My vitamin d level is at 80. i take 4000 units/day. my pcp says that 80 is too high and that i should cut back to 2000. your thoughts?

Vitamin D: If a little is good, a lot is not necessarily better. 80 ng/ml is either high, or high-normal, depending on the lab. Vit d toxicity can occur. Vit d is stored for some time in fat, liver. You could stop vit d entirely and your blood level would only come down slowly. Why not rely on quality nutrition, exercise (some outdoors) to maintain a healthy vit d?