Troubleshooting anaemia in the elderly

Dear Sir,

Anaemia is a public health problem, especially in the elderly, being present in up to 20% of subjects aged 85 years and older. Given the prevalence of this pathology and the poor associated outcomes, a reliable diagnostic approach for troubleshooting the causes or the underlying disorders should be welcomed.

We are really grateful to Andrei and Mecili for their letter, which gives us the opportunity to debate this important issue further. We thought that our hypothesis was probably unclear or misinterpreted. We concluded that the cost-effectiveness of screening for nutritional deficiencies in older individuals is questionable, since the main cause of anaemia in this setting is renal failure so that widespread testing would be associated with substantial expenditure and limited diagnostic efficiency¹. As such, we wish to clarify and broaden some key concepts, with the aid of a tentative algorithm for reliable and cost-effective troubleshooting of anaemia in the elderly (Figure 1).

Figure 1.

Tentative algorithm for troubleshooting anaemia in the elderly.

The foremost problem is more theoretical than practical, and is related to the basic question: "What is anaemia"? It is universally accepted and supported by reliable sources (including the World Health Organization), that anaemia can only be diagnosed when the level of haemoglobin falls below 13.0 g/dL (13.2 g/dL according to Beutler) in men, or below 12.0 (12.2 g/dL) in women, irrespective of the presence of nutritional deficiencies^2,3. Accordingly, no further testing is necessary when the measured haemoglobin level is above these thresholds. Conversely, when the haemoglobin concentration is decreased, the first step should essentially be the evaluation of renal function by estimating the glomerular filtration rate using the traditional Modification of Diet in Renal Disease (MDRD) study formula⁴, or the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation⁵. According to our data, when the glomerular filtration rate is reduced the likelihood that impaired renal function is the main determinant of anaemia is so high that further testing is probably unnecessary. However, when the glomerular filtration rate is still maintained (e.g., >60 mL/min/1.73 m²), further testing should be guided by the value of the mean corpuscular volume (MCV), a simple an inexpensive parameter routinely measured in all clinical laboratories. As such, a decreased value of MCV in the elderly is highly suggestive of iron deficiency and should be followed by ferritin testing. On the other hand, an increased MCV is suggestive of other forms of nutritional deficiencies, so that it might be advisable to limit folate and vitamin B12 testing to this circumstance. Although this tentative algorithm has obviously been developed according to the results of our investigation, we hope that it might be helpful in other settings.