Signs of Anemia and What a Low Blood Count Means

What being "anemic" means

Red blood cells contain hemoglobin, an iron-rich protein that carries oxygen from the lungs to every tissue. When hemoglobin falls, tissues get less oxygen and the heart works harder to compensate. That produces the signs of anemia.

A blood test called a complete blood count (CBC) shows:

Severity is graded roughly as mild (10 to 12 g/dL in women, 11 to 13 g/dL in men), moderate (8 to 10 g/dL) and severe (below 8 g/dL).

Signs and symptoms of anemia

Mild anemia often causes no symptoms and is found on a routine test. As it worsens:

• Tiredness and lack of energy that rest does not fix
• Pale skin, pale lips, nail beds and inner eyelids. On darker skin, paleness shows best inside the lower eyelid and on the gums and palms
• Breathlessness on stairs or walking uphill
• Fast or pounding heartbeat (palpitations)
• Dizziness or light-headedness, especially on standing
• Headaches and poor concentration
• Cold hands and feet
• Chest pain on exertion in people with heart disease

Clues to the cause

• Iron deficiency: brittle, spoon-shaped nails, sore tongue, cracks at the corners of the mouth, hair loss, cravings for ice or non-food items (pica), and restless legs.
• B12 deficiency: tingling hands and feet, unsteadiness, memory problems, a smooth red tongue.
• Hemolysis (red cell breakdown): yellow skin or eyes and dark urine.
• Bone marrow problems: frequent infections, easy bruising or bleeding, because other blood cells are low too.

Common causes

Iron deficiency

Iron deficiency anemia is the most common type worldwide. Causes include heavy periods, pregnancy, low dietary iron, poor absorption (celiac disease, after stomach surgery) and slow bleeding from the gut. In men and in women after menopause, iron deficiency needs investigation of the stomach and bowel, because ulcers, polyps and colorectal cancer can bleed silently.

Chronic kidney disease

The kidneys make erythropoietin, the hormone that tells bone marrow to produce red cells. In chronic kidney disease, levels fall and anemia develops, usually once kidney function drops below about 30 to 45% of normal. It causes the same signs as other anemias: fatigue, pale skin, breathlessness and feeling cold. It is common in older adults, including women over 70, because CKD becomes more common with age and is often linked to diabetes and high blood pressure. See anemia due to chronic kidney disease.

Chronic illness and inflammation

Long-term conditions such as rheumatoid arthritis, inflammatory bowel disease, infections and cancer cause anemia of chronic disease, where inflammation locks iron away from the marrow.

Vitamin deficiencies

Vitamin B12 deficiency (from pernicious anemia, a vegan diet, metformin or acid-reducing medicines) and folate deficiency produce large red cells.

Inherited conditions

Sickle cell disease and thalassemia are more common in people of African, Mediterranean, Middle Eastern and South Asian ancestry.

Anemia in older adults

About 1 in 10 adults over 65 is anemic. In older people, symptoms are easily put down to aging, but anemia increases the risk of falls, confusion, heart failure and hospital admission. Often more than one cause is present, for example CKD plus iron deficiency. A new anemia in an older adult should always be investigated rather than accepted as normal.

What tests to expect

After a low hemoglobin, a doctor will usually order:

1. Repeat CBC with red cell indices and a reticulocyte count
2. Iron studies: ferritin (iron stores; a low level confirms iron deficiency), transferrin saturation
3. Vitamin B12 and folate
4. Kidney and liver function, and thyroid tests
5. A blood film to look at the shape of red cells
6. Celiac antibody test in iron deficiency
7. Endoscopy and colonoscopy for iron deficiency without an obvious cause, especially in men and in women after menopause

What to do if you have signs of anemia

• See your primary care doctor for a blood test before starting iron tablets. Taking iron without a diagnosis can hide a bleeding source.
• Bring a list of medicines, including aspirin, NSAIDs and blood thinners, which can cause gut bleeding.
• Note how heavy your periods are, any change in bowel habit, and your diet.
• Do not take iron supplements long term without monitoring, as too much iron is harmful.

For full details of the types of anemia and how each is treated, see the main anemia guide.

Frequently asked questions

What are the first signs of anemia?

The earliest signs are usually tiredness, low energy, and breathlessness on exertion such as climbing stairs. Pale skin, a fast heartbeat, dizziness and headaches often follow. Mild anemia may cause no symptoms and is often found on a routine blood test.

What hemoglobin level is considered anemia?

The World Health Organization defines anemia as hemoglobin below 13 g/dL in men, below 12 g/dL in non-pregnant women and below 11 g/dL in pregnancy. Labs may use slightly different reference ranges, and normal values vary with age and altitude.

What does anemia caused by kidney disease look like?

Anemia from chronic kidney disease causes tiredness, weakness, pale skin, feeling cold, breathlessness and poor concentration, the same as other anemias. It develops gradually as kidney function falls and is common in older adults with diabetes or high blood pressure.

Can anemia be serious?

Mild anemia is usually not dangerous by itself, but it can signal a serious cause such as bleeding from the gut or kidney disease. Severe anemia can strain the heart and cause chest pain, heart failure or fainting.

Should I take iron if I think I am anemic?

Get a blood test first. Not all anemia is from iron deficiency, and iron will not help other types. Iron can also mask the signs of hidden bleeding that needs investigation. If iron deficiency is confirmed, your doctor will advise on supplements.