Finger prick test

Hi please can I ask is the finger prick test as accurate

As the drawn blood I'm sure My hyper has come back but don't want to go to GP because if it hasn't I need to see her for what is wrong in the past when I have asked her to check things she gets funny and says it's nothing just menopause see I'm getting anxious and paranoid I'm not normally but I got like this when I was last I'll I just can't see that a finger prick test could be as good as when blood is drawn they take so much more

Thanks

32 Replies

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  • Rush2112, I believe they are just as accurate, after all, it is the same blood whether it drips out of your finger or from your arm :)

    You just need to be able to squeeze out of your finger the amount of blood required to fill the little container that they send you.

  • I wanted to ask this same question, because I also think that finger prick tests can't be as accurate as those that are done normally (from vein).

  • If you do a finger prick test it shows something is wrong, and your GP is too thick to realise that the labs are accredited to the same standard as NHS labs/or it is an NHS lab doing private work, then the GP will repeat the relevant tests.

  • EleonoraT,

    Rush2112 was asking about thyroid tests. I don't think you should apply your experience with the GTT to thyroid tests, they are very different.

  • I have done lots of finger prick tests for various things, only one I found inaccurate was for Vitd and that was a blood spot on a card jobby, all others done by finger prick and filling a tube have shown same results as normal blood tests done at GP or hospital. Just choose a reputable company and get it to them next day.

  • My cousin works as biochemist in a hospital. She told me that finger prick tests are not reliable for thyroid or any other serious tests. She explained why, but it was too complicated for me to remember. I am just sure that she is right cause it's her profession. And she is not some of those out of date guys who went to school some 50 years ago, she is 34.

  • There is a big difference between blood spot finger prick tests and the ones where you fill a small tube with blood, by squeezing it out of your finger yourself, instead of someone sucking it out of your arm. Blood spot tests are defintely useless for thyroid. The microtainer ones are widely and successfully used now here in the UK.

  • She said all finger prick tests are inaccurate, doesn't matter how much blood you squeeze. If you are not biochemist I prefer to believe in her opinion cause she went to school for this.

  • We have at least two blood test experts here on the forum. Perhaps they can clarify this question for all of us.

    BlueHorizonMedicals MyThyroidChecks

  • Not if they are making money from it. I guess stakiboy's cousin don't have anything from it if she works in public hospital, but he didn't say is it public or private.

  • It's public hospital, no she has no interest in saying that, she works for salary not for profit.

  • I have deliberately done bloods, both finger prick and normal way, at the same time to check accuracy and found no significant difference in results.

  • I guess they sometimes can show things but sometimes not, that's why I am sticking with my veins :)

  • bantam12 I have also done that but as yet haven't got the GP NHS results back. Both taken with 40 mins of each other.

    I had results back from BH the next day, but have been told that the NHS antibody tests can take several weeks as they batch despatch them. Not sure if this is a fob off or true - but it at least thwarts the notion of postal delay affecting the results which I imagine would be said of the private companies.

    Will confirm if they are the same when I get them.

  • Perhaps helvella could post a link to some relevant research. :-)

  • Always up for a research/search challenge... :-)

    I typed a few words into PubMed and got an interesresting grab-bag of things. Three of the most interesting of which I have posted below.

    The actual link to the search results was:

    ncbi.nlm.nih.gov/pubmed/?te...

    You can find the other 103 hits by following that link.

    J Pediatr. 2015 Apr;166(4):1013-1017.e2. doi: 10.1016/j.jpeds.2014.12.035. Epub 2015 Jan 31.

    Screening for hypothyroidism in Down syndrome using the capillary thyroid stimulating hormone method.

    McGowan S1, Jones J2, McMillan D3, McLaughlin K4, Smith S4, Leyland K5, Charleton P6, Donaldson M7; Scottish Down Syndrome Screening Group.

