A
B12 level of 159 is clearly low, and a month of Meganeuron OD+ is the usual way to correct it. Finishing the course doesn't automatically mean your level has normalised, since some people need a longer course depending on how low it was and what caused it.
Next Steps
Get a repeat
B12 test now that the course is done, so your doctor can see whether it's back in a healthy range or needs continuing. Add more B12-rich foods like eggs, dairy and meat if you eat non-veg, since diet is a common reason levels drop.
Health Tips
If you notice tingling in your hands or feet, memory lapses, or your fatigue hasn't improved, please consult your physician, since that can mean you need a longer course or a check for an absorption problem.