There has been an increase in overall hypervitaminosis D cases in the past few years, linked to either Vitamin D supplements or tanning bed use. Generally people can't get too much Vitamin D from foods and exposure to the sun. The recommended daily value of Vitamin D is also safe, sometimes people take multivitamin and a seperate supplement of calcium and Vitamin D, the intake adds up more than the recommended daily value, then high blood Vitamin D level occurs.
Some prescription can raise Vitamin D level, including thiazide diuretics, digoxin, and estrogen therapy.
Excessive Vitamin D in the body finally leads to too much calcium, and further leads to kidney stones, kidney damage and failure, excess bone loss, artery calcification.