Question 1

It is much easier to become folate-deficient than B₁₂-deficient because:

Accepted Answer

The body stores vitamin B₁₂ in larger quantities and can maintain these stores for several years, whereas folate stores are smaller and can be depleted more quickly, leading to deficiency.

Question 2

Macrocytes are often seen in hospitalized alcoholics due to:

Accepted Answer

Macrocytes are a hallmark finding in alcoholics due to the toxic effects of alcohol on erythroid precursors in the bone marrow. This leads to impaired DNA synthesis and delayed maturation of red blood cells, resulting in larger than normal cells.

Question 3

Which of the following is found in megaloblastic macrocytosis and not in nonmegaloblastic macrocytosis?

Accepted Answer

Megaloblastic macrocytosis is typically associated with both decreased vitamin B₁₂ levels and decreased WBC count, which are not typically seen in nonmegaloblastic macrocytosis. Additionally, patients with megaloblastic macrocytosis may have normal-to-decreased reticulocyte counts, while serum bilirubin levels are not typically affected by macrocytosis.

Question 4

Patients with blind loop syndrome can have vitamin B₁₂ deficiency complications due to:

Accepted Answer

The answer of Patients with blind loop syndrome can have...

Question 5

Neurological symptoms are prevalent in Vitamin B₁₂ deficiency because of:

Accepted Answer

The answer of Neurological symptoms are prevalent in Vitamin B₁₂...

Question 6

Vitamin B₁₂ is a cofactor used in the conversion of _______ to _______.

Accepted Answer

Vitamin B₁₂ acts as a cofactor in the conversion of 5-methyltetrahydrofolate to tetrahydrofolate by the enzyme methionine synthase.

Question 7

Deficiencies in folic acid lead to which of the following?

Accepted Answer

The answer of Deficiencies in folic acid lead to which...

Question 8

The nuclear cytoplasmic asynchronous morphology in megaloblastosis is best characterized by:

Accepted Answer

Megaloblastosis is characterized by nuclear immaturity with cytoplasmic maturity, a hallmark of defective DNA synthesis, often due to vitamin B12 or folate deficiency.

Question 9

Which test is a better indicator of folate status in the body over the last month?

Accepted Answer

RBC folate level is a better indicator of folate status over the last month as it reflects the amount of folate stored in the body's tissues, whereas serum folate levels can fluctuate rapidly in response to recent dietary intake. Vitamin B₁₂ level and MMA are not direct measures of folate status.

Question 10

Use this case to answer the following questions. A 55-year-old male consulted his physician because of weakness, lightheadedness, vertigo, and angina. The patient also complained of sores on his tongue. The physical examination revealed jaundice. The pulse rate was increased, and the spleen and liver were slightly enlarged. The tongue appeared smooth and bright red in color. Family history revealed no clues. Neurological exam revealed quickening of reflex responses. Patient history indicated a total gastrectomy five years ago for stomach cancer and intermittent heart problems that had not required surgery. The physician ordered the following tests:
 $\begin{array}{ll}
\text { TEST } & \text { RESULTS } \
\text { WBC } & 3.1 \times 10^{9} / \mathrm{L} \
\text { RBC } & 2.45 \times 10^{12} / \mathrm{L} \
\text { HGB } & 10.5 \mathrm{gm} / \mathrm{dL} \
\text { HCT } & 29.0 \% \
\text { MCV } & 118 \mathrm{fl} \
\text { MCH } & 42.8 \mathrm{pg} \
\text { MCHC } & 36.2 \mathrm{gm} / \mathrm{dL} \
\text { RDW } & 15.7 \
\text { PLT } & 83 \times 10^{9} / \mathrm{L}\
\text { Differential: }\
\text { Polys } & 49 \% \
\text { Stabs } & 6 \% \
\text { Lymphs } & 30 \% \
\text { Mono } & 8 \% \
\text { Eos } & 5 \% \
\text { Basos } & 2 \%
\end{array}$ 
Peripheral blood: macro-ovalocytes, no hypersegmentation noted.
-What is (are) the most appropriate reflex test(s)?

Accepted Answer

The macrocytic, normochromic anemia, the presence of jaundice, and the sores on the tongue suggest megaloblastic anemia. The patient's history of total gastrectomy five years ago for stomach cancer puts him at risk for pernicious anemia. Testing for vitamin B₁₂ and folate levels is essential to determine the cause of the anemia. Iron studies and hemoglobin electrophoresis would not be necessary in this case, as they would not explain the patient's symptoms. Bilirubin levels would help support the diagnosis of hemolytic anemia, but they would not be helpful in determining whether the anemia is megaloblastic or macrocytic.

