Determinants of anaemia in the very elderly: a major contribution from impaired renal function?

BACKGROUND: Anaemia in the very elderly is usually dissected to a variety of root causes. The frequency of nutritional anaemias is particularly uncertain, since there is controversy on the real prevalence of folate, vitamin B12 and iron deficiencies, as well as on their potential pathophysiological relationship with anaemia. MATERIALS AND METHODS: We retrospectively analysed results of haemoglobin, ferritin, folate and vitamin B12 measurements performed on a cohort of unselected subjects over 85 years old who were referred by general practitioners for routine diagnostic check-up to our laboratory over the past 2 years. Furthermore, glomerular filtration rate (GFR) was estimated using the Modification of Diet in Renal Disease (MDRD) formula. RESULTS: The overall prevalence of nutritional deficiencies was low in males (<25%) and very low in females (<15%). Significant differences between anaemic and non-anaemic subjects were observed only for GFR in both males (44+/-3 versus 67+/-3 mL/min/1.73 m(2); p=0.035) and females (42+/-3 versus 61+/-3 mL/min/1.73 m(2); p=0.019). Likewise, a significantly difference in the frequency of anaemic and non-anaemic subjects with values below the conventional thresholds of the parameters tested was observed only for GFR in both males (59 versus 14%; p<0.001) and females (61 versus 41%; p<0.001), and for ferritin in females (15 versus 5%; p<0.001). In multiple linear regression analysis haemoglobin values were significantly associated only with GFR (both in men and women). DISCUSSION AND CONCLUSION: The results of this study suggest that impaired renal function might be the major determinant of anaemia in the very elderly. Accordingly, the cost-effectiveness of screening for nutritional deficiencies in older individuals is doubtful, since it would be associated with substantial expenditure and limited diagnostic efficiency.