If you are vitamin D deficient, what have you been prescribed?

[whowantsadog]

I've recently found out that my vitamin D levels are so low that it's not possible to get a reading on them (apparently below 30 doesn't register?) However, when I've collected my prescription they seem a much lower dosage on prescription than what I bought last week in Sainsbury's, and on googling it seems people are taking doses of around 5000iu for similar deficiencies. Do I need to double up? (Picture shows prescription on left and over the counter on the right).

I'm also hoping that you're going to tell me that getting your vit D levels back up transformed your life, helped you drop 2 stone and stopped you feeling 90 years old?

hi again mint !

                            Well,  it seems , from your explanation ,  that 4000 IU  per day for a month improved things ,  and then  roughly  1500 IU  per day  allowed your level to slowly decrease again over a couple of months.  In other words your body requires a number  higher than 1500 IU  per day.   That number is what you need to establish.  It could be 2000 IU  , it could be  3000 IU  , it could be 4000 IU  per day ,  every day. 

                    The amount we need to maintain  healthy vitamin D levels depends upon lots of factors ,  which include  BMI ,  your ability to absorb in the gut ,  how much sun you get on skin , what time of day , what time of year, skin colour.   Now,  in the UK,  and as  someone living a western lifestyle , it is difficult to get much vit D from sunshine.   You must be outside exposing large areas of skin , in strong sunlight  , between 11  and 3 pm.  IN Summer.    In winter , it  will not  make any vitamin D , the sunlight is too weak.  As I explained above.
 In your circumstances , where you know you do become low , I would take Vit D every day, perhaps only dropping back by 1000 IU  per day  when you are on  a sunny holiday, or sunbathing a lot in mid summer. 

You asked about sun derived vitamin D , It does remain longer in the blood , than supplements . Up to twice as long ,i.e. 60 days half life. BUT don't forget , it is still being used up, every hour of every day , you need to continuously receive more vitamin D to keep your level acceptable, whether that be from sun , supplement or food. See my bucket analogy , up above in this thread !

Now there is not much Vit D , in western food , and you would be highly unlikely to get your requirement solely from food.

It would seem to me ,  that now you have been on your average dose of about 1500 IU  per day  , for a couple of months you could check your blood level,   either by doctors test ,  or that lab ,  I mentioned above in this thread.    It will tell you  at what blood level your symptoms  have come back.    It will also give you a good idea about how much you need to take ,   in addition to what you are taking now.       Lets suppose your blood level is measured as 50 ,   then to get to 100 ,  you will need to take an extra 2000 IU  daily   , on top of what you are taking now.   Then measure again in  2  to 3 months.  To see ,  if your level has reached  where you expect.         On average ,  an extra   2000 IU  per day ,  will raise blood levels by 50 .    BUT  we are all different.  Checking , makes so much sense.   

  You may find that your doctor is not too interested in repeated measurements …. it costs money  and they don't have much.  

  As an alternative ,   you could just  go back on  3000 IU  or 4000 IU  per day .   Then measure, after a couple of months.   There should be no problem with that . You have already done it once , and it improved things.  You know you are on the right track !      Those numbers are not excessive ,   they  are in fact the sort of numbers we mostly need to keep our vitamin D levels up around 120   ish.  Some people with higher BMI s will need even more.

      Don't forget …  keeping a good vitamin D level is critical for good health ,  a low level over the long term can lead to quite a few nasty diseases.  It is important that you look after yourself. !

  Best of luck .  

If you need any more info, just get back to me

         BTBH. 

PS. Don't let the doctor tell you that by having the treatment you have had , there is nothing more he can do. If he says a level of 50 is enough , then don't accept it, especially now your symptoms have come back. Look above in this thread , where endocrinologists say 75 is a minimum. And 120 is good.

Hi BTBH.
Thanks for all the detailed advice. I will see how it goes on a higher dosage of 4000IU first and then retest.

Hi, I've suffered vitamin D deficiency and been treated successfully for it. However, I thought I would also mention that your symptoms can sometimes be associated with thyroid issues. I was hypo (too low) thyroid, and take thyroxine after being diagnosed with Hashimoto's (thyroid disease) about 9 years ago. It might be worth asking for your thyroid levels to be tested. I have painful hands and feet especially on waking it despite my vitamin d levels being perfect (I'm under a Consultant Endocrinologist, who recommends at least 100 reading of vitamin D, through NHS)

[it] typo

My result was 15. I’m on 20,000u twice weekly for eight weeks then 1000u daily, probably for life. I too am hoping that when my result is normal I’ll no longer feel like a 90 year old.

