The revision of the Rili-BÄK also includes the requirements of Table B1.1. In an interview with MedLabPortal, Prof. Matthias Nauck explains why the upcoming changes will ultimately benefit patients and why there is still a need for discussion. Nauck is Director of the Institute for Clinical Chemistry and Laboratory Medicine at Greifswald University Medical Center and Past President of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL).

MedLabPortal: Prof. Nauck, do you know the movie e-m@il for you?

Nauck: YES! I’ve already watched it several times and always enjoy it.

MedLabPortal: We asked because the movie with Tom Hanks and Meg Ryan has a happy ending after many trials and tribulations. Like other specialist societies, the DGKL received an email from the President of the German Medical Association, Klaus Reinhardt, at the beginning of July. It was about the “decision to extend the existing transitional period for the requirements of Table B1.1 by two years”. Is this the happy ending to the discussion about pre-analytics in the Rili-BÄK with regard to plasma or serum?

Nauck: In 2019, the Presidium of the BÄK asked me to give greater consideration to the topic of preanalytics in a future revision of the Rili-BÄK, as this has a significant influence on the quality of the measurement results. The discussion about suitable sample material began around 50 years ago, and plasma has been recommended for many decades for measuring glucose and potassium. However, this knowledge has often not been implemented because it can – in some cases – make the processes more complex. These aspects of preanalytics have not been scrutinized separately in recent years, not even in the context of accreditation. The “happy ending” is perhaps the fact that – after discussions over the past two years – the extension of the transition period has now given us the same amount of time to concentrate on implementing these requirements, particularly in the private practice sector.

MedLabPortal: Please briefly explain to our readers: What is so important about Table B1.1?

Nauck: It is generally accepted that in the analytical process – consisting of pre-analysis, analysis and post-analysis – around 2/3 of all errors occur in the pre-analysis. Table B1.1 now provides clear pre-analytical specifications for glucose, which is by far the most frequently determined measurand. Here it is important to know that in blood collection tubes without glycolysis inhibition, the glucose concentration in the blood collection tubes drops by approx. 5 to 10% per hour. This means that a blood sample that does not contain glycolysis inhibitors and is only processed and measured after 3 to 4 hours has glucose values that are approx. 30% below the actual value at the time of blood collection. This means that diagnostics and therapy monitoring are simply not possible.

Alternatively, the blood sample can be measured quickly, as is the case, for example, in blood gas analysis or as part of immediate patient diagnostics for glucose measurements. Alternatively, the plasma can be obtained by rapid centrifugation and the use of gel tubes. The plasma is thus separated from the cellular components of the blood by centrifugation and the breakdown of glucose by the blood cells is stopped.

The second parameter listed in Table B1.1 is potassium. According to the KBV, around 40 million potassium determinations are currently carried out annually in private practice alone. The intracellular potassium concentration is often higher than the extracellular potassium concentration. Potassium is therefore the classic example of an interfering factor, as potassium is released from the thrombocytes in considerable quantities during the coagulation process and the potassium concentration in serum is therefore falsely high. This effect can be easily avoided if heparinate plasma is used instead of serum, because here the coagulation process – and thus the release of intracellular potassium from the platelets – is prevented.
The specifications for both measurement parameters are based on studies that in principle were carried out decades ago. And they comply with the applicable regulatory requirements, regardless of the wording in Table B1.1.
The Medical Devices Operator Ordinance states in §10: “Anyone who carries out laboratory medical examinations must establish a quality assurance system in accordance with the state of medical science and technology to maintain the necessary quality, safety and performance in the use of in vitro diagnostics and to ensure the reliability of the results obtained before commencing this activity.” Plasma, or whole blood, is the state of the art for both of the above-mentioned parameters.

The objective of the Rili-BÄK states: “The aim of this guideline is to ensure and continuously improve the quality of laboratory medical examinations and to keep risks for patients and users as low as possible. In particular, it is intended to ensure:
– the minimization of influencing variables and interfering factors in pre-analysis,
– the professional performance of laboratory medical examinations, including the detection and minimization of influencing variables and interfering factors on the examinations …”
The aim is therefore not to deal creatively with confounding variables, but to minimize them. We have met this objective by formulating the pre-analytical specifications in Table B1.1.

MedLabPortal: And you have therefore agreed on this table as a professional association with the BÄK?

Nauck: The guideline of the German Medical Association on quality assurance of laboratory medical examinations has a statutory character because it is referred to in Section 10 of the aforementioned Medical Devices Operator Ordinance. “Proper quality assurance in accordance with sentence 1 is presumed if the guideline of the German Medical Association on quality assurance of laboratory medical examinations in the version dated May 30, 2023 (Deutsches Ärzteblatt dated May 30, 2023, DOI: 10.3238/arztebl.2023.rili_baek_QS_Labor) is observed.”

