Vit. d has been between 20.0 and 20.9 for the last 4 years. daily vitamins and additional vit d supplement and numbers still 20.9 3 months ago. ?

Take more: If you take enough Vit D, your level will increase. Many people need a lot more than the recommended amount. You don't say how much you are taking, but you should take between 2000 and 5000 IU daily of Vit D3.

Vit D: If your practitioner is measuring serum Vit D, and not 25-OH D3 or 1,25-OH2 D3, then these values are low. Better is above 35 and best is 45-60. Your intake must still be low. Aim for 1000-2000 IU per day.

Vitamin D optimized: All sorts of different ideas on what's good, what's better, what's best...But I agree with Dr. Mahnesmith in terms of the higher range. As a neurologist my tendency in my neurological patients is to shoot for the 60-80 range. To that end I recommend a 2000IU gelcap to most and I don't really check levels or replenishment status for at least a good 8-10 weeks after initial boosts.