2024 · Journal of the Endocrine Society · open access
Determination of Capillary Blood TSH and Free Thyroxine Levels Using Digital Immunoassay
Suzuki et al.
The finding, in our words
Capillary sampling gave TSH and FT4 results that closely matched venous values, with Spearman correlations of 0.99 and 0.97 respectively. This supports using small capillary samples for remote thyroid function testing.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
In 46 women under hormone monitoring at Columbia University Fertility Center, oestradiol, LH, FSH, progesterone and hCG measured on routine immunoassays from 400 to 600 microlitres of upper-arm capillary blood collected with TAP Micro Select agreed closely with paired venous results for every analyte, with correlation and concordance high throughout. It is the evidence that puts a self-collected sample inside the daily monitoring of an IVF cycle.
The TAP device showed near perfect agreement with venous sampling for anti-Müllerian hormone measurements, with higher accuracy and lower pain compared to ADx card. This validates TAP as a reliable option for patient-led fertility hormone testing at home.
In 480 adults, capillary specimens from fingertip lancets or the TAP Micro Select device gave clinically comparable results to venous samples for 16 of 18 routine chemistry analytes; potassium and chloride were not interchangeable, and fingertip collection showed more haemolysis, both points to weigh before decentralised microsampling of routine chemistry.
Capillary fingerstick sampling showed high correlation and agreement with venous sampling for serum AMH but with proportional bias, so it may improve access to testing yet should not be considered fully interchangeable without further validation.
Home DBS sampling gave testosterone results that agreed well with venous blood in men on intramuscular testosterone undecanoate, but showed falsely high values in those using topical gel, likely from skin contamination. Patients preferred home collection for its convenience, suggesting DBS is viable for decentralised monitoring of injectable testosterone if patients are taught proper technique.