Question 11

What can falsely elevate the serum folate level?

Accepted Answer

Hemolysis of the serum sample can release intracellular folate and falsely elevate the serum folate level. It is important to ensure the serum sample is not hemolyzed when measuring folate levels.

Question 12

Which clinical manifestation is common in vitamin B₁₂ deficiency but not in folate deficiency?

Accepted Answer

The answer of Which clinical manifestation is common in vitamin...

Question 13

Pernicious anemia is a disorder characterized by:

Accepted Answer

Pernicious anemia is caused by a lack of intrinsic factor (IF), a protein that helps the body absorb vitamin B12 from the gastrointestinal tract. Without sufficient IF, the body cannot absorb enough vitamin B12, leading to a deficiency that can cause anemia and other neurological symptoms. While anti-vitamin B12 antibodies may be present in some cases of pernicious anemia, they are not the underlying cause. Improper dietary intake of vitamin B12 can also lead to a deficiency, but this is not specific to pernicious anemia. Increased absorption of vitamin B12 would actually alleviate the symptoms of pernicious anemia, not cause them.

Question 14

Pernicious anemia is a malabsorption of vitamin B₁₂ due to what component deficiency?

Accepted Answer

Pernicious anemia is a condition where the body is unable to absorb vitamin B₁₂ properly. This is due to a lack of intrinsic factor, a protein made by cells in the stomach, which is necessary for the absorption of vitamin B₁₂ in the small intestine. Gastric juice, histamine, and folate are not directly involved in the absorption of vitamin B₁₂.

Question 15

A blood specimen is analyzed.The MCV is increased, the hemoglobin level is decreased, and the reticulocyte count is normal or low.What test could give more information on the cause of the anemia without drawing another blood specimen?

Accepted Answer

A blood smear morphological exam would allow for visualization of the red blood cells and potential abnormalities such as size, shape, and appearance. This could provide more information on the specific type of anemia and potential underlying causes. The other options (serum iron, vitamin B12 assay, serum alcohol) would not provide information specific to the type of anemia.

Question 16

The reason that lack of vitamin B₁₂ causes megaloblastic changes is because vitamin B₁₂:

Accepted Answer

Vitamin B₁₂ is necessary for the production of nucleotide bases, which are the building blocks of DNA. Without sufficient vitamin B₁₂, there is a decreased production of DNA, which leads to megaloblastic changes in the bone marrow.

Question 17

Predict the levels of MMA and homocysteine in patients with Vitamin B₁₂ deficiency.

Accepted Answer

The answer of Predict the levels of MMA and homocysteine...

Question 18

Megaloblastic anemia is most often caused by deficiencies of what two components?

Accepted Answer

Megaloblastic anemia is most often caused by deficiencies of vitamin B₁₂ and folate. These two components are necessary for proper DNA synthesis and cell division in red blood cell production. Without adequate levels of these vitamins, red blood cells are unable to divide properly and become larger than normal, leading to megaloblastic anemia. Iron deficiency anemia, on the other hand, is caused by a lack of iron in the body, which is necessary for the production of hemoglobin, the protein that carries oxygen in the blood. Liver disease can also cause anemia but is not directly related to megaloblastic anemia.

Question 19

All of the following disorders can lead to macrocytic anemia except:

Accepted Answer

Macrocytic anemia is typically caused by deficiencies in vitamin B12 or folate, or by various medical conditions such as alcoholism or liver disease, but not by iron deficiency. Iron deficiency can lead to microcytic anemia instead. Hypothyroidism may cause a mild macrocytic anemia due to alterations in the erythrocyte membrane lipids, but it is not a common cause of macrocytic anemia.

Question 20

Megaloblastic anemia is characterized by:

Accepted Answer

Megaloblastic anemia is characterized by hypersegmentation of PMNs, or neutrophils with more than 5 lobes in the nucleus. The other choices are not typically seen in megaloblastic anemia. Heinz bodies are seen in hemolytic anemias, hypochromia is seen in iron-deficiency anemia, and microcytosis is seen in thalassemias and iron-deficiency anemia.

Quiz 12: Megaloblastic and Nonmegaloblastic Macrocytic Anemias