2019 · American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons · paywalled
Assessment of tacrolimus intrapatient variability in stable adherent transplant recipients: Establishing baseline values
Leino et al.
The finding, in our words
In highly adherent transplant recipients who collected dried blood spots at home, tacrolimus showed modest intrapatient variability with a median coefficient of variation of 15.2 per cent. This provides a baseline to help distinguish pharmacokinetic variation from non-adherence in decentralised therapeutic drug monitoring.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
This study validated a dried blood spot method for tacrolimus monitoring and demonstrated agreement with venous whole blood measurements in kidney transplant recipients. It also found that dried blood spot analysis of the biomarker CXCL-10 was elevated in patients experiencing rejection or infection, supporting its use for decentralised monitoring.
The study found that quantitative dried blood spot sampling provided high clinical agreement for tacrolimus and creatinine monitoring, with patients rating the self-collection devices as user-friendly. These results support the feasibility of decentralised therapeutic drug monitoring for immunosuppressants.
De Baets et al., Clinical chemistry and laboratory medicine (paywalled) · source ↗
A systematic review found mixed economic evidence for microsampling in therapeutic drug monitoring; one study reported no cost reduction with DBS home-sampling, €688 versus €676, whilst another predicted savings up to 61%. The authors caution that more work is required to assess costs alongside clinical outcomes and optimise logistics for decentralised implementation.
Carland et al., British Journal of Clinical Pharmacology (paywalled) · 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.
The authors observe that self-sampling devices for capillary blood are gaining traction as a patient-preferred alternative to venous collection, with one centre reporting a 15 percent reduction in laboratory test volumes when local collection was offered. They argue that successful integration into total laboratory automation requires addressing cost, transport regulations and sample volume adequacy while ensuring robust device design and seamless workflow compatibility.
Poland & Cobbaert, Clinical chemistry and laboratory medicine (paywalled) · source ↗