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A useful guide to blood tests

Discussion in 'Community Submitted Guides & Links' started by hanadr, Feb 16, 2009.

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  1. hanadr

    hanadr · Expert

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    I hope I got everything right and that folks find this useful. If you want me to research any others, I'll do so willingly
    Enjoy!
    Hana
    Explaining the routine blood tests


    1) Finger stick test or BG test
    The glucose in our blood, which is there largely as a result of what you have eaten, (your liver may have made some), circulates in solution in the plasma, which is the liquid fraction of the blood.
    The average blood volume of humans is about 4.7 litres, slightly more for men and less for women and children. It accounts for about 9% of body weight
    In Britain, we measure concentrations of solutions in “Moles” 1 mole of glucose weighs180grams, or about 1/12th of a standard bag full. To make the numbers simpler, we measure blood glucose concentration in millimoles per litre A millimole is one thousandth of a mole so a millimole of Glucose weighs0.18grams
    So if a non-diabetic has a blood volume of 5 litres and a blood glucose of 4.5 mmol/l the total weight of glucose in that person’s blood is 0.18 x 4.5 x 5 grams or 4.05grams, which is about a teaspoonful.


    2) Hb A1c or A1c test
    Haemoglobin is a wonderful molecule It has the ability to pick up and put down oxygen and thus to carry it from the lungs to where it is needed.
    Haemoglobin in blood is confined within the red blood corpuscles (they shouldn’t really be called cells, because they have no nucleus. But we all do it :>))
    A red blood corpuscle with its enclosed haemoglobin lives about 120 days and then it’s dismantled and recycled
    Haemoglobin also sometimes picks up other molecules than oxygen, including carbon monoxide. or glucose. These it cannot put down again. Once attached, they stay to the end of the corpuscle’s life.
    The higher the concentration of the “passenger” molecules, the more is picked up by haemoglobin. Thus if you have a lot of glucose circulating in your blood, the Haemoglobin will pick up a lot of it. Once bound to haemoglobin, a new compound is formed called Glycosylated haemoglobin shortened to HB A1c
    It was only realised about 30 years ago that the percentage of haemoglobin that is glycosylated, could be used to show how high the concentration of glucose in the blood had been during the lifetime of the red corpuscles (120 days) some people have worked out a correlation of average BG values to HbA1c values
    The equation quoted in Bernstein’s book is:
    Average BG reading = 35.6 x HbA1c – 77.3 (Those units are in mg/dL)
    This is a bit complicated to do all the time and there are plenty of tables available on line.
    No calculation works very well for HbA1cs of less than 5%

    3) c-peptide test
    C-peptide (connecting peptide) is the Glue, which sticks the A and B strands of pro-insulin together. It is released into the bloodstream when the insulin is made from Pro-insulin. The amount of c-peptide mirrors the amount of insulin being made.
    Usually in T1 diabetes, there is little insulin production and so there is little c-peptide present. On the other hand, T2 diabetics often make a lot of insulin in an attempt to overcome resistance.

    Lipid profile test
    Lipid is a scientist’s word for fat. Cholesterol is a kind of lipid, which is made in the liver. It used to be thought, from dietary fats, but is now known to be made from carbohydrates. Cholesterol is carried around the body by transport molecules. LDL or low density lipoprotein and HDL or high Density lipoprotein. LDL is thought to deposit its fat in the blood vessels and clog them. HDL is thought to clear them up. When you get HDL and LDL cholesterol measured, it’s better to find you have lower amounts of LDL and higher amounts of HDL.
    We also circulate a type of fat called triglyceride. These arise in the liver from food we eat and the amount varies throughout the day. That’s one reason this blood test is done after fasting. Triglyceride levels should be kept low.



    Millimoles

    the mole is a useful Value when calculating around chemical reactions . Essentially, it's the Relative Atomic Mass of the atom or molecule, in grams. Where 1 hydrogen atom has an RAM of 1,a mole of hydrogen weighs a gram carbon RAM is12 a mole of carbon weighs 12 grams, Water RAM is 18,a mole of water weighs 18grams Glucose RAM is 180so 1 mole weighs 180grams.. It all comes down to the Periodic table and Avagadro's number( good fun!! :lol: !!)
    Americans and most of the rest of the planet have decided to work out their blood chemistry in actual masses, so their values for BG are in milligrams per decilitre NOW do you see why the conversion factor is 18? :lol:
    Yes I know I'm nuts,(almonds perhaps?) but I love this stuff.
     
  2. sugarless sue

    sugarless sue · Master

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    Thank you Hana,very helpful.
     
  3. Patch

    Patch Type 2 · Well-Known Member

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    Fantastic! This should be on page one of the manual.

    Sticky, please!
     
