Hi doctor. Thank you for reading and responding to this. Today morning while taking my blood samples for Vitamjn D and B12 test the Phlebotomist said my blood is very thick. He said it's not a good sign and I should go for additional test to identify the problem. It did take a while for the tube to fill up with blood. Should I be worried and go for further tests? I was diagnosed with covid last year and didn't require hospitalisation. I am non diabetic. My Cholesterol level has always been on the border Please suggest. Thank you