In medicine, some blood tests are conducted on venous blood obtained by fingerstick or fingerprick. After a droplet has formed, venous blood is sucked up in a capillary tube, usually relying on surface tension, but sometimes using indirect suction.
Tests commonly conducted on capillary blood 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 check if a blood or plasma donor has a high enough blood count to be allowed to donate blood or blood components.
- Genetic testing – heelprick testing of a newborn's DNA allows for early diagnosis and mitigation of common hereditary disorders.
- Full CBC (complete blood count)
- Prothrombin time
Fingersticks are sometimes performed on children and the elderly, when only a small amount of blood (less than 500 μg) is needed for a test. Neonates (newborn babies) are given heelpricks instead, as this is less likely to cause permanent damage.
- Heelpricks, section "Blood collection on babies"