I am seeing people report some alarming things on the forum.
With regard to vitamin D and calcium levels, we all should know that the chief purpose of vitamin D is to cause absorption of calcium to make bones strong.
OK so far???
There are two forms of vitamin D both measurable in blood . The first called 25D is the store form and the other called 1,25D is the active form.
Both these forms of D are made to help us absorb calcium from food, but the active form of D can also make us resorb calcium from bone.
Calcium and D form a balancing feedback circuit in the body. When calcium is becoming high, we make less D; and when calcium is becoming low we make more D.
In health, Ds and calcium are well within normal range.
Sarcoidosis is a disease known that causes disturbance to the balance of vitamin D and calcium.
It does this by depleting store forms of vitamin D (normal or 25D), abnormally raising active forms of vitamin D (1,25D), and pushing up levels of calcium.
If however, you have osteoporosis or vitamin D deficiency you need more D in order to absorb more calcium. Therefore, in a bid to keep active D (1,25 D) at a normal level, and in order to absorb more calcium, ordinary or store D (25D) is depleted.
The mechanisms are completely different. If you do 25D tests alone, in both deficiency and sarcoidosis these levels are low. However, they are low due to polar opposite reasons.
The 1,25D or active form of D (which is rarely tested and only ever abnormal in disease states like sarcoidosis) is fairly often abnormally high in sarcoidosis. It will NEVER BE HIGH if you are in a vitamin D deficient state. It will be low or normal if you are D deficient, but if you have active sarcoidosis and are not currently on sarcoid meds, your 1,25D could be high.
Another test that can help differentiate D deficiency from sarcoidosis is the parathyroid hormone level or PTH. PTH helps to balance calcium in the body which is absorbed in the presence of vitamin D (1,25 D and not 25D). When calcium levels are high, less parathyroid hormone is triggered. When calcium levels are low, more parathyroid is triggered in order to synthesise more D.
Therefore, another means of finding whether your 25D is low because of deficiency is by doing a parathyroid hormone level.
If you are D deficient, the PTH or parathyroid level will be high or at least at the upper end of normal.
However, if you have active sarcoidosis and a high 1,25D level, your PTH will be low, signalling that you have a calcium level which is getting high and stopping D production. Your D is low because you have too much calcium.
So if you have sarcoidosis, and your doctor refuses to do 1,25D or PTH levels, try to find out what your calcium level is.
If your doctor announces to you that your 25D level is 13 and you need to go on D supplements ask them what your calcium level is.
If your calcium level is 4, then it will be reasonably safe to go on D. However, even if your calcium level is within normal limits, if it is toward the upper end of normal range then it is highly likely your sarcoidosis is not under control.
If your doctor tells you your D is 6 and your calcium is normal but 9 or 10 (Upper end of range is about 10.5) then you are highly unlikely to be deficient in D. Remember, we need D to absorb calcium. If calcium is the upper end of normal with a low D, you are not D deficient and do not need supplements. Taking supplements could push calcium out of range within a few weeks.
Here is another tip. Look at your CBC. 1,25 D affects the way sarcoidosis patients make blood cells and what these cells do. If you have a high 1,25D level with sarcoidosis, certain blood cells come out of circulating peripheral blood to form granulomas. This is reflected in the blood count, particularly of people who have CHRONIC sarcoidosis.
Look at your lymphocyte count which is in the differential CBC. If you have an abnormally low lymphocyte count, or low % lymphocytes in your count. It is increasingly likely that you will also have a high 1,25D level, which means that your 25D is low due to highish blood calcium levels, rather than low blood calcium levels.
highish calcium level
Vitamin D deficiency
lowish or normal 1,25D
If you have a highish calcium with a low D level it is probably due to sarcoid. Taking D will drive 25D lower and calcium higher. This is dangerous.
If you have a low D due to deficiency, you should expect a calcium on the other side of 5.
Please be careful. I have seen doctors tell patients they were D deficient when their calciums have only just been in normal range. You cannot have such a high calcium and be D deficient. Question your doctor if your calcium is at the upper end of normal when your 25D is low.