Vitamine B12 Deficiency Presenting As Severe Pancytopenia in Adult Patients. a Monocentric Study of 104 Cases

Vitamin B12 deficiency should be suspected in all patients with unexplained anemia and/or neuropsychiatric symptoms, and special attention should be paid to patients at risk (the elderly, vegetarians, patients with autoimmune thyroiditis or vitiligo, patients receiving proton pump inhibitors or biguanides for prolonged periods). Documented symptomatic pancytopenia related to cobalamin deficiency is very rare representing less than 5% cases in different series. We aim to report an important series of pancytopenia related to cobalamin deficiency to analyze the clinical, biological and outcomes of those patients.

Methods :

Consecutive patients presented with B12 deficiency and pancytopenia were included. Charts were retrospectively reviewed from an internal medicine department during a period of 15 years (2000-2015). Diagnosis of cobalamine deficiency used the vitamin B12 dosage bellow 200 pg/ml. Assessment included clinical features, blood count and morphological review and a statistical analysis of those parameters comparing pancytopenic and non-pancytopenic patients.

Results

The medical records of 268 consecutive patients hospitalized for cobalamin deficiency from January 2000 to December 2015 were identified and retrospectively analyzed. Among them, 104 patients had pancytopenia (38.8%). The median age was 55+17 years and the sex ratio : 1. Pancytopenia revealed vitamin B12 deficiency in all cases. Neurological manifestations were associated in 13 cases and digestive involvement in 16 cases. Twenty five patients presented with febrile neutropenia. Fourteen patients (13.4%) presented with "pseudo" thrombotic microangiopathy.

The mean hemoglobin level was 58+19 g/L, the neurtophils count was 1188+579/µl and median platelets count was 69.616+34.379/µl. Macrocytosis was present in 80.7% of patient with mean MCV was 106+11 fl, but was normal (<95 fl) in 20 patients. The mean serum vitamine B12 levels was 80+11 pg/ml. The median serum lactate dehydrogenase level was high (3.204 IU/L).

The causes of B12 vitamin deficiency were mainly food cobalamin malabsorption (63.4%) and pernicious anemia (28.8%). Correction of the hematological abnormalities was achieved in all patients treated with either intramuscular, subcutaneous or oral cyanocobalamin.

Significant differences appears comparing patients with or without pancytopenia. Pancytopenic patients had significantly lower MCV mean (p=0.001), lower polynuclear neutrophils count and lower platelets count. Atrophic gastritis was also significantly associated with pancytopenia (p=0.005). There was no significant difference in mean haemoglobin level (p=0.3), serum cobalamin level (p=0.17). Looking at other variables that could explain the high prevalence of pancytopenia in our series, there were no difference in ferritinemia level or number of patients with of iron deficiency .

Conclusion

In this study, based a single institution with a large number of consecutive patients with well-documented cobalamin deficiency, we found a high prevalence (38,8%) of severe pancytopenia. We don't find yet an explanation for those findings. Those results can also remind us that severe vitamin B12 deficiency may present with findings mimicking malign hematologic disorder and timely recognition and supplementation lead to resolution of symptoms and blood abnormalities.