Absence of gastric intrinsic factor, which is normally produced by the parietal cells of the stomach, and is required for the absorption of vitamin B12.

Abnormal sensations such as tingling, pricking, or numbness of the skin with no apparent physical cause.

An abnormality of the primary sensation that is mediated by peripheral nerves (pain, temperature, touch, vibration, joint position). The word hypoesthesia (or hypesthesia) refers to a reduction in cutaneous sensation to a specific type of testing.

Anemia characterized by the presence of erythroblasts that are larger than normal (megaloblasts).

Larger than normal size of erythrocytes.

Red blood cell distribution width (RDW) is a simple parameter of the standard full blood count and a measure of heterogeneity in the size of circulating erythrocytes. It is provided by automated hematology analyzers and it reflects the range of the red cell size. It is calculated by dividing the standard deviation of erythrocyte volume by the mean corpuscular volume (MCV) and multiplied by 100 to convert to a percentage.

A laboratory test result indicating an abnormally high quantity of abnormal immature red blood cells with megaloblastic features.

The concentration of vitamin B12 in the blood circulation is below the lower limit of normal.

An elevated level of the enzyme lactate dehydrogenase in the blood circulation.

An abnormally low concentration of haptoglobin in the blood circulation. Decreased haptoglobin in conjunction with increased reticulocyte count and anemia may indicate hemolysis. Decreased haptoglobin levels can also occur in the absence of hemolysis, due to cirrhosis of the liver, disseminated ovarian carcinomatosis, pulmonary sarcoidosis, and elevated estrogen state.