VITAMIN-B-12 DEFICIENCY - EARLY DIAGNOSIS IN THE AMBULATORY SETTING

Many patients suffer from vitamin B-12 deficiency and are thus exposed to irreversible sequelae if diagnosis occurs at a late stage. This pr ospective study undertaken by eight practitioners over a period of 12 months concerns early diagnosis. Blood vitamin B-12 levels were measur ed in 152 patients presenting macrocytosis detected by systematic MCV analysis at the time of a blood test, a neuropathy or a recent cogniti ve, affective and behavioural problem, and were found to be lowered (l ess than or equal to 175 pmol/l) in 54 patients of whom 43 had undergo ne vitamin B12 test treatment for 6 months. Haematological, neurologic al and psychiatric evaluation was carried out before and after treatme nt, and a diagnosis of deficiency was recorded in 24 patients based on unequivocal response to therapy. Improvement was greatest haematologi cally in 12 patients, neurologically in 6 patients and psychiatrically in 6 other patients, with 4 patients showing a combination of all mod es. These 24 patients (mean age 69 years) suffered from numerous patho logies which were liable to complicate diagnosis in some of them: neur ological (46%), psychiatric (37%), chronic alcoholism (33%), folic aci d deficiency (29%), and diabetes (17%). The only diagnostic element us ed as a criterion of deficiency was an extremely low level of vitamin B-12 (less than or equal to 75 pmol/l). Marked macrocytosis or a combi nation of haematological and neuropsychiatric signs are strong indicat ors, but only improvement under treatment allowed a diagnosis to be ma de in the majority of patients. Macrocytosis was, however, not present in 6 of the 12 neuropsychiatric patients. The study thus identified a high proportion of patients with vitamin B-12 deficiency who addition ally presented, in equal proportions, both haematological and neuropsy chiatric symptoms. Neither the clinical examination nor the vitamin B- 12 level in general permit early diagnosis based on a high probability index and long-term follow-up. Simpler methods for early diagnosis ar e therefore needed.