Certified Neuroscience Registered Nurse (CNRN) Practice Exam

A person with megaloblastic anemia due to vitamin B12 deficiency is likely to have which of the following?

1. High serum iron levels

2. Low serum vitamin B6 levels

3. High homocysteine levels

4. High platelet counts

The correct answer is: High homocysteine levels

Megaloblastic anemia, particularly that caused by vitamin B12 deficiency, is characterized by abnormalities in the synthesis of DNA during red blood cell formation. One of the notable biochemical changes in this condition is the elevation of homocysteine levels. Vitamin B12 plays a crucial role in the conversion of homocysteine to methionine; thus, when there is a deficiency, this conversion is impaired, leading to an accumulation of homocysteine in the bloodstream. The presence of high homocysteine levels serves as a marker for vitamin B12 deficiency and can contribute to various health issues, including cardiovascular diseases, due to its association with endothelial dysfunction. This highlights the importance of monitoring homocysteine levels in patients diagnosed with megaloblastic anemia to assess the severity of the deficiency and to guide treatment strategies effectively. In contrast, high serum iron levels, low serum vitamin B6 levels, and high platelet counts do not directly correlate with the specific pathophysiology of megaloblastic anemia due to vitamin B12 deficiency. Iron levels may be normal or low, vitamin B6 levels are typically not a focus in this specific type of anemia, and platelet counts are generally not elevated in these cases but may present with varying levels