Pernicious Anemia
A decrease in red blood cells when the body can't absorb enough vitamin B12. It is an organ specific auto immune diseases in which the body's immune system attacks the lining of the stomach.It was considered as a deadly disease due to the lack of available treatment. Pernicious anemia is most common in caucasian persons of north European ancestry than in other racial groups.
Vitamin B12
Vitamin B12 is a water-solu ble vitamin that keeps your nerves
and red blood cells healthy. It is responsible for the smooth
functioning of several critical body processes.
It helps to form red blood cells.
It is found in animal foods including meat, fish, eggs, milk and
other dairy products.
Causes
Intrinsic factor(IF) is a glycoprotein made in the stomach that is necessary for the absorption of vit812.
When the stomach does not make enough IF, the intestine cannot properly absorb vitamin B12.
As a result it can cause permanent damage to nerves and other organs.
Also parietal cells located within the gastric mucosa are destroyed.
It also raises risk for developing stomach cancer
Macrocytes
Without enough vitamin B12,the body will produce abnormally large red blood cells called macrocytes.
Due to their large size they do not leave bone marrow.
Gradually it decreases the amount of oxygen carried red blood cells in the blood stream and leads to fatigue and weakness.
So this is also called Macrocytic Anemia/Megaloblastic Anemia.
Very rarely it is passed th rough families. This is called Congenital pernicious Anemia.
Babies with this type of anemia do not make enough intrinsic factor.
Diagnosis
Test that may done include:
(1)Bone marrow examination
(2)Complete blood count (CBC)
(3) Reticulocyte count
(4)Schilling test
(5)LDH level
(6)Methylmalonic acid level(MMA)
TREATMENT 
•The goal of the treatment is to increse your vitamin B12 level
Eating foods high in vitamin B12 and folic acid can help to prevent vitamin B12 deficiency caused by a poor diet.
Some people may also need to take vitaminB12 supplement by mouth.
Certain type of vitB12 may be given through the nose.
