From the Guidelines
Vitamin B12 deficiency in the elderly is typically defined as a serum level below 258 pmol/L, as indicated by metabolic B12 deficiency with elevated plasma total homocysteine or methylmalonic acid 1. This definition is crucial because biochemical B12 deficiency and metabolic B12 deficiency are very common in patients with stroke, and both have important consequences, including neuropathy, dementia, and an increased risk of stroke due to hyperhomocysteinemia. Some key points to consider in defining vitamin B12 deficiency in the elderly include:
- Metabolic B12 deficiency is frequently missed because a serum B12 in the normal range is often accepted as ruling out B12 deficiency 1.
- Age-related changes in absorption, particularly decreased gastric acid production and intrinsic factor, contribute to the higher prevalence of B12 deficiency in the elderly population 1.
- The diagnosis should not rely solely on serum B12 levels but should also consider clinical presentation and additional markers such as methylmalonic acid and homocysteine levels, which may be elevated in B12 deficiency even when serum B12 levels appear normal.
- Regular screening and appropriate supplementation are important for this age group, especially considering that B12 deficiency is very common in the elderly, with prevalence rates ranging from 10 to 40% in community-dwelling and institutionalized elderly populations 1. Key factors that support the definition of vitamin B12 deficiency as a serum level below 258 pmol/L include:
- The study by 1 which found that metabolic B12 deficiency was present in 18.1% of patients aged >80 years, and in 10.6% of patients overall.
- The finding that B12 deficiency is very common in India, in part due to a high prevalence of vegetarianism, and that even in adolescents, biochemical B12 deficiency was reported in 32% of study participants in the Haryana region 1.
- The study by 1 which found that 5.9% of elderly men and women in the UK were deficient in vitamin B12, according to serum cobalamin levels, and that estimates of the prevalence of B12 deficiency from elsewhere in Europe tend to be much higher, ranging from 10 to 40% for both community-dwelling and institutionalized elderly populations.
From the Research
Definition of Vitamin B12 Deficiency
- Vitamin B12 deficiency is estimated to affect 10%-15% of people over the age of 60 2
- The laboratory diagnosis is usually based on low serum vitamin B12 levels or elevated serum methylmalonic acid and homocysteine levels 2
- However, there is no consensus or guideline for diagnosis of this deficiency, and it is most often based on clinical symptoms together with laboratory assessment 3
Diagnostic Criteria
- Low serum vitamin B12 level is a common indicator of vitamin B12 deficiency, but the cut-off level to define serum vitamin B12 deficiency is difficult to set 3
- Elevated serum homocysteine or methylmalonic acid level can also indicate vitamin B12 deficiency, but these tests may give false results in some conditions and the reference intervals are not standardized 3
- The diagnosis of vitamin B12 deficiency is often based on a combination of clinical symptoms, laboratory tests, and response to treatment 3
Serum Vitamin B12 Levels
- The studies do not provide a specific cut-off level for serum vitamin B12 deficiency in pmol/L 3, 2, 4, 5, 6
- However, it is mentioned that low serum vitamin B12 levels and vitamin B12 deficiencies are frequently found in the elderly, and supplementation may be necessary for individuals with low or low-normal vitamin B12 levels 4