1. If I have an elevated MMA, why might my doctor hesitate to diagnose me with vitamin B12 deficiency?
If your B12 test result is in the lower end of the normal range and you do not have significant symptoms, your doctor may feel that you have adequate B12 and will rely on these findings rather than on the elevated MMA. This may be especially true if your homocysteine level is normal. Your doctor may want to monitor your condition over time. He may be reluctant to start you on what could be lifelong treatment with B12 injections and/or oral supplementation unless he feels it is truly necessary.
2. Can either blood or urine be used for the MMA test?
In most cases, it is okay to use blood or urine for this test. Sometimes, your doctor may want to test both your blood and urine in order to compare the MMA results. Since homocysteine is a blood test, it may be more efficient to draw blood for both the MMA and homocysteine tests when they are ordered together.