At the BÄK, Department 3 is responsible for processing the Rili-BÄK. There are currently five specialist groups D1 to D5, which are responsible for the corresponding B parts of the Rili-BÄK. These specialist groups draw up proposals that are then passed on to the next higher committee for discussion. This committee is the Advisory Board for Quality Assurance of Laboratory Medicine Tests. From my predecessor in my position at the BÄK, Prof. Wolfgang Vogt, I learned and continued two core elements of committee work for the BÄK:

1. Decisions are made by consensus, i.e. unanimously.
2. The Rili-BÄK has an educational character.

The proposals are compiled from the individual specialist groups, discussed in the Advisory Board and voted on by consensus. Proposed amendments are then forwarded to the Executive Board of the German Medical Association, which decides whether to accept or reject them.

Back to your question: There are very different members on the expert committees and the advisory board, including the specialist societies you mentioned. In addition, the BÄK itself, the KBV, DKG, dvta, VDGH, representatives of the federal states, PTB and, in some specialist groups, the RKI are also represented on the committees. Professional associations are not represented. As already mentioned, decisions are made by consensus in these bodies. It is therefore by no means the case that unilateral decisions can be made here. In the translation of the Rili-BÄK into English, which appeared in the journal JLM 2024, you will find 64 authors, which clearly shows that this is a collaborative work! And to repeat: the BÄK Executive Committee decides on the proposals from the committee work.

MedLabPortal: But now there are voices calling for centrifugation to be included in the table. What is this all about?

Nauck: In addition to the Medical Devices Operator Ordinance and the Rili-BÄK, the package inserts in accordance with the IVDR are of great importance and must be taken into account when using these in-vitro products. In the discussion about the appropriateness of using serum for potassium determination, a paper by Reuter et al. was published in PLOS One in 2025, which examines the time course if the samples are not centrifuged within 30 minutes but only after 4, 6 or 8 hours. This study ignores the content of the corresponding package insert, which states: “If the sample cannot be analyzed within 2 hours, it must be separated from the cells (Roche package insert).” Conclusions derived from these test results, which were not obtained lege artis, therefore have no relevance and are not medically tenable. I am delighted that we have just been able to publish a correction in CCLM – a recognized international journal for laboratory medicine. Members of the DGKL, some of whom are active on the committees of the BÄK, and the speaker of the Extraanalytical Quality Section of the DGKL, Dr. Alexander von Meyer, have reprocessed and reinterpreted the data (CCLM 2025 Petersmann et al). Against this background, a discussion was also held on this in the D1 specialist group. However, it has not been concluded. In terms of content, however, the package inserts must be taken into account, regardless of what is stated in the Rili-BÄK. If President Reinhardt’s letter states that the debate on the table has not yet been concluded, then the issue of centrifugation should presumably be included here.

MedLabPortal: The Board of the BÄK has in turn extended the transitional period for compliance with the requirements of the table until May 2028. That’s three years from now. Without wanting to tease: China took four years to build Beijing Daxing International Airport, which is after all the largest airport in the world. Why is it taking almost as long to implement Table B1.1?

Nauck: That’s a good question that I can’t answer easily. I have already used the airport in China and was impressed by its functionality – and the short construction time. In Germany, we have a hard time with some things when it comes to change. The truck toll, Berlin Airport and the Elbphilharmonie concert hall also took time to get off the ground. Compared to these projects, we probably have an acceptable implementation time here, which we should now also use to raise the quality of patient care to a new level, from which the patients entrusted to us, but also all those involved in the healthcare system, will benefit at the end of the day.

MedLabPortal: For laboratory physicians, the specifications in the table are probably safe territory from a professional point of view. But what about general practitioners and other specialists in private practice?

Nauck: There is certainly some catching up to do here. Laboratory physicians should take on this task together with the BÄK and other professional associations in order to achieve a broad consensus and a high level of acceptance for these necessary changes and improvements in pre-analytics. Here we should jointly utilize the potential of the Rili-BÄK as an educational instrument.

MedLabPortal: And how will patients benefit from the “new” Rili-BÄK in this area?

Nauck: ” There will be significantly fewer false test results, which lead to unnecessary personal upheaval, but also unnecessary and avoidable burdens on the healthcare system. Confidence in the quality of laboratory medical diagnostics in patient care will increase and thus correspond to the aim of the Rili-BÄK: “The aim of this guideline is to ensure and continuously improve the quality of laboratory medical examinations and to keep risks for patients and users as low as possible.”

MedLabPortal: Prof. Nauck, thank you very much for your time.

The questions were asked by Marita Vollborn and Vlad Georgescu

Editorial office: X-Press Journalistenbüro GbR

Gender note. The personal designations used in this text always refer equally to female, male and diverse persons. Double/triple references and gendered designations are avoided for the sake of better readability ected.