Canterbury DHB

Thrombocytopenia

This section was reviewed by Dr Mark Smith in November 2019. The next review date is November 2022.

A low platelet count (<150 x 10⁹/L) is very common in clinical practice. A review of how to logically work through the various potential causes of thrombocytopenia can be found in Stasi R. How to approach thrombocytopenia. Hematology 2012;191-197.

Thrombocytopenia may arise in a number of clinical situations:

• Drug-induced, most commonly following chemotherapy – see Platelet Transfusions.
• Heparin-induced thrombocytopenia (HIT).
• Autoimmune thrombocytopenia (ITP) - see ASH EPB (Education Program Book) 2018 - Cindy E. Neunert and Nichola Cooper (Evidence-based management of immune thrombocyptopentia: ASH guideline update) Haematology 2018, 568-575).
• Steroid therapy is the principal first-line therapeutic option for ITP. Dexamethasone has recently been shown superior to prednisone, as follows:
  • Dexamethasone is administered orally at 40 mg daily for 4 consecutive days and then stopped.
  • If platelet count remains below 30 × 10⁹/L or there is bleeding by day 10, an additional 4-day course of Dexamethasone (40 mg daily) should be given.
  • For bleeding patients, consideration should be given to administering IV immunoglobulin and platelet transfusion.

  For more information, see Matschke et al. A Randomized Trial Of Daily Prednisone Versus Pulsed Dexamethasone In Treatment Naïve Patients With Idiopathic Thrombocytopenic Purpura. Blood (2013) 122 (21): 325.

• TTP/HUS - see ASH EPB 2012 pp. 604, 610 and 617, and BSH Guidelines for the Management of TTP.

  When considering the potential role of plasma exchange for microangiopathy, measurement of ADAMTS13 levels may be helpful. This assay is available through Canterbury Health Laboratories, coagulation section. Very low levels (<10%) help differentiate either primary immune-depletion or congenital deficiency of ADAMTS13 from other microangiopathies.

• Haematological disorders such as leukaemia, CLL, MDS, aplastic anaemia.

Note: “False” thrombocytopenia may occur when platelets clump in vitro. This form of agglutination is usually EDTA-dependent, and an accurate platelet count can often be obtained if blood is taken into citrate. Beware also of the clotted sample. Repeat CBC to confirm if the result is unexpected.

Note: Intragam-P may be used in a number of conditions, including ITP. A prescription sheet is available.

See also: HealthPathways - Thrombocytopenia.

Topic Code: 6369