Why might ldh be elevated in B12 deficiency?

RBC breakdown. Ldh enzyme (subtype 4h) is very abundant in red blood cells and heart muscle. In vit B12 deficiency there is high destruction of red cells in the bone marrow and in the blood vessels. As rbcs ruptures they release their inner content into the blood stream and this causing elevation of ldh levels in the bloodstream.
Non-specific. Elevation of ldh occurs in many conditions and is non-specific. Red blood cells are little packages stuffed with ldh. Anything that interferes with the integrity of red blood cells (like B12 def) may cause them to leak some of their cargo.