People with diabetes often measure their blood glucose at home using a finger-stick method to collect capillary blood samples from their fingertip. Finger-stick sampling is also becoming more common in research and clinical settings – often to enable remote specimen collection for serology studies. For remote collection, the finger-stick sampling is self-managed by people at home without the need for professional assistance.
Capillary blood is sampled by using a small lancet to prick a person's finger (or upper arm, above the knee, etc.). The blood drop is then collected via a sampling tool like a Mitra® device or the hemaPEN.
The sampled device is closed into its protective cartridge and placed in a sealed specimen bag, which fits inside a pre-stamped envelope. The envelope can be dropped in the nearest mailbox for sending to the lab. The blood sample on the device will dry in transit, and will be analyzed in the lab as a dried blood microsample.
In the lab, 4 precise DBS samples can be retrieved, processed and analyzed following a DBS workflow.
For the most part, capillary and venous blood can be used for the same serology applications without affecting the validity of the test results. There are some small differences in hemoglobin and hematocrit levels measured in each. These differences may vary in significance depending on things like a person's gender and the iron levels in their blood, for example.
Capillary blood also usually has significantly higher blood glucose levels than venous blood collected from the same person. However, tests comparing how well each type of blood performed when screening for antibodies for measles showed that both types were equally reliable for this purpose. Capillary blood samples have proven to be very useful in antibody studies of influenza and other viruses as well.
Capillary blood’s proven reliability in antibody testing means the finger-stick method for dried blood sampling can be used to conduct serology studies of viruses, such as SARS-CoV-2.
Serology studies are one of the primary ways we investigate contagious diseases, to investigate the antibodies developed in response to viral infections. Serology using microsamples can tell scientists which antibodies are produced after a person is infected with a particular virus, as well as how long those antibodies might remain over time to protect the host from reinfection.
Serology blood testing has become more important than ever as a result of the Coronavirus Pandemic. Antibody testing was used to develop the COVID-19 vaccines that are providing populations with some protection against new infections from SARS-CoV-2. Scientists also use blood tests to identify and screen for SARS-CoV-2 variants as the virus mutates and evolves. Blood tests are also being used to develop booster shots that will help defend against variants of concern, when needed.
Capillary blood testing often can be used for remote specimen collection in place of phlebotomy services and in-clinic blood draws. The remote approach to specimen collection for lab testing helps to avoid exposure risks between researchers, clinical staff, and study participants, which is crucial to limiting the spread of SARS-CoV-2 and other pathogens. Remote blood collection has recently been used for a number of high-profile COVID-19 serology studies, including the National Institutes of Health (NIH) to track undetected cases of COVID-19, and recent efforts by Stanford University to study the impact of vaccination on a person's immunity and other body systems.
There are many reasons for researchers and clinicians to consider remote capillary blood sampling to replace venipuncture blood draws.
Capillary blood collection can be done at home with simple user-friendly devices like Mitra devices. The remote, self-managed approach is far more convenient for study participants who wish to avoid frequent visits to a blood draw center, or long commutes to medical centers. Offering remote options to participants or patients makes them more likely to adhere to recommended blood testing schedules.
Like any method of sample collection, capillary sampling has its limitations. Here are some things to consider when opting for capillary sample collection:
Overall, capillary blood sampling with finger-stick microsampling methods are promising alternatives to venous blood draws. The two methods are not always interchangeable, and their strengths and weaknesses must be taken into account in each use case. However, when capillary blood is used for a suitable application, it offers a range of benefits that make it an appealing choice for all parties involved.
Learn more about capillary blood microsampling and its applications by visiting our Microsampling Applications page:
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