Deaths from severe megaloblastic anaemia in hospitalised patients

A 40-year-old woman 'off legs'

We present the case of a 40-year-old woman with progressive lower-limb weakness resulting in an inability to mobilise independently. This was associated with a degree of confusion and shortness of breath on exertion. This case illustrates rare and severe complications of vitamin B(12) deficiency, namely subacute combined degeneration of the spinal cord, megaloblastic anaemia and impaired cognitive function. The patient's condition improved considerably with adequate early resuscitation, followed by administration of synthetic vitamin B(12) analogues and neuro-rehabilitation.

How I treat cobalamin (vitamin B12) deficiency

The challenges in medical management of cobalamin deficiency lie in attention to the unique pathophysiology that underlies cobalamin deficiency, more than in the mechanics of therapy. The central physiologic principles are that clinically important deficiency is more likely to occur (and progress) when intrinsic factor-driven absorption fails than when diet is poor and that most causes take years to produce clinically obvious deficiency. Transient defects have little clinical impact. The key management principle is the importance of follow-up, which also requires knowing how the deficiency arose. The virtues of these principles are not always fully appreciated. Recent developments have made diagnosis and management more difficult by diminishing the ability to determine cobalamin absorption status. Clinicians must also grapple with premature medicalization of isolated, mild biochemical changes that added many asymptomatic cases of still undetermined medical relevance to their caseload, often expanded by inflated cobalamin level criteria. The potential for misattribution of cobalamin-unrelated presentations to nongermane cobalamin and metabolite abnormalities has grown. Pathophysiologically based management requires systematic attention to each of its individual components: correctly diagnosing cobalamin deficiency, reversing it, defining its underlying cause, preventing relapse, managing the underlying disorder and its complications, and educating the patient.

Acidosis and severe megaloblastic anaemia

Ten patients with severe megaloblastic anaemia were studied to investigate whether the causative metabolic defects might predispose them to lactic or other acidosis. One patient had compensated acidosis with hyperlactataemia before treatment but there were obvious causes other than anaemia. No other patient developed an acidosis. Neither anaemia per se nor the metabolic defects of vitamin B(12) or folic acid deficiency are likely to cause clinically significant lactic acidosis or hyperlactataemia.