Thanks Nettleskeins. Yes I was tested for thyroid levels too last April, and it came back fine. But I will certainly keep it in mind, should things not improve after a few weeks from increasing my dose of vitamin d.
AlexaAmbidextra-my doc never told me what to take after my loading dose, which is why I am experimenting with what dose to take. I too, do not want to feel like an old woman.

Hi everyone, finally got my test results today and my vitamin d was 32. Been advised to take supplements (cheaper to buy over the counter than get a prescription!)

Anyway I've bought 25mg, is this OK? Was really confused (mind fog not helping!( because there was a few different strengths so I went for the middle option!

Grateful my thyroid was fine but hoping I really begin to feel better soon!

25mcg is very little if you are as low as 32. It is equivalent to 1000iu. When I was at 35 reading, I was given a massive booster supplement by the doctor, about 20,000 iu per week to get my levels up before taking a ^maintenance* dose of at least 25mcg a day. But in reality I was told to take 2,000iu (or two 25mcg tablets) a day for the forseeable. (Having a thyroid condition as well, may be why they said this)

The government recommends 1000iu a day for every adult in the winter months as a maintenance dose, so you need a booster or loading dose first. We've just had summer so to have such low levels already, means that in the winter it may get worse! Go back to your GP and ask him to look up what the NICE recommendation is for a loading dose.

Hi mindfull ,

                          Unfortunately, it seems ,  you have been caught up in a rather awkward situation ,  whereby there is no agreement between various NHS areas,  even within areas , about Vitamin D , and the desired blood level, and the necessary doses to satisfy our need for this vital micro-nutrient. 

        I know it is not much help to you ,   to see so much conflicting medical advice , that has been meted out to various posters , by members of the medical profession over dozens of threads here on Mumsnet concerning Vit D. 

          One school of thought, has lead to a  policy as follows:

Adequacy is 50 and up to 200 , between 25 and 50 is insufficient and under 25 is deficient. Referring to blood levels of Vit D in nmol/L , i.e. the UK test. The policy is , that only deficiency should be treated , by prescription. That means if you are above 25 and below 50 , you should be advised to treat yourself with over the counter supplements. BUT crucially , the amount of supplementation is not set , otherwise it would be a prescription . So you are left in the dark. YOU have been treated according to this policy. Unfortunately this is a very poor erroneous policy ... and IF you had been lucky enough to get to a more enlightened practitioner , ( Such as Nettleskeins endocrine consultant ) you would have been advised to get a blood level of over 100.

 Fortunately .. throughout the NHS ,  things are very slowly changing ... the blood levels thought of as sufficient have been rising ...till now ,   75 is considered a minimum in some areas.  Obviously not your area yet.  

        IF  I was you, I would try to get my blood level above  100 ,  by supplementation .     As I have posted here before , in this thread,     ON AVERAGE ,  if you take 1000 IU  ( 25 microgram )  per day  daily ,  in the long term ,  then your blood level will rise by  25   nmol/L.  Your level needs to rise by  75 ,   hence   3000 IU daily supplementation would be suitable. , ( i.e  75   microgram ).

                         Another policy from which you might fall foul ,  is  the   " not to re-test policy" ,  whereby it is assumed that any dose of supplement will have the desired effect.  This is not necessarily true. We all have differing responses to supplementation ,  by a factor  of up to 6  to 1 .      However ,     it does save money - Not  to Retest.   but it is not necessarily the best for you.   You need to find out what your blood level becomes after three months ,   then adjust , if necessary ,   your supplementation. 

Up above in this thread , I posted the site for an NHS lab, which will test your level from a bloodspot sent by post, on blotting paper, they email your result in a week. Unfortunately , if the test is not doctor ordered , ( which he might not do ), they will charge £29.

   Best of luck ,  

BTBH

     PS.   I have posted quite a bit here on Mumsnet ,  about vitamin D ,    lots of interesting threads  ,    or just get back to me , if you want any more info.

.

My gp has put me on 25,000 altavita vitamin D twice a week for 8 weeks then weekly. My vitamin D level was 42, it has been 11.2 or 11.9 in the past. I'm just wondering how long it should take me to get my levels up to over 100 approx.

