Carmel R
Department of Medicine, University of Southern California, School of Medicine 90033.
Arch Intern Med. 1988 Aug;148(8):1712-4. doi: 10.1001/archinte.148.8.1712.
When patients are examined for possible cobalamin deficiency, great stress is often placed on the presence or absence of macrocytosis and anemia and on how low the serum cobalamin level is. The present study, however, shows that only 45 (64%) of 70 consecutively diagnosed patients with pernicious anemia, the most common cause of cobalamin deficiency, had very low cobalamin levels (less than 74 pmol/L [or less than 100 ng/L]). Anemia was absent in 13 (19%) of the patients, and macrocytosis was absent in 23 (33%) of the patients; such absence was particularly common when cobalamin levels were only slightly or moderately low (74 to 184 pmol/L). Coexisting iron deficiency was responsible for the absence of macrocytosis in nine patients. Of the ten patients with neither anemia nor macrocytosis, neurological disturbance was prominent in six, including four whose only noticeable abnormality was cerebral. These observations indicate that macrocytosis and anemia, two classic features of pernicious anemia, may be overstressed in our diagnostic approach. All subnormal serum cobalamin results are best viewed as pathological until proved otherwise. Emphasis on only very low cobalamin levels risks delaying the diagnosis of pernicious anemia in a substantial proportion of cases, particularly in those without anemia or macrocytosis.
在对患者进行钴胺素缺乏可能性检查时，往往非常重视是否存在大细胞性贫血以及血清钴胺素水平有多低。然而，本研究表明，在70例连续诊断为恶性贫血（钴胺素缺乏最常见的原因）的患者中，只有45例（64%）的钴胺素水平极低（低于74 pmol/L[或低于100 ng/L]）。13例（19%）患者无贫血，23例（33%）患者无大细胞性贫血；当钴胺素水平仅轻度或中度降低（74至184 pmol/L）时，这种情况尤为常见。9例患者无大细胞性贫血是由于并存缺铁。在既无贫血也无大细胞性贫血的10例患者中，6例有明显的神经功能障碍，其中4例唯一明显的异常是脑部异常。这些观察结果表明，大细胞性贫血和贫血这两个恶性贫血的典型特征，在我们的诊断方法中可能被过度强调了。在未得到其他证明之前，所有低于正常的血清钴胺素结果最好都视为病理性的。仅关注极低的钴胺素水平可能会使相当一部分病例中恶性贫血的诊断延迟，尤其是在那些无贫血或大细胞性贫血的病例中。
