Platelet Count

Normal results: In a healthy individual, normal platelet count is 1,50,000-4,50,000 per microlitre of the blood. Platelet count less or more than the normal range is an indication of an underlying condition, which needs to be diagnosed and treated.

Abnormal results:

• A higher than normal platelet count indicates thrombocythemia, in which, the bone marrow produces excess platelets, and the platelet count is more than one million. It may lead to increased formation of blood clots, which interferes with the blood supply to vital organs of the body such as brain and heart. The underlying cause of this condition is not yet known.
• Thrombocytosis is another medical condition that occurs due to excessive platelets, but here the platelet count is not as high as thrombocythemia. It does not involve an abnormal bone marrow. Thrombocytosis is caused due to inflammation, infections, cancer and certain medicines.
• A lower than normal platelet count indicates thrombocytopenia, in which, the bone marrow produces fewer than normal platelets or platelet destruction in body. The underlying medical conditions causing thrombocytopenia include kidney disease, infections, pregnancy, cancer and defects in the immune system. Some medicines can also lead to thrombocytopenia.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. This information is purely from an educational perspective and is in no way a substitute for medical advice from a qualified doctor.

A blood sample is obtained from a vein in the arm or fingertip in children and adults. The heel stick method, pricking of the heel with a lancet, is used to withdraw blood from infants. Moderate pain is felt in the region where the needle is pricked. A throbbing sensation and slight bruising may be experienced after blood is collected.

Most often, no special preparation is needed before a platelet count test is performed.

However, it is important to keep the doctor informed about the following:

• Childbirth, residence in higher altitude areas and excessive physical exertion
• Oral contraceptives and oestrogen supplements
• The date of menses as the platelet count reduces mildly just before menses
• The duration of pregnancy as the platelet count reduces mildly at full term
• Hereditary disorders due to genetic defects in the platelet, eg, Chediak-Higashi syndrome, Wiskott-Aldrich syndrome, Down syndrome, Glanzmann's Thrombasthenia, May-Hegglin syndrome and Bernard-Soulier disease.

All of these factors may affect platelet count, leading to incorrect interpretation of results.

Platelet count is generally a part of a complete blood count (CBC) test; it is done in routine health check-ups. A platelet count is of specific importance in conditions, such as bleeding disorders when the individual experiences uncontrolled or unexplained bleeding. Bleeding disorders are generally associated with a reduced platelet count. Platelet count is recommended and performed in individuals with the following symptoms:

• Heavy bleeding in women during menstruation
• Gastrointestinal bleeding detected in a stool test
• Red spots on skin, which appear like rashes
• Excessive and prolonged bleeding from a minor cut
• Bleeding from the rectum, mouth or nose with no obvious injury
• Heavy and uncontrolled bleeding from a small wound
• Unexplained bruising
• Purple spots on  skin surface due to bleeding under the skin

It is also performed in individuals with excessive clotting, which occurs due to a rise in platelet count.