Reconstituting Lyophilised Controls
What is Lyophilisation?
Lyophilisation or ‘freeze drying’ is the process by which water is removed from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase. The process consists of three separate processes:
- Primary Drying (Sublimation)
- Secondary Drying (Desorption)
There are many benefits to using a lyophilised control including; improved product shelf-life and enhanced stability of volatile analytes. For example, many lyophilised controls have a shelf life of up to four years from the date of manufacture resulting in a reduction of costly new lot validation studies. Furthermore, lyophilised controls can be aliquoted and refrozen to extend the working stability of the product.
Reconstituting Lyophilised QC Material
The process of reconstitution involves adding a specified volume of distilled water to lyophilised QC material. The water should completely dissolve the lyophilised contents, giving a liquid solution, which is ready for analysis.
Reconstitution is a straightforward process, but requires a high level of precision. Small errors can have serious implications to the reconstituted material:
- If too much water is pipetted during reconstitution, the material will be heavily diluted and results will be lower than expected
- If too little water is pipetted during reconstitution, the material will not be sufficiently diluted, and results will be higher than expected
- If the correct volume of water is pipetted, but a small amount of water gets stuck in the pipette tip due to poor pipetting technique, results will be higher than expected
If a lyophilised control has been reconstituted incorrectly the contents of the vial will be wasted. It is therefore vitally important that controls are reconstituted with care.
Materials and Methods Required
The list of requirements for an accurate and consistent reconstitution technique is not extensive, but each requirement is vital. Labs should have:
- Calibrated volumetric pipettes
- Sterile, appropriately sized pipette tips
- Distilled water, or other reconstitution fluid as specified
- Technician with good pipetting technique
- Lyophilised QC stored according to manufacturer’s specifications
How to Reconstitute Lyophilised QC Material
Each different lyophilised control may require slightly different preparation, always refer to the instructions for use before reconstituting control material. The below guide provides a general overview of the reconstitution process, using the Randox Human Assayed Chemistry Premium Plus control (HN1530) as an example
- Place the vial of lyophilised QC on a flat surface, carefully remove the lid and the rubber stopper making sure not to spill any material
- Using a calibrated pipette and sterilised pipette tip, add exactly 5ml of distilled water directly into the QC vial, ensuring no water is left in the pipette tip, or on the rim/side of the vial
- Place the rubber stopper and lid firmly back onto the QC vial, and leave to stand for 30 minutes
- After 30 minutes, gently invert the QC vial 10-15 times to ensure the contents is completely dissolved, making sure to avoid the formation of foam. It is important that you DO NOT SHAKE the vial. Alternatively place the vial on a roller for 30 minutes to ensure the contents is thoroughly mixed
- Once satisfied all material has been completely dissolved, proceed to use the QC product in accordance with the ‘Control’ section of the individual analyser application
- Once finished, refrigerate any unused material. It is good practice to label the vial with the date of reconstitution to prevent the use of material outside of the recommended stability period
- Prior to reusing lyophilised material, mix the contents thoroughly by gentle inversion, as highlighted in Step 4
It is important to remember that there may be slightly different reconstitution requirements for different QC material. For this reason, it is vital that the instructions provided on the QC Kit Inserts are closely followed.
Reconstituting lyophilised QC can be time-consuming. Therefore, Randox Acusera offer convenient 5ml distilled water serum diluent to assist laboratories with reconstitution of lyophilised controls. These user-friendly pour over vials streamline the reconstitution process and eliminate the risk of pipetting errors.
If you have any further questions regarding lyophilised controls or would like to contact us, please do so by emailing us at firstname.lastname@example.org or use the contact us button provided.
Some laboratory professionals believe that using Internal Quality Control (IQC) and External Quality Assurance (EQA, also known as Proficiency Testing) material from the same provider can lead to increased levels of qc bias, or that their test system will not be appropriately challenged. It is important to address these concerns, because some labs may in fact be hindering their own performance by using IQC and EQA material from different sources.
It is important to first understand how IQC and EQA work together to help form a complete Laboratory Quality Management System.
IQC and EQA in Laboratory Quality Management
IQC is a means of monitoring test system precision on a daily basis. IQC effectively evaluates test system performance over time, so that any sudden or gradual shifts in performance can be detected. However, while IQC is an effective performance monitor, it cannot detect more intricate problems like calibration errors or wide acceptable limits provided by some QC manufacturers.
EQA is essential for challenging test system accuracy, and is carried out less frequently than IQC testing. EQA samples are tested ‘blind’ and the results are returned to the scheme organiser. As EQA testing compares an individual lab’s performance to other labs using the same method and instrument, it is a very effective tool for identification of potential issues.
Is there any disadvantage to using IQC and EQA material from the same provider?
The answer to this question depends primarily on the source material of the IQC and EQA. If an IQC provider manufactures their material using artificial additives or components of animal origin, then it will not be suitable to use EQA material from the same provider. Westgard (2011) maintains that using non-commutable IQC or EQA material can lead to results becoming compromised due to matrix effects – something which would not happen using commutable controls.
