The purpose of screening is early diagnosis and treatment. Screening tests are administered to people without current symptoms, but who may be at high risk for certain diseases or conditions.

Screening Tests

A hematocrit or a hemoglobin test can detect anemia. These tests are part of a complete blood count, which is often done during an annual physical exam, or as part of your prenatal exams. A hematocrit is also done every time you give blood.

Infants and children are often screened for iron deficiency anemia as part of a well child evaluation.


A hematocrit is the percentage of your blood that is red cells. The test fills a tiny glass tube with a drop of blood from your finger and spins it down in a centrifuge so that all the cells settle to the bottom. Normal adult values are 42%-52% in men and 37%-48% in women.


The amount of hemoglobin (oxygen-carrying chemical) in your blood is also tested. Normal adult values for men are 13.8–17.2 grams per deciliter of blood (g/dL) and 12.1–15.1 gm/dL for women.

Complete Blood Count

The complete blood count (CBC) includes the values above plus a count of red cells, white cells, and platelets. The count is automatically done by a machine. These values plus other calculations create the complete blood count or CBC.

Screening Guidelines

The US Preventive Services Task Force (USPSTF) recommends screening for:

  • Non-pregnant women at 5-10 year intervals (more often for those at risk of iron-deficiency because of heavy menstrual blood loss or poor iron intake)
  • Pregnant women at the first prenatal visit

The USPSTF does not have recommendations for screening men or postmenopausal women.

For children, the American Academy of Pediatrics recommends screening at one year. Some children, like those who were born prematurely, may need to be screened more frequently.