Hi honey ,
We all have different responses to supplementation , by a factor of 6 to 1 . Therefore it is important that we measure our response , in order to know where our blood levels are. Ultimately, the beneficial effects of vitamin D , are related to your blood level, not the amount you take.

                      That said ,    with your current dose of  50,000 IU  per week ,   ( 1.25 milligram which is 1250  micrograms))  , which translates to approx   7000  IU  per day.   ..... then an average responder would expect to reach around  150 - 180   nmol/L    after  60 to 90 days , on that daily dose.  You would then be  in equilibrium.   after that time .  As your blood level rises ,   your response to additional vitamin D becomes less.      So lets say you reach 100 ,   then  it takes more supplementation per unit rise in blood level.      This is the reason it is very difficult to become toxic with Vit D supplementation.   It has never been seen , in the medical literature with doses of less than 30,000 IU  per day ,    or blood levels below 500 nmol/L.  

                  So whilst we cannot be exact ,   because we are all different ,    during an 8 week course of  50,000 IU , from your base of 42 ,    an average responder is liable to reach 100   in  4  to 5 weeks possibly a little longer .

                  I wonder why you need to know that information , ?    You may be thinking that once you reach that figure, your symptoms  of deficiency will suddenly stop.  However ,  you must realise that the symptoms have arisen because your cells have not been working as well as they could have done , over a long period of time,   i.e all the time you have been low in Vit D.  This will have had an effect on your body , which will now start to be repaired. That repair may occur quite quickly ,    however , depending upon what has gone wrong ,  it may take longer.   IF  it is bone problems it could take 6 months or more.  That is why it is important to achieve a good level of vitamin D ,  and keep a good level.    That is why it is important to continue with some kind of strategy to maintain a good level., even after your loading dose has been stopped.  So your maintenance dose of 25000 IU  weekly , equivalent to  3500 IU  per day should do that.        You will not know for certain , unless you test your blood level,    after three months,  say, of being on  your 25000 IU dose.     Send to the lab posted above ,   if your doctor won't do it.      It is important that you don't just stop supplementing , without knowing what is going on with your blood level.  Incidentally  the lab will send test kits internationally  for an additional £5 .  That's very handy for expats, or citizens of other countries.  ! 

 Another point I should mention ,  is that it is preferable to have a daily dose of Vitamin D , rather than a weekly ,  or god forbid  a monthly dose. The reason for this is that the supplement VitD3 , is quickly converted , in the body ,  by a reaction in the liver ,   to   a substance called  calcidiol ,(25,OHD3), a blood storage form,   so within 3 days , your original  VitD3 is almost gone.   However ,   your cells do utilise  that VitD3, so you will have half a week  with  not much VitD3 available.     perhaps you could ask your doctor to give you a daily supplement. ?  , equivalent of what you are getting now. 

             The fact that your levels were as low as 11   in the past, indicates that either you are possibly  a low responder , or you might have some kind of absorption problem ,  or just  possibly you body may suppress your vitamin D level . This latter could be caused by  hyperparathyroidism.      No doubt your doctor has checked that that is not the case, and has measured your calcium level ?     Ask him, what it was ,   if it was normal ,  i.e below 2.5  mmol/L then at least you have eliminated that from any consideration.       IF  it has not been done ...  it would be prudent to do so.   

 Another reason for such a low level of 11 ,  might be that you completely avoid sources of vitamin D , i.e  sunshine on skin,   or  very heavy use of sunscreen, and/or combined with  a vegan /vegetarian diet, which has practically no VitD , unless specifically fortified.    Wild oily fish is one of the few significant natural food sources.  

  Whew ...   hope some of that was useful..!

Best of luck

BTBH.

PS If you need any more information , just get back to me.
.

BTBH thanks for that detailed response.

My thyroid is normal - 2.160 so within the 0.27 - 4.2 range, I have been eating oily fish a couple of times per week and approx 10 eggs per week from my own hens.

In the last 2 years my ferritin levels have gone up and are currently at 373 so well above the 13 - 150 ug/L range. I was tested to see if I've got hereditary haemochromatosis but I'm in the 10% of people with iron overload that's not heriditary. I had abdominal and pelvic ultrasounds nearly 18 months ago and they came back clear but my gp wants to do my bloods in 2 months time and if the ferritin level is still high she'll refer me for more ultrasounds as she said it's being deposited somewhere.

It's mostly tiredness and not so much aches in my bones that I suffer from. I've always kept in from the sun and would use sunscreen if I was going out in it but I'm trying to go out in it a bit more now.