For example, with Immunoassay testing, non-human components of IQC material interact with antibodies in the reagent in a different way to fully human patient samples – ultimately giving unpredictable shifts, and not adhering to the ISO 15189 requirement to: “use quality control materials that react to the examining system in a manner as close as possible to patient samples”.
However, if the IQC and EQA material is manufactured using a source material which is similar in composition to patient samples (100% human), this commutable control will adequately mimic patient sample performance; meaning labs can use EQA and IQC material from the same provider with confidence that the integrity of their results is maintained.
ISO 15189 also states: “Use of independent third party control materials should be considered…”. In this instance, ‘Independent’ does not mean from a separate provider. It means that the QC material should not be optimized for use on one specific instrument (i.e. not dependent on a single instrument/method type).
No regulatory body states a requirement to use different providers for IQC and EQA material. Indeed, using IQC from one provider and EQA from another provider could increase the risk of labs using non-commutable material.
Labs should use commutable IQC and EQA material for a true assessment of their test system. Randox QC and RIQAS EQA are specifically designed with commutability in mind, giving labs a control which reflects patient sample performance and ensures excellent performance.
How can we help?
To learn how Randox can offer a complete solution for your laboratory, follow the links below or submit a question using the form above.
Westgard, S. (2011). Is QC Quality Compromised?. Available: https://www.westgard.com/qc-quality-compromised.htm. Last accessed 31st October 2017.
Got a question?
In a QC survey conducted this year, Sten Westgard reached out to more than 45,000 laboratory professionals to gain a comprehensive view of the world’s Quality Control practices. It was one of the largest surveys that have been conducted and shared publicly.
Read on as we take a summarised look at our favourite bits.
Setting control Limits
Most labs are using their actual performance to set their mean and SD, however, a large percentage of labs still use manufacturer’s ranges, peer group ranges, and other non-individual sources for SD. These ranges can typically be set wider than they would if the ranges were based on their actual mean and SD. This can result in labs releasing incorrect patient results.
Laboratories were asked if they used 2 SD control limits on all tests and it was found that a majority use 2 SD. The strict use of 2 SD can generate a high level of false rejections (9% for two controls and higher for three). This causes a high level of out-of-control events; the use of QC multi-rules is recommended.
The types of Controls used by labs
More than 60% of labs were found to be using manufacturer controls, the drawbacks of which are well known. The latest ISO standards strongly encourage the use of independent / third-party controls. Westgard speculates that this will become a mandatory requirement in the next version of ISO 15189.
Frequency of QC
The first question about frequency asked how often labs ran QC during a run. Respondents reported how often they schedule QC in their labs. Around half only run QC at the beginning of a run with labs running it throughout the day coming in close second. A small proportion of labs reported running QC at both the beginning and the end of a run.
The final, least popular option involves spacing out QC based on test volume, the most scientific method determining how many patient samples can be run between controls without raising the risk of unacceptable results.
The next question asked about the overall frequency of QC. Most labs are meeting the once-a-day minimum standard for CLIA regulations.
“QC frequency remains primarily based on the rotational speed of the earth, not driven by needs of the clinician and patient.” – Sten Westgard
QC Frequency Influences
Regulator and accreditation requirements lead the way in influencing the frequency of QC with manufacturer recommendations, and professional judgement following close behind. Only a quarter of labs use the volume of testing to guide their QC frequency and one in six look to EP23 or IQCP for guidance.
Most labs are using on-board instrument informatics to support their QC charting, followed by LIS charting programs, and peer group software.
Of significance is the number of labs using Excel spreadsheets as their primary QC tool as well as standalone QC programs or even manual graph paper. This could be due to varying technological capabilities where some locations may not have access to, or the funds to afford, informatics.
A combined third of labs are out-of-control every day. In some labs this could be the result of running such a high volume of controls that false rejections are inevitable. However, rationalising in this way can lead to ‘alert fatigue’, where users begin to ignore alert flags and stop troubleshooting.
More than a quarter of labs have an out-of-control flag every few days while another roughly one in six have just one per week. A small number of labs report having few QC flags.
Managing QC Costs
Finally, laboratories were asked about the steps they take to manage QC costs. 60% claimed that they take no steps to manage costs. One in six reduced QC frequency, one in eight switched to cheaper controls, while, worryingly, almost one in ten changed their QC rules or widened limits.
Westgard’s Global QC Survey suggests there exists many inefficient implementations of Quality Control, with plenty of room for improvement. The current state of QC is, like many aspects of healthcare, unsustainable. Labs must adopt better approaches or risk their continuing feasibility, or worse, their patient’s results.
How Randox Can Help
Westgard highlights particular issues with labs mismanaging costs, still using manufacturer controls, and setting control limits – this is where Randox comes in.