  4. sugarless sue

    sugarless sue · Master

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  5. JohnnyAngel57

    JohnnyAngel57 · Well-Known Member

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    Hy, I don't know why but I always seem to forget what the blood sugar limits are on which its ok. Is it 3.0 - 10.00 or 11.00. I always seemed to be around 4.5 - 3.1 going up to 7.1-8.0 at night, but lately I always range now between 7.0-9.0, though I admit I've been a bit naughty on the food side, as I've been having frozen chips (low fat) and potatoes with each main meal I have one a day, and my brekkie is usually a large cereal with skimmed milk. I can't even say I've been enjoying myself with alcohol as the chrissy stuff has gone not that there was much so it just seems to be the food and lack of exercise, though that is because of my back and legs.

    One question I might have asked here but not sure is my monitor checks. What if I have a cold or hot drink do I have to wait another 2 hours before I can do a test or can I still go for my original time, it just seems a long time to do without a drink; I love my earl grey.
    cheers,
    John
    PS: I forgot to mention I'm T2 diet only or should I say lack of diet only lol :D
     
  6. hanadr

    hanadr · Expert

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    Since a non-diabetic blood glucose is about 4.7at all times, with few spikes or troughs, That's a good target to aim for. It is believed, with some evidence, that 7 is the level at which vascular damage begins. Glucose above that level is toxic to blood vessels. Thus logically, below 7 is the maximum that a well controlled diabetic will permit. As a diet only, T2, I would recommend the "eat to your meter" approach. Sorry I can't remember the link
    The levels advised by many healthcare professionals, were decided on by guess work and a fervent belief that patients are non-comliant and that was the best anyone could achieve.
    We now have evidence, knowledgeable and committed patients and we can do better. We are ahead of most professionals in this game.
    If you want the most academic and useful book on the subject,the "bible" is Dr. Bernstein's diabetes solution. He's American, so the units are in mg/dL. ( conversion factor is 18) ours are mmol/l
    Check out my Sticky on the millimole.
     
  7. Stuboy

    Stuboy · Well-Known Member

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    finally i know what a c-peptide test is!! thanks :D

    Although i disagree about non-diabetics being 4.7 most of the time, any time my girlfriend tests or my sister, they are 5.5ish - everytime! But then we are all different...

    I have a sheet from the JIGSAW course i just finished with the BG profile of a non diabetic... taken from CGM, there are spikes around meal times, but dont last as long as a diabetic... i'll scan it if you like and post it up? Might be useful to some to see.
     
  8. catherinecherub

    catherinecherub · Guest

    Yes please Stuboy, I would like to see that. I know that I have tested family members and their readings prior to food are excellent but food does make them spike.
    Catherine.
     
  9. EricD

    EricD · Well-Known Member

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    Boy, is this diabetic stuff complicated! :?

    Everywhere I read or get told by the experts I get different results.

    My DN says 4-8, my GP says 4-9, 4-10 on other sites, here I read above 7 is dangerous. :?

    Before my 50th the only "moles" I knew of were the ones that dug up peoples gardens and "carbs" were a part of a petrol engine.

    Hana, thank you for the explantions, makes things a little less complicated, I think. :? :lol:
     
  10. hanadr

    hanadr · Expert

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    Hi Eric,
    I had to teach the Mole as a concept to kids for years. then someone "wiser" than I decided to remove it from the syllabus. Pity, it's a useful concept and not actually difficult. I don't understand why it's used in bvblood sugar determination in the Uk, when Americans and most of Europe manage perfectly well with milligrams per decilitre. Ok the numbers are 18 times bigger, but the gram is an easy unit to eork with. You don't have to understand that whereas a mole of Glucose weighs 180grams. a mole of salt weighs58.5grams.
    What I love about moles is that at standard temperature and pressure, a mole of any gas occupies 22.4litres.
    I did once catch one of those"little gentleman in a velvet jacket". That fur is wonderful. No! I didn't get bitten.
     
  11. Dennis

    Dennis Type 2 · Well-Known Member

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    Hi Eric,

    Those figures could all be correct. For a non-diabetic 4mmol would be about as low as they would go on average. 8, 9 or 10mmol would be as high as they would go when BS is at its peak at around 1 hour after a meal. Whether it is 8 or 9 or 10 would depend entirely on how much carbohydrate they had eaten and on the GI of the carbs (i.e. how quickly they convert from carb to glucose).

    Levels that remain above 7 for long periods of time are regarded as dangerous because 7.5 is generally regarded as the level at which diabetic complications begin (eye and nerve damage). That doesn't mean an occasional reading of above 7.5 is dangerous - we all have those, probably several times a day. It is where your BS level remains above the danger level for weeks at a time that the problems start.
     
