Hematologic abnormalities following gastric resection.Major Probl Clin Surg. 1976; 20:119-28.MP
The anemia observed in patients with partial gastric resection results from a complex interrelationship of deficiencies of these three important hematemics-iron, vitamin B12, and folic acid. Reliance upon morphological evidence of anemia in the peripheral blood smear may be difficult and confusing since deficiency of one hematemic may mask the coexisting deficiency of another. It is common for deficiencies of more than one hematemic to occur in these patients. A number of studies have demonstrated the masking effect of iron deficiency on concurrent vitamin B12 or folic acid deficiency. In addition, the morphologic hallmarks of iron deficiency may be modified by the presence of deficiencies of either vitamin B12 or folate or both. Full hematologic recovery may not occur until more than one hematemic is given to the patient. It is our policy at the University of Florida to rely on serum levels of these three hematemics, especially vitamin B12 and iron, to detect the cause of the anemia in a patient with partial gastric resection. Less reliance is placed upon the appearance of the peripheral smear because of the masking effect described above. If either the serum iron level or vitamin B12 level is decreased, we treat the patient with a preparation such as ferrous sulfate (300 mg. orally three times a day) and vitamin B12 (100 mug. intramuscularly once a month). We are less concerned with folic acid deficiency because of its relatively infrequent occurrence in this setting and because a good diet will usually suffice as adequate therapy for the folic acid deficiency when present. In patients who have had partial gastric resection but who are not anemic, we assess vitamin B12 absorption by the conventional vitamin B12 urinary excretion test (Schilling test) on a yearly basis since deficiency of this hematemic may lead to serious hematologic and neurologic sequelae. If the patient manifests decreased vitamin B12 absorption uncorrected by the administration of pancreatic extract or antibiotics, this patient is also treated with 100 mug. of vitamin B12 intramuscularly on a monthly basis. We have not evaluated the absorption of food B12 as suggested by Doscherholmen. Perhaps more attention should be paid to this aspect of vitamin B12 absorption in these patients. Indeed, because of the serious complications of vitamin B12 deficiency and the observations that deficiencies of this vitamin may occur even when the absorption of crystalline vitamin B12 is normal in the fasting state (the conventional Schilling test), some authors, such as Rygvold, have suggested that prophylactic vitamin B12 be administered to all patients with partial gastric resection.