Customer stories: Erasmus MC

Erasmus MC is investigating whether patients can collect blood at home and send it to the laboratory by post. Clinical chemist Dr Christian Ramakers is helping determine which biomarkers in the blood can still be measured reliably after that journey. During the pilot, Tapp’s temperature loggers reveal exactly what samples experience along the way.

Bringing blood collection closer to home

Between 5,000 and 6,000 tubes of blood arrive at the Erasmus MC laboratory every day. As a clinical chemist, Christian Ramakers is ultimately responsible for the quality of the laboratory and the results it produces. Alongside that daily operation, he works with doctors and researchers on innovations that could improve patient care.

One of those innovations is blood collection at home. In an ongoing study with the surgical oncology department, patients who have previously been treated for colorectal cancer collect a small blood sample themselves. The sample is used to measure a tumour marker that can indicate whether the cancer may have returned.

“These patients have often undergone surgery and chemotherapy and may have negative associations with the hospital,” Christian explains. “Monitoring them from home can therefore make a real difference.”

Using a device placed on the upper arm, patients can collect capillary blood without visiting a blood collection centre. The tube is then packaged and sent to Erasmus MC through the regular postal service.

When a letterbox reaches 40°C

But before this approach can become part of regular care, one essential question needs to be answered: is the blood still suitable for analysis when it reaches the laboratory? A sample may spend 24 to 48 hours travelling through letterboxes, vehicles and sorting centres. On a warm day, Christian measured temperatures of up to 40°C inside a letterbox.

Heat and time can have a serious impact on the integrity of the blood sample. Red blood cells may begin to break down, causing substances from inside the cells to leak into the surrounding plasma. This can distort laboratory results. “Potassium can rise from around four to seven because it leaks out of the blood cells,” Christian explains. “Glucose can move in the opposite direction because the cells continue to consume it.”

The result may be falsely elevated or falsely low. That could lead a doctor to believe something is wrong when it is not or conclude that everything is fine when further investigation is needed. “Doctors rely heavily on laboratory results,” Christian says. “That gives us a responsibility to measure with the highest possible precision and quality.”

Putting blood samples in the post

To find out which tests remain stable after transport, Christian designed a practical experiment using residual blood samples from the laboratory. He divides the material between two tubes. The first is analysed immediately to establish a baseline. The second is packaged with a Tapp temperature logger and placed in an actual letterbox. 

After travelling through the regular PostNL network, it returns to Erasmus MC one or two days later. Christian then repeats the analyses and compares the results. Meanwhile, the Tapp logger records how the temperature changed throughout the journey. “That temperature history is essential,” he says. “It allows me to see within which temperature range a particular biomarker can still be measured reliably.”

The results show why those distinctions matter. Some values, including the already mentioned potassium and glucose, change considerably during transport. Others appear surprisingly stable. Tests like creatinine, a biomarker for kidney function, CA-125, a tumour marker associated with ovarian cancer, and PSA, used in relation to prostate cancer, have so far shown promising results.

“The purpose of the research is therefore not to declare every blood test suitable for home collection. It is to determine precisely which tests can be performed reliably, under which transport conditions.”

Establishing the limits

Tapp’s role in the pilot is to provide detailed data during this research phase. “The fact that I can activate and reuse them makes them very practical for this kind of research,” says Christian. “I have been using some of the loggers for months.”

Once the safe temperature limits have been established, such detailed monitoring may not be necessary for every future sample. A simpler temperature indicator could eventually warn the laboratory when a package has exceeded its temperature window. “But first, we need to know exactly where those limits are,” Christian explains. “That is what I need the temperature data for.”

More care from home

The initial study with surgical oncology is nearing completion, while Christian continues to investigate other possible applications. These include tests related to kidney function, prostate cancer, liver cander and ovarian cancer.

If more blood tests prove suitable for home collection, patients could avoid repeated journeys to the hospital and collect their sample at a time that suits them. For Christian, that development is part of a broader shift towards greater patient involvement.

“We are slowly moving towards a situation in which patients have more control over their own health,” he says. “Home monitoring will become increasingly important, but it needs to be properly researched and regulated.”

Suitable tests will therefore be introduced gradually, in collaboration with the doctors who treat these patients. Interest in the research already extends beyond the Netherlands, with medical professionals from other countries requesting Christian’s findings.

A scientific side quest

Christian describes the project as a ‘side quest’ alongside his daily responsibilities at the laboratory. But it reflects exactly why he chose to work at an academic hospital. “I am a scientist by background,” he says. “I enjoy discovering new things and working with doctors, surgeons and oncologists who want to innovate too.”

What began with blood samples, a letterbox and a temperature logger could ultimately help make more care possible at home. But only if the laboratory can continue to trust the result.