  12. samcogle

    samcogle · Well-Known Member

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    Oh dear, this is a bit worrying as my blood sugar has yet to go below 7. My last fasting test with the doctor was 9...he put me on 1 metformin a day and waved me off into the sunset. I have been checking my own blood and it ranges from 8 up to 14. Should I get back in touch and hassle him?
     
  13. Dennis

    Dennis Type 2 · Well-Known Member

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    Hi Sam,

    Metformin itself doesn't significantly reduce blood sugar levels. What it does is to reduce insulin resistance, which helps the insulin your pancreas produces get used more efficiently. What you need to do to help the process is to reduce the amount of carbs in your diet. That in itself will lower your BS and give your pancreas a better chance of dealing with what you do eat. How much to reduce depends on how much and what type you currently consume, so if you could give us an indication of what a typical day's food intake would be (including drinks and snacks) then we might be able to suggest where you can make improvements.

    The good news about diabetic complications is that usually any damage that has already been caused can be reversed by getting your BS levels down to the safe zone. It's where people run very high levels over a long period that the complications can become irreversible.
     
  14. samcogle

    samcogle · Well-Known Member

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    Hi Dennis, I tend to eat either 2 slices of rye bread, dry with cinnamon or quaker oats with water and blueberries for breakfast (I am trying to follow a vegan diet, I was a veggie but I want to cut out all animal produce). For lunch I usually have left-overs from the night before, so home-made lentil curry with a small amount of brown rice or veggies with hummus or a salad with some sort of beans on it, lemon juice and a little olive oil. For tea it is lentils, tofu or beans with a small amount of wholewheat pasta, pasta or couscous with some form of home-made tomato sauce and veg like broccoli, carrots, etc. As the metformin has significantly reduced my hunger, snacks tend to be some form of fruit or a small bag of twiglets which I love and have decided they can't be bad as they are baked :)
    My only drinks now after cutting out all diet fizzy drinks, are water and black tea. I allow myself the odd cup of decaf coffee.
    How's this sounding? I think maybe I need to cut the carbs a bit more?
     
  15. Dennis

    Dennis Type 2 · Well-Known Member

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    Hi Sam,

    Your diet appears to be almost exclusively carbohydrate, and some of it extremely high GI carbs. I appreciate that you are attempting to take the vegan route, but whether you are a meat eater or not, your diet needs to be balanced with much more protein, and the carbs need to be lower GI. I could itemise each item for you, but you won't learn very much that way. Why not get yourself a copy of the Collins Little Gem Carb Counter book. Then you can see for yourself where all the carbs are and what alternatives you can consider. The book also has a section for vegetarians and sample meal plans.

    PS Twiglets are a definite no-no. Yes they are baked, just like all other wheat based products! Its not how they are cooked, its what's in them!
     
  16. phoenix

    phoenix Type 1 · Expert

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    Hi Sam,
    I think it is quite dificult for omnivores to advise people who are vegans. Dr Neil Barnard advocates a vegan diet for diabetes. He has an internet presence and the obligatory book. It is not a low carb diet, his approach derrives from the thesis that animal fats are themselves the cause of the problem. I know there are many that would dispute this, however he has enough credibility to have published a diet study in one of the ADA professional journals.
     
  17. samcogle

    samcogle · Well-Known Member

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    Yes that is the name of the guy whose book I bought and was rather impressed with. He doesn't say how long you should stick with it and does say it may not work for everyone. I have followed it for nearly a week and it seems not to be working so far.
     
  18. samcogle

    samcogle · Well-Known Member

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    Once I read back what I had typed I thought it looked a bit high. Thanks I will get that book and :cry: for the lack of twiglets , I just saw the wholewheat flour and the high in fibre and got excited...oh well.
     
  19. Apricot

    Apricot Type 2 · Active Member

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    Thank you for the easy peasy guide to tests. I think i have it...but i couldnt explain it...

    Now I have been keeping averages over the last few weeks....and it was 6.3, 7.5...and last week...8.2. So a marked deterioration.

    Still watching what I eat carefully, still taking 2 x 500mg metformin SR,....totally confused, always cold and hungry. Have kept a food diary.

    Have my first 6 month review on monday.

    Yours,
    confused of wakefieldish

    Apricot
     
  20. samcogle

    samcogle · Well-Known Member

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    Hi, it's of no help, but I am confused too. I think we have to be patient. The good thing is the metformin appear to have got rid of my hunger. I was on 2 but the doc said to start on 3 if there were no improvements in my levels, so today I started on 3 but there is no difference yet. I suppose that our bodies have to adjust and it is not going to be an immediate change (I am sure someone who is more knowledgeable will be able to correct me if this is wrong). I have quite a bit of weight to lose so am hoping as that drops things will alter sugar wise. Good luck with the review and let us know how you get on :)
     
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