[donocco]

I found something intersting. Low calcium intake is one cause of low levels. If the calcium levels fall the body secretes parathyroid hormone and this hormone changes 25-Hydroxy Vitamin D (what is measured) to the more active Vitamin D form calcitriol. The body makes calcitriol from the 25 hydroxy form so the measured Vitamin D levels drop. Maybe you can increase your calcium intake. Also take the Vitamin D with some fatty food ie in the evening before dinner. Too high a blood calcium also drops the 25 Hydroxy Vitamin D levels due to the thyroid release of a hormone called Calcitonin, so it works both ways.