Decline of serum cobalamin levels with increasing age among geriatric outpatients.

: The level of serum cobalamin declines with increasing age. Among 100 consecutive geriatric outpatients who were seen in office-based settings for various acute and chronic medical illnesses but not for cobalamin deficiency-related diseases, 11% had serum cobalamin levels from 148 to 295 pmol/L. The average annual serum cobalamin level decline was 18 pmol/L for patients who had higher initial serum cobalamin levels (actual range, from 224 to 292 pmol/L). The average annual serum cobalamin decline was 28 pmol/L, which was much higher, for patients who had lower initial serum cobalamin levels (actual range, from 157 to 221 pmol/L). Patients with initial serum cobalamin levels of 148 pmol/L or below received treatment immediately, and their declines could not be studied.