 There is a blood test, and I know about it because I'm a medical nutritionist, that we do if we find someone as low as B12. First pass, you don't do that test. First pass, and it's pretty reasonable in people over 60 or people who have medical conditions or people who have other autoimmune conditions. You have autoimmune thyroid disease, you have celiac disease, yeah, check for B12 deficiency. That makes sense because these autoimmune diseases sometimes come in groups.