by Dr. Adele Visser
What is thrombocytopaenia?
Thrombocytopaenia is defined as a reduced platelet count where in most instances the lower threshold is considered to be 150 x 109 per litre in adult patients. The clinical relevance of various levels of thrombocytopaenia differ (Figure 1).
Figure 1.
Clinical definition and relevance of thrombocytopaenia.
What are the causes of thrombocytopaenia?
Various clinical factors will need to be considered in the work-up of a patient presenting with thrombocytopaenia, including factors like pregnancy-state, medication use and prior medical history (figure 2).
Figure 2.
Broad representation of common causes of thrombocytopaenia and diagnostic tools.
What should I consider upon finding my patient to have a thrombocytopaenia?
The first question should be whether the level of thrombocytopaenia justifies transfusion. The SANBS guidelines should be utilized in this regard as platelet transfusions are both costly and a very limited resource.
The second issue should be to determine the underlying cause.
Typically, a clinical history and clinical examination will allude to the obvious causes, however, should this approach not yield a diagnosis, a purely pragmatic approach of demonstrating sufficient or insufficient production should be followed (this is attained through performing a bone marrow aspirate with trephine biopsy.
Of note, the diagnosis of immune-mediated platelet destruction (Also referred to as Ideopathic Thrombocytopaenic Purpura – ITP) is a diagnosis of exclusion.
References
- Clinical Guidelines for the Use of Blood Products in South Africa – SANBS
- Essential Haematology 5th Edition, Hoffbrand AV, Moss PAH and Pettit JE.