    Collaborators (41)

    Estell A, Brown A, Mackenzie J, Brown A, Rahim M, Williamson S, Cordeiro N, Clark C, Houston J, Allan L, Russell S, Strong P, Gibson H, Bryson S, Duncan A, Rayen B, Shyam R, Weighland E, Bath L, Somasundaram S, Smith R, Goh D, Logie L, Caldwell J, Yates J, Barlow H, Mansor M, Schulga J, Pyper A, Docherty E, Shaikh MG, Mason A, Dunbar T, Watt S, Farmer G, Campbell A, Hunter I, Scott L, Greene S, Lawlor K, Cormie C.

    Author information

    1Section of Child Health, Royal Hospital for Sick Children, University of Glasgow School of Medicine, Yorkhill, Glasgow, United Kingdom.

    2National Health Service Greater Glasgow and Clyde, Royal Hospital for Sick Children, Yorkhill, Glasgow, United Kingdom.

    3Academic Unit of Surgery, Glasgow University School of Medicine, Royal Infirmary, Glasgow, United Kingdom.

    4National Health Service Greater Glasgow and Clyde, West of Scotland Genetic Services, Newborn Screening Laboratory, Southern General Hospital, Glasgow, United Kingdom.

    5National Health Service Greater Glasgow and Clyde, Southbank Development Center, Glasgow, United Kingdom.

    6National Health Service Grampian, Royal Aberdeen Children's Hospital, Aberdeen, United Kingdom.

    7Section of Child Health, Royal Hospital for Sick Children, University of Glasgow School of Medicine, Yorkhill, Glasgow, United Kingdom. Electronic address: malcolm.donaldson@glasgow.ac.uk.

    Abstract

    OBJECTIVES:

    To analyze data from the Scottish capillary thyroid stimulating hormone (TSH) screening program for hypothyroidism in Down syndrome to identify a threshold for capillary TSH elevation below which low venous free thyroxine (fT4) (<9 pmol/L) and/or frank venous TSH elevation (>10 mU/L) range is unlikely.

    STUDY DESIGN:

    Review of proformas prospectively submitted on all children with Down syndrome referred via the screening program between 2003 and 2013.

    RESULTS:

    Ninety-nine patients with Down syndrome (50 females, 49 males) were identified, 76 school-age (≥ 5 years) and 23 preschool (<5 years), mean (range) age at referral 9.4 (0.9-18.1) years. Pearson correlation between capillary TSH and venous TSH was 0.814; between capillary TSH and venous fT4 -0.522 (P = .01). Receiver operator curve analysis showed that capillary TSH values of 4 and 6 mU/L were 95.9% and 73.5% sensitive, 5.8% and 80.8% specific, respectively, in predicting venous TSH >10 mU/L. Fifty-three children had capillary TSH values of 4-5.9 mU/L of whom only one, a boy of 15.8 years, had subnormal venous fT4 (<9 pmol/L), and venous TSH >10 mU/L was found in 13 (4 preschool).

    CONCLUSIONS:

    Venous fT4 is normal in almost all patients with Down syndrome with capillary TSH 4-6 mU/L. We propose an algorithm incorporating rescreening by finger prick after 6 months, rather than venepuncture, in school-aged children with borderline capillary TSH elevation. Further data are needed before this approach can be recommended for preschool children.

    Copyright © 2015 Elsevier Inc. All rights reserved.

    PMID: 25648292

    DOI: 10.1016/j.jpeds.2014.12.035

    [PubMed - indexed for MEDLINE]

    ncbi.nlm.nih.gov/pubmed/256...

    Vaccine. 2016 Oct 17;34(44):5306-5313. doi: 10.1016/j.vaccine.2016.09.007. Epub 2016 Sep 15.

    Gene expression profiles are different in venous and capillary blood: Implications for vaccine studies.

    Stein DF1, O'Connor D2, Blohmke CJ3, Sadarangani M3, Pollard AJ3.

    Author information

    1School of Clinical Medicine, University of Cambridge, United Kingdom.

    2Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom. Electronic address: daniel.oconnor@paediatrics.ox.ac.uk.

    3Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.

    Abstract

    BACKGROUND:

    Detailed analysis of the immunological pathways leading to robust vaccine responses has become possible with the application of systems biology, including transcriptomic analysis. Venous blood is usually obtained for such studies but others have obtained capillary blood (e.g. finger-prick). Capillary samples are practically advantageous, especially in children.

