Holo‑TC; sensitive B12 marker.
How would you like to take the test?
The analyses are the same. Choose between collecting your sample at home or having blood drawn at a collection point.
Blood collection at collection point
After your order you receive instructions by email
Make an appointment at a collection point near you
Blood collection at 1,000+ locations across the Netherlands
Holotranscobalamin (HOLO-TC) is a biomarker that measures the amount of vitamin B12 in the body that is directly available for cellular uptake. It is an early indicator of vitamin B12 deficiency, as it only reflects the portion of vitamin B12 that can be actively used by the body.
Testing HOLO-TC is useful for people experiencing symptoms that may indicate a vitamin B12 deficiency, such as fatigue, weakness, memory problems, or neurological changes. It is also valuable for individuals at risk of vitamin B12 deficiency, such as the elderly, vegans, and people with certain stomach conditions or who use specific medications.
HOLO-TC levels indicate the amount of immediately available vitamin B12 in the blood. This helps determine whether the body has sufficient vitamin B12 for essential functions such as DNA synthesis, blood cell production, and nerve maintenance.
A high level of HOLO-TC is generally uncommon and is less frequently associated with health problems. However, in rare cases, it can indicate certain medical conditions or the use of vitamin B12 supplements.
A low level of HOLO-TC indicates a deficiency of available vitamin B12 in the body. This can lead to various health problems, including anemia, nerve damage, fatigue, and cognitive impairments.
This test is included in Dutch healthcare guidelines and is regularly used for its respective indications.
Rationale for this test
Holotranscobalamine (holo-TC) is een gevalideerde biomarker voor vitamine B12-status die in de Nederlandse reguliere zorg wordt gebruikt. De test meet het direct beschikbare vitamine B12 en is een vroege indicator van tekort. De klinische betekenis is goed onderbouwd in zowel Nederlandse als internationale richtlijnen voor diagnostiek van vitamine B12-deficiëntie.
Dutch clinical guidelines and healthcare organisations
International scientific literature
We recommend consulting these independent sources before ordering a preventive health check.
Brochure on preventive health checks: careful choice, reliability, pros and cons, checklist.
Independent information about preventive health checks from the National Institute for Public Health and the Environment.
Reliable patient information about illnesses and complaints from Dutch GPs (NHG).
Public-facing website of the Dutch Society for Clinical Chemistry with explanations of blood tests and laboratory values.
Practical information
After ordering we generate a referral letter and email you the instructions. You pick a collection point yourself and book an appointment there. Blood is drawn at the location, processed at the lab, and your result arrives digitally.
Often within a few working days. How soon you can be seen depends on how busy the location is and the type of analysis. For specialist analyses we first ship collection materials, which takes a bit longer.
At most collection points yes. Some accept walk-ins. This is clearly indicated per location. You choose the location that works best for you.
That depends on the test. Whether fasting is required, and from what time, is clearly stated in the instructions you receive after ordering. No surprises at the counter.
It varies per analysis: from same-day to a few working days. Standard values often come back quickly; analyses that go to an external lab can take a bit longer. You receive your laboratory report securely by email. It lists the measured values, units, reference ranges and any flags added by the laboratory.
We work with 1,000+ collection points across the Netherlands. After ordering you'll see which locations near you are available and you pick where you'd like to go.
“Very positive experience”
From ordering to having my blood drawn, everything went smoothly and was well organised. I really appreciated being able to visit a blood collection location in my own town so quickly. I received clear instructions beforehand, and the results arrived promptly by email too. Very satisfied!
“Good communication”
This company responds to questions thoroughly and promptly. The entire process, from requesting the test to having blood drawn and receiving the results, runs very smoothly. Overall, I am very satisfied!
“Wide choice of tests, fast and affordable”
You can choose the tests yourself. Fast delivery and processing, clear instructions and affordable.
“I am satisfied with the service”
I received a referral by email, just like from a GP. I did not have to send anything by post and could quickly visit a local blood collection centre. The results were fast and clear. The price was good, not too expensive, and all messages were secure.
“A very good experience”
A very good experience! I received quick answers to my questions, a custom blood test was put together, everything was arranged smoothly, and I could have my blood drawn by a healthcare professional nearby. The results were available within a few days. In short, very satisfied!
“Very good customer service”
The customer service is very good. I had a complex request, which caused an issue at the blood collection centre. Customer service resolved it very well. They also offer a wide range of tests at a reasonable price.
“Everything was well organised”
Everything was well organised. The products were delivered within a few days and, after sending in the samples, the results arrived within a few days too. Communication and information throughout the process were clear and friendly.
“Fantastic service”
Fantastic service! Very good customer service that responds quickly and thinks along with you. Good prices. I will definitely use BloedCheckup's services again.
“Very happy to have found this business”
Very happy to have found this business. We need to check our blood more often :) The process was easy. They sent me the kit at home, then I had to go to a clinic with the papers and they knew what they had to do. I got the results in less than a week.
“Smooth process and good support”
Amazing website experience. I ordered various tests for 2 people. We went to one of the supported centers and took samples. Also after the results were ready, I needed a letter from the laboratory and they prepared the letter for me in no time. Definitely recommended.
“Amazing service!”
Received a packet with everything needed, went to a walk in clinic (Amsterdam DC Clinic) where my blood was drawn and I was out the door within 5 minutes, and then after posting the samples, received results 2 days later. Results were easy to understand as well. Amazing service, would highly recommend!
“Great customer service”
I ordered a test through bloedcheckup.nl but later realized I no longer needed it. I contacted their support team, and they were very quick, responsive, and helpful in handling my cancellation. The whole process was smooth and efficient. Great customer service!