Acusera Third Party Controls offer the highest quality solution for any lab – regardless of size or budget. Designed to provide an unbiased, independent assessment of performance, our internal quality controls have not been manufactured in line with, or optimised for use with any particular reagent, method or instrument helping you to easily meet ISO 15189 recommendations. Unrivaled consolidation allows for significant cost savings.
Acusera 24•7 Live Online allows you to automatically apply multi-rules and generate charts to help with setting accurate control limits, helping you get your quality control under control.
Reference: Westgard, S (2017), The 2017 Great Global QC Survey Results
World Diabetes Day
With World Diabetes Day on Tuesday 14th November 2017, we take a look at what diabetes is and why quality control is so important.
What is Diabetes?
Diabetes is a life-long condition which occurs when the glucose level in the blood is too high because it can’t enter the body’s cells to be used as fuel. There are two types of diabetes: type 1 and type 2. They are distinct conditions and must be treated and managed differently.
Type 1 Diabetes
Type one diabetes is an autoimmune condition in which the body attacks insulin-producing cells, this causes a lack of insulin, leading to an increased blood glucose level. Around 10% of people with diabetes has type 1.
Type 2 Diabetes
A mixture of genetic and environmental factors causes type 2 diabetes. The body doesn’t make enough insulin or the insulin it does create does not work correctly, leading to a glucose build up in the blood. It’s thought that up to 58% of type 2 diabetes can be prevented or delayed through healthy lifestyle choices.
Role of Quality Control
Quality control plays a crucial role in ensuring accurate and reliable diabetes monitoring. 70% of medical decisions are based on a laboratory test result and QC is vital in ensuring the results the laboratory report are both accurate and reliable.
Want to know what makes a good HbA1c control? Read on to find out.
Clinically Relevant Levels
In the diagnosis of diabetes, glycated haemoglobin (HbA1c) in blood provides an indication of average blood glucose levels in the previous three months. HbA1c is the recommended standard of care for type 2 diabetes monitoring. HbA1c is measured using the range below:
HbA1c – Clinically Relevant Levels
|Normal||Below 42 mmol/mol||Below 6.0%|
|Prediabetes||42 to 47 mmol/mol||6.0% to 6.4%|
|Diabetes||48 mmol/mol or over||6.5% or over|
It is important to assess the full clinical range of an assay, i.e. the range between the lowest and highest results which can be reliably reported. 48 mmol/mol is the cut-off for diabetes diagnosis, it is crucial that this can be measured accurately because any inaccuracy could mean the difference between being diagnosed and treated and not.
In terms of accreditation, ISO 15189:2012 states, ‘The laboratory should choose concentrations of control materials wherever possible, especially at or near clinical decision values, which ensure the validity of decisions made’.
Benefits of Third Party Controls
The importance of third party controls is evident. Third party controls can help identify instrument, reagent, and procedural errors. Unchecked these errors could lead to incorrect patient results, further leading to misdiagnosis.
Third party quality control material has not been designed or optimised for use with any instrument, kit, or method. This complete independence enables the quality control material to closely mirror the performance of patient samples, and in doing so, provide an unbiased, independent assessment of analytical performance across multiple platforms.
Again, in terms of accreditation, ISO 15189 states – “use of independent third party control material should be considered, either instead of, or in addition to, any control materials supplied by the reagent or instrument manufacturer.”
Many laboratories perform HbA1c testing on a dedicated machine and as a result, are not always using a third party control.
Wastage is a common issue when running HbA1c due to the pre-treatment step required for many HbA1c controls and poor stability of some controls on the market. Look out for controls with an extended open vial stability to help reduce waste and keep costs low.
How can Randox help?
To help you get your QC in check for World Diabetes Day, Randox Acusera HbA1c control contains both HbA1c and Total Haemoglobin, with a reconstituted stability of 4 weeks to reduce waste and reduce costs. To find out more about our HbA1c control visit the page using the button below or fill out the form above.
An important consideration when choosing your Quality Control material that is often overlooked is the shelf life of the control. With every new lot of control extensive validation studies must be performed. Regulatory bodies such as CLIA require new lot numbers to be evaluated before routine use in the laboratory. For example, CLIA has instructed that any new control lot to be run alongside patient samples will need to be verified alongside the old lot of control. The process is designed to give laboratory professionals confidence in the new material and ensure it is fit for purpose before implementing it in the lab.
As part of the validation process laboratories are required to assay both the old and new lots side by side. The current lot is then used to help verify if the new lot will be acceptable to run within the lab. Such validation studies can be very costly for a lab as well as being extremely time consuming – with some studies taking up to a month to complete! By choosing a control with a longer shelf life laboratories can aim to use the same lot of control for a longer time period. Ultimately this means fewer lot changes and minimal inconvenience for the lab. With a shelf life of 2 years for liquid controls and up to 4 years for lyophilised, coupled with unrivalled stability claims, employing Randox Quality Control in your laboratory will ensure that expensive lot changes will be a thing of the past. Our comprehensive control offering is guaranteed to increase efficiency and reduce costs in any laboratory without compromising on quality.
Contact us today to find out more information on our Acusera range of Quality Controls.