Newborn screening blood spot analysis in the UK: influence of spot size, punch location and haematocrit
Lawson et al.
The finding, in our words
In newborn screening, dried blood spot size, punch location and haematocrit substantially affect measured analyte concentrations, with edge punches increasing values up to 35 percent and small spots decreasing some amino acids by 15 percent or more. These variables must be controlled to minimise false positive and negative rates in decentralised screening programmes.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
The study validated an LC-MS/MS method for eight antiepileptic drugs and two metabolites in dried blood spot and VAMS formats, with satisfactory analytical performance and stability, and was the first to include the oxcarbazepine metabolite DHCB. In 80 paired patient samples, microsampling concentrations showed promising correlation with plasma, supporting decentralised therapeutic drug monitoring of antiepileptic treatment.
Cobo-Golpe et al., Journal of analytical toxicology · source ↗
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.
A validated high-throughput LC-MS/MS assay for piperaquine from dried blood spots achieved 54-72% recovery with <9% relative standard deviation and a quantification limit of 3 ng/mL, enabling detection for 4-8 weeks post-dose. The method showed minimal haematocrit interference and is suitable for therapeutic drug monitoring of antimalarial treatment in resource-limited settings and pediatric populations.
Blessborn et al., Journal of mass spectrometry and advances in the clinical lab · source ↗
The authors developed and fully validated a liquid chromatography-mass spectrometry method to measure biotin deficiency biomarkers from dried blood spot samples. They demonstrated correlation with plasma measurements and applied the method to establish population reference ranges in South India, supporting decentralised screening and monitoring of biotin deficiency.
This narrative review evaluates microsampling devices for therapeutic drug monitoring, concluding that techniques such as volumetric absorptive microsampling and dried blood spots offer reliable, less invasive alternatives to venous sampling when paired with high-sensitivity mass spectrometry, which supports implementation in routine clinical practice.