I backed down to 10,000 IU until I have another test for vitamin D next week. I alternated every two days for a while between 50,000 IU and 5,000 IU and for the past few days have stayed at 10,000. I will have the CBC test, CRP, vitamin D, 25 Hydroxy, vitamin B12, folate, fibrinogen, testosterone, TSH, Free T3, Free T4, and regular T4 blood tests. I believe DHEA too. It's my treat to myself each year during the LEF anual membership discount.