    METHODS:

    The aim of this study was to compare gene expression profiles in venous and capillary blood before, 12h and 24h after vaccination with 23-valent pneumococcal polysaccharide or trivalent inactivated seasonal influenza vaccines.

    RESULTS:

    Gene expression at baseline was markedly different between venous and capillary samples, with 4940 genes differentially expressed, and followed a different pattern of changes after vaccination. At baseline, multiple pathways were upregulated in venous compared to capillary blood, including transforming growth factor-beta receptor signalling and toll-like receptor cascades. After vaccination with the influenza vaccine, there was enrichment for T and NK cell related signatures in capillary blood, and monocyte signatures in venous blood. By contrast, after vaccination with the pneumococcal vaccination, there was enrichment of dendritic cells, monocytes and interferon related signatures in capillary blood, whilst at 24h there was enrichment for T and NK cell related signatures in venous blood.

    CONCLUSIONS:

    These data show differences between venous and capillary gene expression both at baseline, and post vaccination, which may impact on the conclusions regarding immunological mechanisms drawn from studies using these different sampling methodologies.

    Copyright © 2016 Elsevier Ltd. All rights reserved.

    KEYWORDS:

    Genomics; Immunity; Systems biology; Vaccines

    PMID: 27642133

    DOI: 10.1016/j.vaccine.2016.09.007

    ncbi.nlm.nih.gov/pubmed/276...

    Optom Vis Sci. 2014 Apr; 91(4): 452–458.

    Published online 2014 Mar 27. doi: 10.1097/OPX.0000000000000188

    PMCID: PMC4189593

    Patient Acceptability of Tear Collection in the Primary Healthcare Setting

    Joanne Hui Min Quah,* Louis Tong,† and Sylvaine Barbier‡

    Thyroid eye disease, also known as Graves’ ophthalmopathy, is a characteristic feature of Graves’ disease. It is associated with enlargement of lacrimal gland19 and ocular surface diseases such as dry eye.20 A raised tear IgA-to-lysozyme ratio was seen in patients with thyroid eye disease,21 which suggested the involvement of the lacrimal gland. This involvement occurred more often in patients with a long history of the disease. The levels of zinc-alpha2-glycoprotein and lactoferrin were increased in tears in patients with thyroid eye disease.22 The levels of NGF were also higher in patients with thyroid eye disease than in controls and significantly decreased after 2 to 4 weeks of steroid treatment.23

    ncbi.nlm.nih.gov/pmc/articl...

  • Thanks for the search - I imagined you'd already have the relevant details in your personal data bank. ;-)

    There are some surprising conclusions here, not least the difference in gene expression.

  • Searching afresh is a good thing for me. I find things that weren't there, or I ignored for some reason.

    Also, I feel that providing a "what I did" might just encourage someone to dive into PubMed or elsewhere and see what they find. :-)

  • Yes, I can find PubMed a bit bewildering when I'm having a foggy day/week, so encouragement appreciated. :-)

  • Thanks for all your replies although I think im more confused than before lol

    I'm tempted to just as GP to do tests I know they will as I was very poorly before the only problem is. Getting nhs to do t4 if tsh is even slightly in range and my tsh was in very low range of 0.4 for a long time and didn't drop to -1 until I had heart problems it was only then t4 was checked

  • Hi Rush,

    As Bluebug says, if the tests show something wrong then your gp should repeat the test at the very least.

    My new gp has treated me from my results. My last gp was horrible about them but agreed to retest himself.

    If that happens at the very least then it would be money well spent :)

    People in the medical profession disagree all the time. I researched this same question before deciding to go ahead with mine. I read that finger prick blood is actually more accurate as its using blood that is getting to the cells. Blood from a vein is returning to the heart/lungs to be refilled so has already "dropped off" nutrients to the cells. (I'm not saying if this is true or not.)

    I can't find the exact paper but a quick google brought up this which evidences dried blood spot tests and as you've seen here most people agree they are rubbish. (I haven't checked the reliability so please don't read this and go after dried blood spot tests) verywell.com/capillary-fing...

