Pernicious Anaemia with Normal Vitamin B12

Abstract

A 49-year-old female patient presented to our hospital with asthenia, odynophagia, low grade fever, worsening symptoms of chronic depression, and symmetric leg paresthesias. Investigations showed macrocytic anaemia, leucopenia, thrombocytopenia, high lactate dehydrogenase levels and a normal Coombs test. Trilineage dysplasia was detected in the bone marrow biopsy specimen. The diagnostic work-up led us to the diagnosis of pernicious anaemia with a spuriously normal value of vitamin B12 and high titres of anti-intrinsic factor autoantibodies. This case highlights the importance of considering vitamin B12 deficiency in the differential diagnosis of myelodysplasia, even when vitamin B12 levels seem to be normal.

Challenges in the diagnosis of hypervitaminemia B12. Interference by immunocomplexes

“…Moreover, vitamin B12 has also been postulated as a useful biomarker of severity (prognosis) and death in such diseases [5][6][7], as well as, increased vitamin B12 concentrations might paradoxically be masking a deficiency [8]. This functional deficiency is associated with alterations in the uptake and tissue processing of cobalamin, or with the presence of antibodymediated analytical interferences such as macrocomplexes of vitamin B12 [macroB12, generally with immunoglobulins (immunocomplexes)] [9][10][11][12]. The presence of macrocomplexes is also a cause of hB12 little known by clinicians [13].…”