My gp said I'll be on a maintenance dose for life - 700IU daily and she'll keep an eye on it.

I've just rechecked my vitamin D dosage, once the 8 weeks are up I've been prescribed to continue taking one 25,000 capsule per month. I'll ask my gp to change that when I go back for another blood test.

honey Good Plan ! Hope she agrees.

                 Also,   it is very important that you maintain a good blood level ,  that is why a repeat blood test is so important.   

          We see so many times , here on Mumsnet ,   that  a loading dose is given,  symptoms improve ,   then an inadequate maintenance dose is given ,   symptoms come back .       Then absolutely nothing is done with regards to  Vit D ,   the assumption is that treatment has been given , according to the prevailing guidelines ,   and so   the continuing problems are nothing to do with Vit D.  Nothing could be further from the truth.

    Sometimes repeat blood test are given, when the problems again become too severe to ignore , low VitD blood levels are found  ,    and the cycle repeats itself.   Don't get caught in that trap. 

 In order to  prevent this ,  we need adequate maintenance dosing ,    which  is DIFFERENT ,  for every one of us,   and very often much higher than the prevailing guidelines. As  you were down at 11,  this indicates your need is higher than just 700 IU  per day.     So,  IF  it was me,  I would check my level  , after loading dose , then after three months of maintenance, then after 6 months of maintenance... to see where it was going. Then establish my need for maintenance dose requirements.  IF you find your blood level of vitamin D continuously dropping ,  you need more. 

Prevailing NICE guidelines are based around the National Osteoporosis Soc guidelines, which are simply considering Vit D as a bone nutrient. It is not. It affects over 2000 of our genes, responsible for hundreds of bodily processes.

 I had better get off my soapbox now ...lol.  

Good luck from now on,

get back to me if you have any more questions

BTBH
.

Hi BTBH.
After I last wrote to you, I decided to take your advice and have my vitamin d level checked instead of experimenting with upping my dosage of vitamin d.
I told the doc I was getting symptoms again and he let me have it checked. Now it has come back as much better 79nmol/L! I don’t know what to make of this, as this doesn’t explain why i my legs and feet feel achy and sometimes stiff that I find it hard walking comfortably. Could my symptoms be down to something else? Could it be perimenopause? Or something else???

Also as I haven’t spoken to the doc since getting my results, I have no idea what I am meant to do with my vitamin d dosage. Do I carry on taking vitamin D? And if so, do I take it forever? And what dosage should i take? Should this dosage vary over the year or always be the same dosage? If I stop taking vitamin d tablets will my level fall back down to deficient? As from the leaflet the GP gave me it says my vitamin d level is acceptable so it’s not necessary to take vitamin d tablets.

Thanks in advance.

Mint you should go back to the doctor and say you still have the bone aching symptoms. It could be one of many things.

My hands and feet still ache/are numb in the mornings, and if my TSH levels rise(Thyroid test results) it is worse - pins and needles, numbness, tiredness.

When you say your thyroid levels are "fine" you might need to see what fine actually is. If you are at the top of the range, perhaps it isn't fine for you, individually. You need to know the actual level and perhaps get retested to see if the levels have increased over the last year, which would be a symptom of something amiss.

My TSH is now at 1.0. Normal in a blood test could be anything between 1 and 5 in our practice. But if I was 5 (TSH) it would set alarm bells ringing, it is way too high for me on thyroxine. I was diagnosed with Hashimotos when my TSH was 15..

But I'm not a GP, there are presumably other conditions that cause aches and debilitating tiredness.

Thanks Nettleskeins. Yes I think I need to go back to see the doctor.

hi again Mint ,
Yes , I can see it is a bit of a conundrum. However , applying Occam's Razor , ( the simplest explanation for any phenomenon should be preferred over more complicated explanations.. ! ) .
NOW , You have found that supplementing with 4000 IU per day , helped you , it reduced your symptoms. When you stopped that regime , and moved to a lower dose regime , the symptoms came back.

