Table 2. Severe and mild categories of B... | American Society of Hematology

Table 2.

Severe and mild categories of B₁₂ deficiency

	Severe	Mild
Mechanism	Disruption of intrinsic factor/cubam absorption	Failure of gastric digestion and release of food B₁₂
Enterohepatic reabsorption of biliary B₁₂	Interdicted	Intact
Manifestations	Megaloblastic anemia and/or neurological complications	Megaloblastic anemia and serious neurological deficits rare; associated with more rapid cognitive decline
Rate of depletion	Rapid, and may be extreme	Slow, usually mild and usually limited
Treatment	Require lifelong regular B₁₂ replacement, either monthly injection or daily high-dose oral B₁₂	Responds to daily physiological dose supplements of oral B₁₂

	Severe	Mild
Mechanism	Disruption of intrinsic factor/cubam absorption	Failure of gastric digestion and release of food B₁₂
Enterohepatic reabsorption of biliary B₁₂	Interdicted	Intact
Manifestations	Megaloblastic anemia and/or neurological complications	Megaloblastic anemia and serious neurological deficits rare; associated with more rapid cognitive decline
Rate of depletion	Rapid, and may be extreme	Slow, usually mild and usually limited
Treatment	Require lifelong regular B₁₂ replacement, either monthly injection or daily high-dose oral B₁₂	Responds to daily physiological dose supplements of oral B₁₂