    My point is that for most studies that find evidence for something there will be ones who find evidence against. You then have to scrutinise every word and sentence for bias and make your own decision as to who's study and method is more reliable. On top of this there could be hundreds of studies for the same subject. So unless you find someone independent and reliable who has done a systematic review of each study available, unfortunately one biochemist may have read one study against it yet another company could point you to evidence for.

    It really is just weighing up the risk of the money for you. Nobody knows your circumstances. If it was to come back with something your gp hadn't found and got treatment started for you then it would be worth the money or you wouldn't be considering it. If it comes back with something but your gp wants to repeat the test before treating then that should be worth it too. Then if it came back as not finding anything it's deciding if the money was worth the peace of mind or to be in the same position with your gp but knowing you tried. At the end of the day you don't HAVE to share the results if you don't want to.

    Definitely take on board what everyone says and what evidence they offer but I just wanted to explain this as it can be confusing when people disagree :) there was even a post on here where someone had blood drawn from the vein at two different hospitals and it was found the first hospital had been giving inaccurate results. Nothing is 100% it's just if it's worth it for you :)

  • Thanks Melissaemily

    I know what you mean my daughter has lupus and we have found inconstancy if blood is taken at GP I wonder if it is because of time spent going to lab she has found most postive ones come from hospital and sometimes a GP has a postive then retested at hospital its negative she now will always have test at hospital to make sure results are constant

  • I don't know enough about blood tests to be honest but I guess the most important thing is consistency :)

    I wish both you and your daughter well.

    One thing I will say is there are more people on here who are glad they went ahead with the finger prick tests than say they wish they hadn't :) the amount of positive results and returning customers on here is what helped me make my decision.

    You can also have venous blood drawn privately and sent to the same labs as the finger prick tests if you're concerned about accuracy x

  • I did notice a fairly recent paper which claimed that the results were almost completely unchanged by being stored before analysis. Obviously, that will depend on how stored, how long, whether they used the right extra ingredient(s) in the tube, etc., but it seemed fairly reassuring.

    Will try to re-find it and post.

  • I think like this - if tests can be properly done from finger why even most modern hospitals would be still "piercing" our veins?

  • Moggy35,

    It depends how many tests are ordered and much blood is required. Only a microtainer of blood can be obtained from finger prick blood testing (and some people have trouble filling a microtainer) whereas a larger vaccutainer or multiple vaccutainers can be obtained from a venous draw.

  • I don't think that I would be ever able to squeeze enough blood from my finger for any test :) Often I can't get enough even for my glucose meter!

  • There has been research on extremely minute blood drops used for tests. Particularly targetted at people who are having a succession of tests (imagine having FT4 and FT3 tested every half hour for two days).

  • I think I agree with you and at the end of day it's only £40 more to have it done at spires so I think I'll go down that route

  • If you have to buy your own medication like many here do, then £40 would help to pay for that instead :)

  • moggy35 It doesn't make sense in a hospital to do fingerprick tests. Phlebotomists are expereinced and can do the venous draws really quickly. Making someone squeeze it out of their finger would take much longer. The finger prick tests are for convenience of individuals doing it themselves. I live in a remote location and if I want a private blood test I'm probably going to have to do the fingerprick one or nothing. I don't see why they can't be accurate.

  • An excellent question, and some great answers!

    Capillary blood sampling is used commonly for blood glucose measurements for diabetic monitoring, as well as INR coagulation readings for those taking Warfarin, so the clinical reliability of it is, in my view, beyond doubt.

    Studies show that state that one drop of Capillary blood has a high rate of variability when compared with a venous sample. Two drops, less so. However, when the sample volume progesses past two drops of Capillary blood the variability almost diminishes completely.

    As a Microtainer/Minicollect tube takes about 15 drops of blood (plus or minus a few) enough sample is collected for the World Health Organisation, NHS to deem it a viable collection method, which is why Laboratories and Biochemists offer it as a reliable way of collecting a sample.

    If in doubt then vacutainer kits can be requested for a more traditional way to collect a sample, although then there is the matter of finding a phlebotomist!

    NHS hospitals will always use a vacutainer because that is most convenient, and the need to collect enough sample is paramount without having to worry about "finger failure"!

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