       I would have thought  that the obvious thing to do , would be to go back to 4000  IU  per day.   See if that helps.     IF  in 2 to three months time it hasn't helped ,   then take another course of action .   Don't stop Vitamin D supplementation ,   just because your level is 79nmol/L  .         As I have explained above in this thread,   imagine your body has compartments of vitamin D ,  which are continuously being filled , and continuously being emptied ,  as you use up your vitamin D .    Cells require vitamin D , day to day , to perform their normal natural functions.    If you are ill , or  have a trauma of some kind  for example ,   you will need  even more ,  as those cellular functions  need to be switched on ,  or cell behaviour needs to be modified.  Simply absorbing calcium from your food  will require a daily amount from your store of vitamin D. 
   See  my  bucket analogy up above in this thread. 

Of course ,  there may be other reason why you have your symptoms,  so as <strong>nettle</strong> says,    it might turn out that you have another problem,  such as  thyroid , maybe B12, maybe folate.  If you do look at these things , try to ensure you get a full investigation ,   i.e   not just a quick look at  TSH  ,   for thyroid.     The TSH  hormone  is not even a product of the thyroid gland ,  it is a pituitary hormone ,  you should look at   t4  t3 and  thyroid antibodies as well.   

   That pamphlet you have read , saying that 79  does not need supplement , is not looking at YOUR situation.   You have been on supplements ,  because your level was as low as 11 ,    therefore you needed treatment.         So,   now you are in the midst of treatment , and your level has been measured at 79 ,   it was   probably quite a bit higher when you were on 4000 IU, hopefully above 100 .   When you stopped 4000 IU ,  then your level probably dropped to 79 ,     and is now on its way down.    You must not look at any blood level as fixed , and never to change.  The key point is that you need , Vitamin D supplement ,  at the rate that your own metabolism requires.     It seems to be above 1500,     and probably just a bit below 4000 IU  per day.      
        In order to satisfy yourself that you are not overdosing ,   then I would suggest you get your calcium level measured  , in a couple of months.    Almost certainly ,  it will be normal.   IF  it is not ,    and  that's very unlikely ,   then you should consider what to do.       IF   and only IF ,  it is above normal,  then there is a chance you might have hyperparathyroidism.     The fact that your Vit D level was originally 11 ,   is likely to mean there is something about your lifestyle, or your genetics,or  your ability to absorb ,  or many other factors i.e smoking ?  etc ,   which might possibly hinder developing a satisfactory Vit D level. 
                  When you realise that , the human body  over millions of years , used to spend lots of time , outside , in strong sunlight , creating 10,000  to 20,000  IU  of vitamin D , per day   throughout our evolution (in Africa) ,    and it is only comparatively recently , that we have stopped that.   Then doses like 4000 IU   are not excessive. In fact as mentioned above  ,   the National Academy of Sciences , - Institute of Medicine ,  in the US ,  has said it is perfectly safe for a healthy adult to utilise that dose.    Modern day outdoor workers , lifeguards etc that  replicate those conditions ,   they have blood levels of vitamin D in the range 120 -140    and sometimes  quite a bit higher.     IF  you get to those levels ,    and stay there ,    then you are giving your body the chance to fight off , or repair , any problems that may have arisen due to low Vit D.        Make no mistake ,   a level of 11  was likely to cause all sorts of malfunction.  In children , it would be rickets and more. In adults, then bone pains , muscular weakness,  etc. immune system malfunction etc.
                                   In a way , you have been lucky ,   many people struggle with levels like 20 - 30 - 40  ,   for years and years,  not knowing ,   and just accepting the consequences ,  thinking it is just normal,  or old age ,  etc ....   You can do something about it.      It is only in the last few years that the true extent of Vit D insufficiency and deficiency has been realised ,   and  the effects on our bodies.  Scientific and medical research is progressing at quite a pace.  recommendations are slowly changing....    too slow  for my liking ...!

            Best of luck ,  

Get back to me if you have any more questions.

BTBH.

Hi again mint OOOPS
I apologize , for confusing your Vit D level , for honey's up above. Her level was originally 11 , your level was 30 , as you described in your earlier post. However your original level of 30 is still low , around the level a child might possibly have rickets, it is not a good level at all. All my comments still apply....
I do try to be as accurate as possible... sorry about that. Do try and keep your level above 100. It will benefit you enormously.

               BTBH.

.

Hi BTBH. Thank you for the detailed reply. Good to have all this information. When you say calcium level, do you mean checking the bone profile? As when they checked my vitamin d level, they also checked the bone profile which checks for Serum Calcium amongst other Serum ‘things’ and that all came back fine.
Also once one is vitamin D deficient, does one always have to supplement for life to make sure their level never falls back down to deficient?

