MCV > 100 fl in all the following except
**Core Concept**
Normal MCV (Mean Corpuscular Volume) ranges from 80-100 fl. An MCV greater than 100 fl indicates macrocytosis, which can be caused by various factors such as vitamin B12 or folate deficiency, alcoholism, or myeloproliferative disorders.
**Why the Correct Answer is Right**
Macrocytosis is characterized by the production of abnormally large red blood cells. This is often due to impaired DNA synthesis, which can be caused by a deficiency in vitamin B12 or folate. Vitamin B12 plays a crucial role in the synthesis of DNA, and a deficiency can lead to a decrease in DNA synthesis, resulting in the production of larger than normal red blood cells. Similarly, myeloproliferative disorders such as polycythemia vera can also cause macrocytosis due to the increased production of red blood cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not provided, skipping to next option.
* **Option B:** Not provided, skipping to next option.
* **Option C:** Not provided, skipping to next option.
* **Option D:** This option is not provided in the question.
**Clinical Pearl / High-Yield Fact**
Remember that macrocytosis can be a sign of a underlying vitamin deficiency, and it's essential to investigate the cause of macrocytosis to prevent long-term complications.
**Correct Answer:**
Please provide the options so I can complete the explanation correctly.