can be either buffered or unbuffered.

As a result, a solution after a draw-volume test can have quite a different pH and contains different citrate equilibrium forms in different proportions.

For this reason measurement of electrolytic conductivity cannot be used here, and an adequate low-cost and easy-to-perform testing procedure yet has to be developed.

We evaluated the citrate tubes of two different brands, A and B. Both were type tubes but differed in nominal draw volumes, which were 4. Measured draw volumes that we obtained were 4. Getting insight into the composition of the anticoagulant solution after a draw-volume test is possible, but the approach is complex and time-consuming. The most commonly used blood collection tubes. Gel separates serum from cells. Chemistry, serology, immunology Green Sodium or lithium heparin with or without gel Prevents clotting by inhibiting thrombin and thromboplastin Stat and routine chemistry Lavender or pink Potassium EDTA Prevents clotting by binding calcium Hematology and blood bank Gray Sodium fluoride, and sodium or potassium oxalate Fluoride inhibits glycolysis, and oxalate prevents clotting by precipitating calcium.

Glucose especially when testing will be delayed , blood alcohol, lactic acid. Blood Collection Tubes. How to Subscribe. Need multiple seats for your university or lab? Get a quote.