Diagnosis of anemia

Anemia more often than not may be diagnosed by clinical features alone. A simple blood test is usually enough to confirm the diagnosis of the condition.

Diagnostic workup however is needed to ascertain the underlying cause of the anemia. (1-5)

History and physical examination

Diagnosis begins with a detailed history and physical examination.

The physician enquires about dietary habits to determine lack of iron and vitamin B12 or folates in diet.

They will ask about the medications that the patient takes. Aspirin for example leads to stomach ulcers that may bleed regularly to cause anemia.

The doctor may ask about menstrual patterns and history of heavy bleeding. Any other disease or family history of anemias is also enquired.

A detailed physical examination entails examination of the abdomen for enlarged spleen or liver. Signs of jaundice, kidney disease or cancers are looked for.

Severe anemia may lead to heart failure. This occurs when the heart is not pumping blood around the body efficiently.

A rectal examination that entails insertion of a lubricated gloved finger gently into the rectum may help detect hidden focus of rectal bleeding that is causing the anemia.

A pelvic examination to exclude cause of bleeding may be needed in women with heavy periods and excessive menstrual bleed loss.

Pregnancy may lead to anemia and needs to be ruled out as a cause of anemia.

Laboratory tests for diagnosis of anemia

Diagnosis of anemia includes the following laboratory analyses and tests (1-5):

  • A routine blood count. Blood sample taken from a vein in the arm is assessed for blood counts. Anemia is detected if the level of haemoglobin is lower than normal.

    There may be fewer red blood cells than normal. Under the microscope the RBCs may appear smaller and paler than usual in case of iron deficiency anemia.

    The small size is termed microcytic anemia. In vitamin B12 of folate deficiency the RBCs may appear pale but larger than their usual size. This is called macrocytic anemia.

  • Ferritin stores – Ferritin is a protein that stores iron. If the blood levels of ferritin are low it indicates low iron stores in the body and helps detect iron deficiency anemia.
  • Blood tests include mean cell volume (MCV) and red blood cell distribution width (RDW).
  • Reticulocyte count is a measure of young RBCs. This shows if the RBC production is at normal levels.
  • Vitamin B12 and folate levels in blood – these help detect if the anemia if due to deficiency of these vitamins.
  • Bone marrow analysis to detect too many immature RBCs as seen in aplastic anemia or blood cancers. Lack of iron in bone marrow also points towards iron deficiency anemia.

    Bone marrow is obtained by inserting a hollow needle into the breast bone or hip bone and withdrawing small amount of the marrow. The sample is then placed on a glass slide and stained with special dyes. This is examined under the microscope.

  • Iron binding capacity. Lower capacity of iron binding indicates iron deficiency anemia.
  • In women of African, Mediterranean or Southeast Asia ancestry, mild anemia that does not respond to iron therapy may be due to thalassemia minor or sickle cell trait.

    These can be detected by genetic tests and electrophoresis of blood. Hemoglobin electrophoresis identifies various abnormal hemoglobins in the blood. It is used to diagnose sickle cell anemia, the thalassemias, and other inherited forms of anemia.

  • Complete work ups including assessment of hidden foci for bleeding in the abdomen or intestines. Liver and kidney functions are evaluated to check if the anemia is due to chronic liver or kidney disease.

Further Reading

Last Updated: Jun 4, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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