Finger-prick, Tasso or Venous? A Guide to Blood Test Collection and Validation

There is no single best way to collect every blood sample. Finger-prick and Tasso collection can work well for selected biomarkers validated for capillary blood and postal transport. Broader panels, unstable whole-blood markers and tests requiring centrifugation are generally better suited to venous collection.

How Vitall chooses the right blood collection method

Blood test accuracy depends on more than the analyser used in the laboratory. The biomarker, sample type, collection tube, sample volume and time before processing can all affect the result.

Vitall selects the appropriate collection method based on the specific biomarkers in each panel. Most of our tests can be combined seamlessly using a single finger-prick serum-separator tube (SST). Other tests - such as HbA1c or a full blood count - require whole blood collected in an EDTA tube, while sexual health testing utilises swabs and urine samples. We also offer stool and saliva sample collection.

Where tests need multiple sample types, Vitall optimises collection to provide the most reliable and cost-effective options to you. This may include self collection, national clinics, a home nursing visit, or for electrolytes and insulin requiring timely centrifugation, mobile nurse centrifugation services.

The short answer: the right collection method depends on what is being measured. We use finger-prick collection where the biomarkers have been validated for capillary sampling and postal transport. We recommend venous collection when a panel needs more blood, multiple sample types or faster processing.

Three ways to give a blood sample

Vitall offers three collection routes. The best option depends on the biomarkers in the panel, the sample volume and processing required, and the user’s preference. A test should only show collection methods that are valid for that panel.

Collection method	How it works	Best suited to	Important limitation
Self-collection	The user collects a capillary blood sample at home with a finger-prick lancet or an upper-arm Tasso device, then returns it by post.	Validated capillary panels, privacy, flexibility and programmes where avoiding an appointment improves access.	Not appropriate when the panel is venous-only, needs prompt centrifugation or has not been validated for postal capillary collection.
At-home nurse visit	A qualified nurse visits the user and takes a venous sample from the arm. The sample can be centrifuged where the panel requires it.	Users who are uncomfortable self-collecting; broad panels; larger volumes; multiple tubes; and tests requiring a venous or centrifuged sample.	Costs more than self-collection and requires an appointment.
In-clinic collection	A trained professional takes a venous sample at a clinic.	Broad or complex panels, venous-only biomarkers, full blood count testing.	Requires travel and a booked appointment.

Tasso self-collection vs finger-prick lancet

What is the difference between Tasso and a finger-prick lancet? Both are forms of capillary self-collection. A lancet requires the user to prick a fingertip and manually fill a small tube. A Tasso device is applied to the upper arm and automatically collects blood into its container. Tasso can make collection feel simpler; a lancet keeps the kit more affordable. Neither method changes the biomarker’s specimen or processing requirements.

Decision factor	Finger-prick lancet self-collection	Tasso self-collection
How the sample is collected	The user pricks a fingertip, encourages blood flow and adds drops to the collection tube.	The user applies the device to the upper arm, presses the button and waits while it collects the sample.
Main benefit	Lowest-cost self-collection route, with a small and familiar kit.	Less hands-on collection and no need to squeeze drops from a fingertip into a tube. Less prone to sample collection issues.
Most beneficial when	One small, validated capillary sample is required; the user is comfortable self-collecting; or price is important for a high-volume or entry-level programme.	The panel is validated for the device and ease of use matters most, particularly for nervous first-time testers, people who find finger-prick tube filling difficult or premium repeat-testing programmes.
Sample and tube fit	Low-volume SST, Serum or EDTA microtainer tubes. Validated for capillary collection by lancet (finger-prick) and postal transport.	Low-volume SST, Serum or EDTA microtainer tubes. Validated for capillary collection by Tasso and postal transport.
Common failure risks	Underfilling, clotting or haemolysis can occur if collection is slow or the finger is squeezed heavily.	Much more resilient to sample collection issues, although poor placement or low blood flow can still cause underfilling.
Cost	Usually the lower-cost option and suitable for cost-sensitive programmes.	Adds a small premium cost to each kit.
When a panel needs SST and EDTA	Filling two finger-prick tubes adds collection time and increases the opportunity for underfilling, clotting, haemolysis or sample failure.	An additional device or more complex configuration may be required, making the test materially more expensive.
Do not choose it when	The biomarker is venous-only, needs rapid centrifugation or is not stable in a postal capillary sample.	The same restrictions apply. An easier device cannot make an unsuitable biomarker suitable for home collection.
Vitall recommendation	Use when the test needs one capillary sample (this can include multiple tests) and affordability is the priority.	Offer when the expected improvement in user experience justifies the higher unit cost.

