I believe a testing level of 120ng/ml or greater is where you will begin to see vitamin D3 placing calcium in places undesired. Everyone is different in the amount of D3 needed. It is best to test. I personally try to keep a testing level between 60 to 70ng/ml. Haven't had problems when doing so.
An article along those lines.
"The folly of an RDA for vitamin D"
"Tom is a 50-year old, 198-lb white male. At the start, his 25-hydroxy vitamin D level was 28.8 ng/ml in July. Tom supplements vitamin D, 2000 units per day, in gelcap form. Six months later in January (winter), Tom?s 25-hydroxy vitamin D level: 67.4 ng/ml.
Jerry is another 50-year old white male with similar build and weight. Jerry?s starting summer 25-hydroxy vitamin D level: 26.4 ng/ml. Jerry takes 12,000 units vitamin D per day, also in gelcap form. In winter, six months later, Jerry?s 25-hydroxy vitamin D level: 63.2 ng/ml.
Two men, similar builds, similar body weight, both Caucasian, similar starting levels of 25-hydroxy vitamin D. Yet they have markedly different needs for vitamin D dose to achieve a similar level of 25-hydroxy vitamin D. Why?
It?s unlikely to be due to variation in vitamin D supplement preparations, since I monitor vitamin D levels at least every 6 months and, even with changes in preparations, dose needs remain fairly constant.
The differences in this situation are likely genetically-determined. To my knowledge, however, the precise means by which genetic variation accounts for it has not been worked out."