A low hemoglobin count is a commonly seen blood test result. Hemoglobin (Hb or Hgb) is a protein in red blood cells that carries oxygen throughout the body.
In many cases, a low hemoglobin count is only slightly lower than normal and doesn't affect how you feel. If it gets more severe and causes symptoms, your low hemoglobin count may indicate you have anemia.
A low hemoglobin count is generally defined as less than 13.5 grams of hemoglobin per deciliter (135 grams per liter) of blood for men and less than 12 grams per deciliter (120 grams per liter) for women. In children, the definition varies with age and sex. The threshold differs slightly from one medical practice to another.
Low hemoglobin count
A low hemoglobin count can be associated with a disease or condition that causes your body to have too few red blood cells. This can occur if:
- Your body produces fewer red blood cells than usual
- Your body destroys red blood cells faster than they can be produced
- You experience blood loss
Diseases and conditions that cause your body to produce fewer red blood cells than normal include:
- Aplastic anemia
- Certain medications, such as anti-retroviral drugs for HIV infection and chemotherapy drugs for cancer and other conditions
- Hodgkin's lymphoma (Hodgkin's disease)
- Hypothyroidism (underactive thyroid)
- Iron deficiency anemia
- Chronic kidney disease
- Lead poisoning
- Multiple myeloma
- Myelodysplastic syndromes
- Non-Hodgkin's lymphoma
- Vitamin deficiency anemia
Diseases and conditions that cause your body to destroy red blood cells faster than they can be made include:
- Enlarged spleen (splenomegaly)
- Sickle cell anemia
A low hemoglobin count can also be due to blood loss, which can occur because of:
- Bleeding from a wound
- Bleeding in your digestive tract, such as from ulcers, cancers or hemorrhoids
- Bleeding in your urinary tract
- Frequent blood donation
- Heavy menstrual bleeding
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.