Vitall’s decision rule:

Use a lancet for a single, validated low-volume capillary sample when affordability matters.
Offer Tasso when a simpler self-collection experience (improved user experience) justifies the additional cost.
Move to venous collection for panels requiring both SST and EDTA, venous-only biomarkers, full blood count pathways where postal whole-blood stability is insufficient, or markers such as electrolytes that require prompt centrifugation.

What are SST and EDTA blood samples?

SST and EDTA tubes prepare blood in different ways. One cannot automatically replace the other.

Sample type	What it does	Common uses
SST serum sample (yellow)	Allows the blood to clot and the gel layer helps separate serum from the blood cells when centrifuged in the laboratory.	Cholesterol, liver markers, thyroid hormones, vitamins, minerals and many other chemistry tests where the marker is present in the serum..
Serum sample (red)	Allows the blood to clot, serum is separated from the blood cells in the laboratory.	Cholesterol, liver markers, thyroid hormones, vitamins, minerals and many other chemistry tests where the marker is present in the serum.
EDTA whole-blood sample (purple)	Contains an anticoagulant that prevents clotting and preserves the whole-blood sample for analysis.	HbA1c and full blood count measurements where the components of the blood e.g. cells, haemoglobin need to be assessed directly.
Centrifuged serum or plasma	Uses a centrifuge to separate serum or plasma from the blood cells within a defined period.	Electrolytes, insulin and other markers that become less reliable when left in contact with cells.

Why does a broad blood test sometimes need two samples?

A panel combining serum chemistry with HbA1c or a full blood count may require both an SST sample and an EDTA sample.

Collecting two capillary tubes at home means collecting more blood and completing more handling steps. This increases the chance of an underfilled tube, clotting, haemolysis or one sample being unsuitable for analysis. Autodraw devices such as Tasso can make self-collection easier for some people, but multi-tube configurations add device and consumable costs that can make the overall test significantly more expensive.

For panels requiring both SST and EDTA, Vitall will normally recommend venous collection unless the self-collection configuration has been specifically validated and remains sensible for sample success, customer experience and price.

Why is venous collection preferred for a full blood count?

A full blood count measures blood cells rather than substances within serum. It requires EDTA whole blood, and the sample must remain properly mixed and free from clots.

Capillary FBC testing is possible, but it is more vulnerable to clotting during collection and to changes during transport. Current laboratory guidance reports average capillary failure rates of approximately 15-20%, although better collection technique can improve this.

Vitall therefore prefers a venous EDTA sample for FBC where practical, particularly when it forms part of a larger health panel. This provides a larger, correctly filled sample and reduces the likelihood of asking the customer to repeat the test.

Why do electrolytes need venous collection and centrifugation?

Electrolytes can change when blood remains in contact with its cells after collection. Sodium, potassium, chloride, bicarbonate and phosphate, alongside insulin, may become unsuitable if the sample is not centrifuged within approximately six to eight hours.

These markers are not suitable for an ordinary finger-prick sample returned through the post. Vitall uses a clinic or appropriately equipped home-nurse pathway when a panel includes them, allowing the sample to be collected venously and processed within the required period.

Which markers may be better suited to venous collection?

Some biomarkers are particularly sensitive to haemolysis, where red blood cells are damaged during collection or transport. These include AST, LDH, creatine kinase and folate.

Their suitability for self-collection depends on the exact assay, collection device, tube and validated postal window. Vitall may restrict these markers to venous collection or use a different panel design when the risk of sample failure is too high.

Can a finger-prick blood test be as reliable as a venous test?

Yes, when the exact biomarker has been validated for capillary blood and remains stable during the expected postal journey.

Validation is assay-specific. A finger-prick route that works well for cholesterol does not prove that the same route is suitable for FBC, electrolytes or every hormone. We assess the biomarker and collection journey together rather than applying one collection method to every test.

How does Vitall assess a blood collection route?

Before confirming a collection method, the relevant evidence should establish:

Scientific review

Dr. Kate Bishop

Chief Scientific Officer - Vitall|Profile

Kate holds a BSc (Hons) in Biochemistry from the University of Birmingham and a PhD in Biochemistry. She has extensive experience in biomedical research and scientific programme management. In addition to her work with Vitall, Kate serves as Director of Operations at the College of Medical and Dental Sciences, where she supports research, innovation and academic development across biomedical disciplines.

Reviewed on 03/11/2026

Next review due 03/11/2027

Review focus: Blood biomarkers, laboratory testing methodology, and biochemical interpretation.

This content has been reviewed for biochemical accuracy and interpretation of laboratory biomarkers, but does not replace advice from a qualified healthcare professional.