Disorders
CHAPTER 22 Anaemia in older people
Angela M. Sanford
Division of Geriatrics, Saint Louis University School of Medicine, St Louis, Missouri, USA
Background
In 1968, the World Health Organization (WHO) formally established the definition of anaemia. It was categorized as a haemoglobin level less than 13 g/dL in men and less than 12 g/dL in women.1 The normal haemoglobin range is adjusted for children, pregnancy, gender, smokers, and those who live at higher altitudes, but there have yet to be any large studies specifically focused on normal haemoglobin values in older people. Additionally, the original cohort used to establish the normal values of haemoglobin at the population level excluded elderly patients, and thus controversy exists regarding normal values for older people. A natural decline in haemoglobin levels in older adults is accepted, but at this time, it is not clear if this happens due to the ageing process, underlying chronic disease, or some other unknown cause. While the absolute value of haemoglobin is important when considering if someone is anaemic, it is also important to take into account the trend of haemoglobin in an individual and whether there has been a substantial change from previous values.
Anaemia in older people is often underdiagnosed and undertreated despite being associated with increased morbidity and poor quality of life in older adults.2 Older people with anaemia have been found to have added impairments in activities of daily living and functional status,3 increased weakness and fatigue,4 and higher rates of frailty,5 cognitive decline,6 depression,3 and fractures.7 In addition, hospitalized older adults with anaemia have longer lengths of stay and increased readmission rates.8,9 While anaemia is very common in those with advanced age, it is not considered a normal aspect of ageing, and older adults with anaemia should undergo a workup to evaluate the cause of anaemia and establish a diagnosis. Once a diagnosis is established, a treatment plan can be implemented. Treatment of anaemia typically requires a multi‐faceted plan. Resolution may be difficult to achieve – particularly if the anaemia is due to underlying chronic inflammation and disease.
Anaemia is typically classified by either underlying aetiology10 or morphology and size of red blood cells (RBCs) as determined by the mean‐corpuscular volume (MCV) of haemoglobin. If classified by aetiology, typical groupings consist of impaired production of RBCs (nutritional deficiencies, chronic inflammation, and clonal disorders), acute loss of RBCs (bleeding), accelerated RBC destruction (haemolytic and sickle cell anaemia), and ‘unexplained’ anaemia (Figure 22.1). If classified by morphology, the MCV of RBCs is used, and classifications include microcytic, normocytic, and macrocytic anaemias. It is more common to use the classification system relying on underlying aetiology and important to recognize that the MCV often does not reflect the underlying anaemia pathogenesis. For example, in vitamin B12 deficiency anaemia, RBCs may be either normocytic or macrocytic, but it is commonly thought of as a purely macrocytic anaemia. In nutritional deficiencies, MCV is frequently in the normal range, particularly early in the disease course, and can also be normal when multiple diseases are present concurrently, making it less useful for establishing an aetiology.
Epidemiology
Anaemia is quite common in older adults, with prevalence rates of 10–25% in those over 65 years of age.11,12 The risk of developing anaemia increases with age: up to 50% of those older than 80 are anaemic.11 It is also quite prevalent in older hospitalized patients and can affect up to 50% of nursing home residents.13 Men, particularly African American males, appear to be at higher risk.13 Worldwide and across all age groups, the most common type of anaemia is iron deficiency anaemia. However, the most common type of anaemia found in the older adult population is anaemia of chronic disease. One study conducted on Austrian seniors ages 64 and above by Bach et al. evaluated the causes of anaemia in older age groups and found anaemia of chronic disease to have the highest prevalence (62.1%), followed by anaemia of chronic kidney disease (11.3–45.1%, depending on glomerular filtration rate used), multifactorial causes (28.1%), iron deficiency (14.4%), clonal disorders (10%), folate deficiency (6.7%), and vitamin B12 deficiency (2%)13 (Figure 22.2).
Figure 22.1 Aetiology of anaemia.
Nutritional deficiencies
Iron deficiency anaemia
Iron deficiency is the most common nutritional disorder worldwide and is therefore the most common type of anaemia across all age groups worldwide. Iron deficiency anaemia (IDA) is also one of the most treatable forms of anaemia and results from one of the following: inadequate iron intake, decreased iron absorption, increased iron demand, or accelerated iron loss.14 Inadequate iron intake can occur in those with malnutrition or who follow specialized diets. Older adults may be at higher risk of malnutrition due to higher frequencies of social isolation leading to poor appetite and less food consumption, financial constraints limiting the buying of high‐quality food, lack of transportation to obtain food, and inability to prepare meals due to illness or immobility.15 Decreased iron absorption is also more common in older adults and can result from medications such as proton pump inhibitors, which decrease the acidity of the stomach and prevent conversion of iron to its absorbable form.16 Decreased iron absorption is also more likely in those who have had stomach or bowel resection and those with inflammatory bowel diseases. Achlorhydria, caused by the autoimmune destruction of gastric parietal cells (i.e. atrophic gastritis or pernicious anaemia) or bacterial overgrowth, frequently results in disrupted iron absorption. Increased iron demand can occur in states of rapid red blood cell turnover such as in chronic kidney disease, where many factors lead to earlier red blood cell destruction, or haemolytic anaemias, where there is autoimmune‐driven destruction of red blood cells. Accelerated iron loss frequently occurs in acute and chronic bleeding states.
Figure 22.2 Most prevalent types of anaemia in older adults.
Figure 22.3 Diagnostic laboratory values for iron deficiency anaemia, anaemia of chronic disease, and anaemia of chronic kidney disease.
Iron is found in many varieties of food sources, with red meat containing the highest amounts, and is necessary for the synthesis of oxygen transport proteins found in haemoglobin and oxidation reductions necessary for cellular metabolism. It is consumed in the ferric formulation (Fe3+) and converted by the acidity of the stomach to the ferrous formulation (Fe2+). It is absorbed primarily in the duodenum, with lesser amounts absorbed in the jejunum through the iron transporter ferroportin, and is then bound to the protein transferrin, which acts as its carrier in the blood.17 If not needed in muscle or for immediate use in red blood cell production, iron is stored bound to the protein ferritin in the liver. Because we consume only
