My Dr has refered me to St. Thomas's hostpital London for a Venous Blood Specimen. I was self injecting once a week but she told me to stop injecting for one month. Will this test give an accurate reading of my B12 levels. I've not taken a B12 jab for 16 days and my old symptoms have returned. I don't know if the test is 100% true and if it's worth suffering without my B12 Jab. I also have MS, any info will be greatly appreciated. Thank you.