I take 2000 IU a day of Vit D 3 by orders of my Endocrinologist. I have hyperparathyroidism and had 2 of my parathyroids removed. 1000 iu a day minimum is what all women should take. 2000 iu a day is safe.
Vitamin D absolutely does store in your body, it is a far soluable vitamin, not water. I personally have overdosed on just over 2000IU/day. It caused horrendous neurological problems. I am still off all calcium and D by mouth which has been 4 months,. I am slowly getting better but I know it would have killed me. Calciferol is D3 as well as the ingredient in rat poison.
The calcium level in urine is very important here and also the measure of phosphatemia and phosphaturia (in urine). Vit D must be activated to work (skin, liver and kidney), so it's important to measure both forms of Vit D to see what is going on. If you have bone decalcification, need to do X-ray. There are many possibilities, so test Ca levels (urine and serum, PO4, Alkaline phosphatase, and 25- (OH) D3 levels. As been said it is time to go to an ENDO.
What is the dosage of the Vit D you take? Why once a week? Vit D is lost on a daily basis. One of the few vitamins our body doesn't store. Did they do a blood calcium test or a urine calcium test? Calcium in the blood is all well and good as it shows you have calcium, BUT if you have a high level of calcium in the urine that means your Vit D is not doing its job, and is sending it bye-bye.
Yes, see an endocrinologist. Too many doctors have too little knowledge in this field.
I am having severe low calcium (rather than high) and low Vit D issues (even after taking supplements) so I know where your concerns come from!
I think you should go to an endocrinologist, and repeat the analyses of PTH and Vitamin D-25 (active) and Vit-D-1-25 (inactive form). You are right about Vit D,Vitamin D increases the amount of calcium in our body and usually higher calcium levels tend to have lower Vitamin D levels. Must look for your parathyroid.