Lecture 3: Macrocytic and Megaloblastic Anaemias Flashcards
What are the haematinics?
It is away of broadly referring to vitamin B12 and folate. (sometime B12 and folate are paired together with ferritin.
What is the purpose of the haematinics?
They are intrinsic to the production of DNA within growing and dividing cells.
What are the reference ranges for folate and B12 in serum?
2.4-17.5 ug/L - Folate
200-800 ng/L - B12
What is vitamin B12?
Part of a chemical family known as cobalamins.
The structure that holds a cobalt atom in the in the middle is called the corrin ring or corrin nucleus.
How many metabolic pathways is B12 used for in humans? What are they?
There are 2 pathways.
1. Conversion of L-methylmalonyl coenzyme A to succinyl coenzyme A.
2. Methylation of homocysteine to methionine.
Where does vitamin B12 come from?
Vitamin B12 is only available through dietary consumption.
Animal products are greatest source
How much vitamin B12 is in a typical UK diet?
How much B12 is lost?
What is the average human store of B12?
How and where is vitamin B absorbed?
B12 is absorbed in the terminal ileum in an active process.
1. B12 forms
How is B12 transported?
What are folates?
The folates are a generalised name for a chemical belonging to the folic acid family.
Folate consists of several related chemicals such as tetrahydrofolic acid (active form), methyltetrahydrofolate (primary form in blood).
What does folate do in the body?
Folate acts as a single carbon donor/acceptor in a variety of reaction.
- Synthesis of methionine
- Histidine catabolism
- Converts serine to glycine
- Purine synthesis
- Pyrimidine synthesis
dUMP to dTMP
How is folate obtained in the body?
Must be absorbed from the diet.
Folate is absorbed in the upper jejunum.
What is the role of vitamin B12 and folate in DNA synthesis.
What do the terms macrocytic vs megaloblastic mean?
How do vitamin B12 deficiencies affect sufferers?
