Anemia is a shortage of hemoglobin or of healthy red blood cells, so the blood carries less oxygen than the body needs. It is a finding, not a diagnosis: the number tells you oxygen delivery is down, not why. Symptoms are unspecific and easy to blame on a busy life – tiredness, breathlessness on stairs, pale skin, cold hands, poor concentration – and mild cases often produce none at all. It grows more common with every decade of adult life, but it is never a normal feature of aging; it always has a cause worth finding.
What it measures
Anemia is defined by the Hemoglobin concentration on a complete blood count, from an ordinary venous draw, reported in g/dL in the US and g/L elsewhere. The same panel prints hematocrit, red blood cell count, mean corpuscular volume (average cell size) and red cell distribution width, and cell size is the first clue to the cause. Because hemoglobin is a concentration, plasma volume moves it: dehydration hides anemia, while pregnancy and endurance training dilute the value without any loss of red cells. Finding the cause takes a second round of tests – iron studies, vitamin B12 and folate, kidney function, inflammatory markers, reticulocyte count – and, in an adult with iron deficiency and no obvious bleeding, a look at the gut. The Anemia entry at Smart Longevity covers the workup in more depth.
Typical values
| Reading | What it generally means |
|---|---|
| Hemoglobin below 13 g/dL (130 g/L) in men | Anemia by the long-standing WHO definition |
| Below 12 g/dL (120 g/L) in non-pregnant women | Anemia; individual laboratories set slightly different limits |
| Below 11 g/dL (110 g/L) in pregnancy | Anemia in pregnancy, where blood volume expands faster than red cell mass |
| Low mean corpuscular volume (small cells) | Usually iron deficiency; also thalassemia trait, which is lifelong |
| Normal mean corpuscular volume | Acute blood loss, chronic kidney disease, or the anemia of chronic inflammation |
| High mean corpuscular volume (large cells) | Points toward vitamin B12 or folate deficiency, alcohol, some medications, or marrow disease |
Those cut-offs are conventions, not biology. They differ by sex, age, pregnancy, altitude – people living high above sea level carry more hemoglobin – and by the reference interval your own laboratory prints. WHO also grades anemia as mild, moderate or severe; those boundaries are in its current guidance. Compare your result with your earlier results as well as with the range on the report: a steady fall inside the normal band can matter more than a single value sitting just below the line.
Why it matters for longevity
In older adults, anemia is associated in large observational cohorts with higher all-cause mortality, more frailty, falls and fractures, more hospital admissions and faster cognitive decline – and the association holds for mild anemia, not only severe cases. It also lowers exercise capacity directly, since less oxygen reaches working muscle. Most of that risk is probably not caused by the low number itself. Anemia is usually the visible end of something else: slow gastrointestinal bleeding, heavy periods, iron, B12 or folate deficiency, kidney disease that blunts erythropoietin, chronic inflammation, or a marrow disorder. That is exactly why it matters – a new anemia is one of the cheapest early signals medicine has that something else needs looking at.
What changes it
Treatment follows the cause. Iron deficiency is the most common one worldwide: Ferritin reflects stored iron and falls before hemoglobin does, so a normal hemoglobin next to a low ferritin is still iron deficiency and can still leave you tired. Heme iron from meat and fish absorbs best; vitamin C improves absorption from plant sources, while tea and coffee with a meal reduce it. B12 and folate deficiency need replacing at the source, by injection or high-dose tablet when absorption is the problem. The larger levers are usually not nutritional: stopping the bleed, treating the kidney or inflammatory disease behind it, spacing out blood donations, reviewing drugs that irritate the stomach. Some of it you do not control – your sex, and inherited traits such as thalassemia trait. Do not start iron on a hunch: it does nothing for anemia that is not iron-related, and iron overload causes real organ damage.
Related reading
- Which Blood Tests Reflect Aging and How to Read Them
- Chronic Inflammation and Aging: Inflammaging
- Health Through Menopause: A Longevity Guide for Women
- Hemoglobin
Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.