I will take 4000IU daily and see what happens. I also have a doc appointment booked in for next month too, to discuss, in case of any other possibilities to my symptoms.

Hi again again mint ... !

Yes I meant serum calcium. The reason I mentioned , that you might like to check it after several months of significant supplementation , is for your own reassurance. You will feel more comfortable continuing with a dose of supplement , if you know for certain that it has no deleterious effects. By the way , hypercalcaemia , is the only known toxic effect of overdose of Vitamin D . It is incredibly rare, from that cause. If you have hyperparathyroidism , sarcoidosis , granulomatosis , Williams syndrome or carcinoma you should take it under medical supervision. The blood calcium check is a prudent thing to do. The fact that you had checks before you started is good, and the fact that you don't have hypercalcaemia prior to starting supplementation is great to know.

It is a common misconception that you are at risk of a higher blood level of calcium , if you take supplementation in the thousands of units.   Up to 10,000 IU  per day is perfectly reasonable ,  and will not result it toxic effects.   ( unless you have very rare diseases or conditions ) 

 Yes,       if you want to keep your levels of vitamin D , as I have been describing ,   then  it is most probable that you will have to supplement daily  for life.      Your environment ,  i.e. your normal daily food , and sunlight , in the UK,  cannot keep most of us at a "good" level. If you watch the video I posted up above ,   Prof. Veith ,   you will get a really good description of why that is the case.   You need a continuous , good level,  for optimal health,  not a highly variable level. That is why I say it is not a good thing to stop and start supplementation .  It is not a good thing to have big swings throughout the year. 

 Good Luck,    hope the docs appointment goes well. 

BTBH. 

.

@Bettertobehealthy can I ask you what dosage you'd recommend for a vitamin D level of 29.8 nmol/L please? Thank you!

Hi @PrettyFly0rAWifi

really you should be asking ,  " What blood level of vitamin D  should I achieve ,  and how should I dose myself in order to achieve it ?" 
                       The answer depends on several things, that are individual to your own body.  That is why you will see various ideas concerning how to supplement for different people.   We all respond differently to any particular  dose.

    1st consideration )  -  Dose type

Can you absorb supplements well ? , i.e if you have gut conditions or problems , they may hinder your absorption via the digestive system for example IBS, Crohn's , Coeliacs, IF you have any reason to suppose something hinders your absorption , then you might like to take an oral spray , rather than capsules or pills. An oral spray does not depend upon your digestive process , the Vit D goes straight into the bloodstream. Oral sprays are a bit more expensive than capsules. You can get them at 1000 IU or 3000 IU or 4000 IU per puff. They are quite easy to take, easy to remember, also with a pleasant taste. Gelatin capsules are the most common supplement, available in a great range of strengths. Solid pills are also available, they also will work. However, IF you have any reason to suppose you cannot digest fat or oils , i.e. gall bladder or bile problems , then you might not be able to easily absorb oil dissolved Vit D treatment. ( gel caps ). We are all different , by a factor of 6 to 1 , in our response to any particular dose, and how it is administered.

   2nd consideration )   -  Dose interval. 

                 Vitamin D exists as 3 active different compounds in your body.     When made in the skin by  UVB radiation ,  or taken as a supplement,  it starts out  as  VitD3, known as cholecalciferol.       After about 24 hours , your liver converts half of it to a compound called calcidiol, such that within 3 days ,  almost all of that  VitD3 (cholecalciferol) is converted to calcidiol. Technically - the half life is 24Hrs.  It is for this reason we need to dose daily or as close to daily as possible.  Weekly doses mean that for half the week or more ,  we don't have much VitD3 ( cholecalciferol) available to the cells that require it.   Cholecalciferol is used by  cells , whereby it is part of the machinery of gene transcription ( reading) , such that the cell converts cholecalciferol to calcidiol and then on to calcitriol, the hormone form of vitamin D, all within the cell.  At the same time as this is happening , the liver is busy converting some cholecalciferol to calcidiol as well..!  putting it into your blood serum.  IT  is this compound that is measured by your doctors test.  VitD3 ( cholecalciferol ) is NOT measured. It is the blood calcidiol only.    Calcidiol is used by some processes in the body ,  notably in the kidneys to make a further amount of calcitriol, the VitD hormone, used by the gut to regulate the absorption of nutrients etc.  From this explanation of your physiology – you should see that additional VitD3 should arrive in your body as close to daily as possible.  That is why Vitamin D researchers say that weekly or monthly doses are not as good as equivalent daily doses.  Every other day is not too bad. 


