PREVALENCE AND HEMATOPOIETIC EFFECTS OF LOW SERUM VITAMIN-B-12 LEVELSIN GERIATRIC MEDICAL PATIENTS

The clinical significance of low serum vitamin B-12 levels In elderly people is controversial. We aimed to document the prevalence of a low serum vitamin B-12 (< 175 pmol/l) in patients referred to a geriatric medical unit, and to determine whether haemopoiesis is commonly affect ed in elderly patients with low serum vitamin B-12. We studied prospec tively 472 consecutive referrals to a geriatric medical unit; fifty-si x (13 %) had a low serum vitamin B-12 level, of whom nineteen (34 %) o f the fifty-six also had evidence of Fe deficiency (serum ferritin < 4 5 ng/ml). Low vitamin B-12 was associated with a raised mean erythrocy te volume (MCV; mean 96.0 (SD 6.7) fl), compared with a control group (91.7 (SD 6.0) fl; P = 0.001). However, only thirteen (23 %) of the fi fty-six patients with a low vitamin B-12 had an MCV greater than or eq ual to 100 fl. Mean haemoglobin (Hb) levels were not significantly red uced in those with a low vitamin B-12. In a subsequent study the haema tological response to intramuscular hydroxocobalamin was examined in t hirty-four patients with a low serum vitamin B-12. Treatment resulted in a significant fall in MCV and rise in Hb; these effects could be de tected both in those patients with an initially normal full blood coun t (change in MCV -1.2 (SD 1.2); Hb + 0.5 (SD 0.6); p < 0.01) and in th ose with macrocytosis and/or anaemia (-9.1 (SD 11.8); + 0.8 (SD 1.2); P < 0.05), A low serum vitamin B-12 is common in geriatric medical pat ients. This is usually associated with an upset in erythropoiesis, alt hough the abnormalities are often subtle and may not be apparent on in spection of the full blood count, Elderly patients with serum vitamin B-12 < 175 pmol/l should be assumed to have vitamin deficiency even if their full blood count is normal.