In medicine, some blood tests are conducted on capillary blood obtained by fingerstick (or fingerprick) (or, for neonates, by an analogous heelprick). The site, free of surface arterial flow, where the blood is to be collected is sterilized with a topical germicide, and the skin pierced with a sterile lancet. After a droplet has formed, capillary blood is captured in a capillary tube (usually relying on surface tension). Blood cells drawn from fingersticks have a tendency to undergo hemolysis, especially if the finger is "milked" to obtain more blood.
Tests commonly conducted on the capillary blood collected are:
- Glucose levels – Diabetics often have a portable blood meter to check on their blood sugar.
- Mononucleosis – Fingerstick testing can be used to test for mononucleosis.
- Hemoglobin levels – Fingerstick testing of hemoglobin is a quick screening procedure to ensure a blood or plasma donor has an acceptably high blood count for donating blood or blood components.
- Genetic testing – Heelprick testing of a newborn's DNA allows for early diagnosis and mitigation of common hereditary disorders.
- Prothrombin time
Fingersticks are routine for hardy adults, but are generally performed on children and the elderly only if a small amount of blood suffices for needed tests. Neonates are given heelpricks instead, as this is less likely to cause permanent damage.
- Centers for Disease Control, Capillary blood sampling protocol (PDF)
- Carreyrou, John (21 May 2018). "A New Look Inside Theranos' Dysfunctional Corporate Culture". Wired. Retrieved 23 May 2018.
- Ansell, J.; Holden, A.; Knapic, N. (November 1989). "Patient Self-Management of Oral Anticoagulation Guided by Capillary (Fingerstick) Whole Blood Prothrombin Time". Arch Intern Med. 149 (11): 2509–11. doi:10.1001/archinte.1989.00390110085018. PMID 2818110.
- Heelpricks, section "Blood collection on babies"