In the treatment of megaloblastic anemia, vitamin B12 and folic acid should be given together because
**Core Concept**
Megaloblastic anemia is a condition characterized by the production of abnormally large red blood cells that are unable to function properly. It is caused by a deficiency in either vitamin B12 or folic acid, which are essential for DNA synthesis and cell division.
**Why the Correct Answer is Right**
When vitamin B12 and folic acid are given together, it is essential to prevent the masking of vitamin B12 deficiency by folic acid. Folic acid can correct the megaloblastic anemia caused by a deficiency in folic acid, but it cannot correct the neurological damage caused by a deficiency in vitamin B12. If only folic acid is given to a patient with a vitamin B12 deficiency, the anemia will improve, but the patient will still develop neurological symptoms such as numbness and weakness in the legs. This is because vitamin B12 is necessary for the maintenance of the nervous system, and a deficiency in vitamin B12 can lead to demyelination of the nerves.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a valid reason for giving vitamin B12 and folic acid together.
**Option B:** This option is not a valid reason for giving vitamin B12 and folic acid together.
**Option D:** This option is not a valid reason for giving vitamin B12 and folic acid together.
**Clinical Pearl / High-Yield Fact**
It is essential to diagnose and treat vitamin B12 deficiency before giving folic acid to patients with megaloblastic anemia, as folic acid can mask the symptoms of vitamin B12 deficiency and lead to irreversible neurological damage.
**Correct Answer:** C. To prevent masking of vitamin B12 deficiency by folic acid.