Comparison of capillary finger stick+venous blood sampling for 34 routine chemistry analytes: potential for hospital+remote blood sampling

[helvella]

The validity of tests using fingerprick blood samples has long been questioned. Some claiming they are unusably awful. Others claiming tests are as good as those done on venous blood.

It is good to see a paper which has researched the questions.

Unfortunately, while they did include TSH, they did not cover FT4, FT3 and several other frequently discussed analytes.

Also, they call the samples "capillary" and, while that is a proper term, it is a shame that there is the possibility of confusion with samples obtained using devices like Tasso which are sometimes expressly called capillary devices. Hopefully there will be further research covering Tasso and similar devices.

And the good news? Broadly, fingerprick tests can be pretty good!

Comparison of capillary finger stick and venous blood sampling for 34 routine chemistry analytes: potential for in the hospital and remote blood sampling

Martijn J.H. Doeleman , Anne-Fleur Koster , Anouk Esseveld , Hans Kemperman , Joost F. Swart , Sytze de Roock and Wouter M. Tiel Groenestege ORCID logo EMAIL logo

From the journal Clinical Chemistry and Laboratory Medicine (CCLM)

doi.org/10.1515/cclm-2024-0812

Abstract

Objectives

This study examined the comparability of venous and capillary blood samples with regard to routine chemistry analytes.

Methods

Venous and capillary blood samples were collected from adult patients to assess comparability of alanine transaminase, albumin, alkaline phosphatase, apolipoprotein B, aspartate aminotransferase, total bilirubin, calcium, chloride, creatin kinase, creatinine, C-reactive protein, ferritin, folic acid, free T4, gamma glutamyltransferase, glucose, high density lipoprotein cholesterol, iron, lipase, lipoprotein a, magnesium, phosphate, postassium, prostate specific antigen, sodium, total cholesterol, total protein, transferrin, triglycerides, thyroid stimulating hormone, urate, urea, vitamin B12 and 25-hydroxyvitamin-D3. Furthermore, hemolysis-icterus-lipemia Index (HIL-Index) was measured for all samples. All measurements were performed using the Siemens Atellica® CH or IH Analyzer. Deming regression analysis and mean relative differences between venous and capillary measurements of each analyte were contrasted with the desirable total allowable error (TEa) and Clinical Laboratory Improvement Amendments (CLIA) 2024 proposed acceptance limits for proficiency testing.

Results

Deming regression and mean relative differences demonstrated excellent comparability between venous and capillary samples for most measured analytes.

Conclusions

Capillary and venous samples showed comparable results for almost all studied chemistry analytes. Of the 33 studied analytes for which TEa criteria where available, 30 met TEa criteria. CLIA 2024 criteria where available for 29 of the studied analytes of which only glucose did not meet the criteria. In conclusion, capillary blood draw is a suitable alternative for venous blood sampling for measuring most of the investigated analytes. This benefits patients with fear of needles and might pave the way for remote self-sampling.

Keywords: chemistry analytes; capillary sampling; finger stick; comparability; remote blood sample collection; alternative blood sampling

Open access here:

degruyter.com/document/doi/...

[tattybogle]

fT4 is on the list ..... or am i being thick ?

[helvella Administrator in reply to tattybogle]

No - that's my role.

I split my reading across the day and made a mistake.

[TSH110 in reply to helvella]

but no FT3 ☹️

[TSH110 in reply to tattybogle]

But FT3 is the most important one and it’s not there! Can we assume it’s accurate if the others are? I assume not.

[helvella Administrator in reply to TSH110]

Seems likely but I don't think it safe to assume anything!

[TSH110 in reply to helvella]

My thoughts too it's a real shame they didn’t test it

[helvella Administrator in reply to TSH110]

How about emailing them? I feel it is often worth pointing things out or asking why not. The worst that can happen is you don't get a reply.

[TSH110 in reply to helvella]

Good idea - we should all email them about it so they know in no uncertain terms it’s a big omission that’s really let us down

[TSH110 in reply to helvella]

Ok I’ve done it and emailed them about their omission of free t3 and asked them address it in any future reach of a similar nature.

If I hear back I’ll let you know what they have to say.

[TSH110]

useful to know. I’ve had problems with foliate and one other with the finger prick test

[helvella Administrator in reply to TSH110]

For folate, I don't think it is the draw that is the problem - more the time and possible damage between the draw and the analysis.

[TSH110 in reply to helvella]

Yeah they said the cells had exploded or similar I did struggle to get the sample out which would not have helped. Even with the downward plank method they were no good either.

but my venous draws with NHS have read it ok Perhaps they are better transported by the nhs rather than via the mail system?

[TiggerMe Ambassador in reply to TSH110]

Squeezing the finger is often where the damage occurs