Hematocrit-Independent Sampling Enables White Blood Cell Counts from Patterned Dried Blood Spot Cards
Tierney et al.
The finding, in our words
Patterned DBS cards meter reproducible volumes of dried blood across a range of haematocrits, allowing accurate white blood cell counts by qPCR that match HemoCue measurements. This enables reliable at-home sampling for populations without easy access to clinical facilities.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
In AML and CLL, 91% of VAMS venetoclax results fell within 20% of plasma after individualised haematocrit correction; in home sampling, 18 of 21 patients self-sampled independently and 76% of returned samples were analysable, which shows home microsampling is workable, though the authors ask for multicentre validation.
This review found that volumetric microsampling devices, such as Mitra, HemaPEN, HemaXis DB10, and Tasso-M20, overcome haematocrit bias, whilst Telimmune plasma separation cards enable direct plasma collection without centrifugation. These technologies support patient-centric, decentralised sampling, though the authors note that clinical validation remains limited across different drugs and patient populations.
Capillary dried blood spots, after haematocrit-dependent conversion, showed good agreement with plasma for 25-hydroxyvitamin D quantification, with 90 per cent of results within 20 per cent of plasma and substantial to almost perfect agreement in status classification, supporting reliable home self-collection for large-scale vitamin D monitoring.
Capillary finger-stick dried blood spots demonstrated strong analytical agreement with venous serum for prostate-specific antigen (R² = 0.987) and remained stable for 31 days across a wide temperature range. This less invasive microsampling approach enables at-home self-collection, supporting decentralised screening and tele-diagnostics for prostate cancer.
Finger-stick dried blood spots produce creatinine measurements that correlate strongly with venous plasma (R² = 0.97), with 91% sensitivity and 96% specificity for detecting reduced eGFR. Creatinine stays stable in dried spots for up to one month at refrigerated or frozen temperatures, supporting accurate home-based kidney function screening, patient follow-up, and medication management.