The Blood Spot Reference Guide explains how the laboratory evaluates dried blood spot cards, including the number and quality of sample punches needed for different panels. It is a reference document, not a complete finger-prick procedure, so follow the collection steps supplied with your specific kit.
What does “punch” mean?
A blood spot punch is a 6 mm circle cut from the dried sample card by the laboratory. The guide estimates that each punch holds about 12.5 microlitres of blood, and says zero to three punches may be taken from a spot depending on its diameter. The number listed for your panel is the laboratory’s requirement, not a number of holes for you to cut into the card.
Punch requirements vary by test code. For example, the guide lists one punch for B-208 HbA1c, two for B-203 TSH, six for B-222 CardioMetabolic, and five for B-240 to B-243 hormone panels. Check the complete table in the PDF against the panel code on your requisition.
What makes a good blood spot?
The guide describes good spots as uniform in shape, size and saturation. It flags spots that are too small, poorly saturated, irregular or smeared, as well as double spotting and contamination from an alcohol pad that has not dried. Small spots may be rejected, and sample quality can affect whether enough material is available for testing or confirmation.
Help prevent contamination
- Lay out and prepare the collection materials before you begin.
- Write your name, date and collection time on the card before washing your hands.
- Wash your hands with soap and warm water, then dry them with a clean towel. Avoid touching surfaces that may have hormone or element residue afterward.
- Do not touch the filter paper except to apply blood drops. Clean the finger with the alcohol pad and let it air-dry before collecting.
- Wipe away the first drop with the supplied gauze, and avoid letting blood run over or under the fingernail.
If you cannot ship the sample within 24 hours, the guide says to place the card in a clean, unused zip-top bag and store it in a safe area of the freezer. Follow any additional storage or return instructions provided with your kit.
Browse dried blood spot tests
Explore the Dried Blood Spot Tests collection, including the HbA1c test (panel B-208) and the TSH test (panel B-203). Always check the code and sample steps for the test you have selected.
This guide covers sample quality and handling only. It is not medical advice or an interpretation of results. Follow the instructions supplied with your kit and contact the laboratory or a qualified healthcare professional if you are unsure about collection.