Investigation of the relationship between phenylalanine in venous plasma and capillary blood using volumetric blood collection devices
Carling et al.
The finding, in our words
Volumetric capillary blood collection devices showed a -13% bias against plasma phenylalanine but produced interchangeable results after correcting for 89.4% analyte recovery, unlike conventional screening cards which performed poorly. Patients found the devices acceptable, suggesting they could support accurate home-based therapeutic monitoring in phenylketonuria.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
A 2025 review maps 28 microsampling devices, from dried spots and volumetric absorptive tips to upper-arm liquid capillary collectors, and names what a laboratory must control before their results are used: the haematocrit effect in non-volumetric dried samples, interstitial fluid from finger milking, volume, haemolysis and transport stability. Regulators on both sides of the Atlantic ask for the same two things, a device the patient can use safely and a sample fit for the test.
An IQ Consortium position paper from sponsor scientists positioning patient-centric sampling as the enabling technology for decentralised trials, and stating that a bridging study against conventional sampling “has quickly been established as a regulatory expectation”.
Maass et al., Clinical and Translational Science · source ↗
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.
Levens et al., Clinical Pharmacokinetics (paywalled) · source ↗
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.
Huhn & Scherf-Clavel, Therapeutic drug monitoring (paywalled) · source ↗
Volumetric microsampling can enable patient-centred therapeutic drug monitoring with high patient preference and acceptable method validation for many drugs, but conversion from capillary to plasma and agreement with venous sampling varies by analyte and requires careful validation.
Tummala et al., Journal of clinical pharmacology (paywalled) · source ↗