 3rd consideration  )  -  Dose Amount. 

              The amount you dose with , depends upon what you are trying to achieve.   Firstly you should realise , that it is the blood level that is important , and not the dose . We all vary in response by as much as a factor of 6 to 1 .  . We need to bring our blood levels up to a “good” level. Vitamin D researchers say that  100 – 150  , is a good level.     Here in the UK ,  very often you might be told  that  50 is an acceptable level.  Although that is slowly changing.    A minimum of 75  is  often recommended in some places.    You can expect your blood level to rise ,   by   25  nmol/L  ,  for daily supplementation of 1000  IU.  In the long term.   Lets say your original level was 30 ,   then  if you take an average of 4000  IU  per day , then you level should come up to around  120 – 130   after about  60 – 90 days. Remaining at that level , whilst you are taking that amount of supplement.  IF  you halve your  daily supplement to say 2000  IU ,  then you can expect your  blood level to drop by about  40 -50 .   These are all approximate values. As I explained before ,  we have different responses.   Those with a higher BMI , might  have less response.  Those with IBS , might have less response ,  particularly if they take capsules , and not oral spray.      In order to determine , what your response is ,   it is a good idea to measure your blood level, with a VitD test.   Your doctor can order it, or, you can get one done privately . A bloodspot on blotting paper , sent to a lab.  Here is an NHS Lab.  <a class="break-all" href="http://www.vitamindtest.org.uk/" rel="nofollow" target="_blank">www.vitamindtest.org.uk/</a>         Whatever your dose ,  once you have been  supplementing for  60 – 90  days  your blood level will stabilise.  So if you change your dose ,  wait  60 – 90 days ,  then test again. 

      You might be interested to know that 4000 IU   is said to be a  safe  daily dose for an adult by the IOM.( Institute of Medicine)  National Acadamy of Sciences  in the US.   A highly respected , conservative organisation , that sets National Guidelines for the US government. That we here in the UK , take a lot of medical influence from. 


For yourself ,   -  As someone that has a blood level of vitamin D at the end of summer ,   when it will be at maximum , from absorbed light ,  of just  29 ,   then I should be very interested in finding out what is going on, if I were you.    IF  you avoid almost all sunlight , use lots of suncreams,  and avoid any food with vitamin D in ,   eg  wild oily fish ,  if you are vegetarian ,  or vegan ,   then that might be a cause.  Alternatively - perhaps your body suppresses your vitamin D level.   That could be ,  I am NOT saying it is ,   BUT , that could be a sign of  hyperparathyroidism.  For that reason , I would advise that you get your calcium blood level checked at some point.    IF   it is not normal,   then your doctor should do something about it.     Don't heavily dose with vit D, in that instance.    It is a very unlikely situation ,   but it should be mentioned. 

Also, if you have sarcoidosis, granulomatosis , Williams syndrome , then take medical advice before treating yourself with Vitamin D. They are very rare conditions.

Assuming you have none of the above conditions , then a dose of 4000 IU per day would be eminently suitable. Followed by a blood test after roughly 3 months , say. IF you have a bit higher than average BMI , then 5000 IU should be just fine as well.

           Hope all that was helpful.  

            Best of Luck.

BTBH.
.

@Bettertobehealthy that is SO helpful - thank you for taking the time to write it for me. Lots to think about!

My level of 29 is probably due to my lifestyle! I do indeed avoid the sun - I work from home so don't go out during the day as such - and when I do, it's only to pop to the shops etc. I avoid sunbathing. I wear an SPF daily and I am a strict vegetarian with a somewhat poor diet (these results I've had recently have booted me up the backside though so I'm eating healthily now)

I had a raft of blood tests. My thyroid levels were optimal. I had a good HBA1C reading so no pre diabetes.

B12 and 9 just fine.

Iron low, globulin not great and my CRP was 13.2. I had these tests done privately and called my doctor in a panic who told me off and advised that the levels were all just a little off kilter and he wasn't concerned at all from a clinical point of view. He offered me blood tests in a month and said he expects the results to be absolutely fine as they were when I had them done 6 weeks ago (I only had private ones as I was curious about my vitamin D!)

I've bought some D and K tablets. 4000ui and been taking them for 3 days now so will see how I get on

Thank you again so much

@Bettertobehealthy I'm prettyflyforawifi with a new name!