Example B of quiz type 1: Ethical issues in Medical Science

This is a quiz question that was developed by Diana Quinn and used within a Medical Science course to develop graduate quality 1, the body of knowledge associated with the profession, and graduate quality 3, problem solving skills.

Points of interest

·       No correct or incorrect answer options

·       Language of learning incorporated in feedback to support personal development of understandings

·       Developing relational understanding from uni-structural and multi-structural understandings (Biggs, 1999)

Please select the most likely option in response to this scenario. Three days after untreated acute blood loss, a previously healthy 20 year old male has anaemia with reticulocytosis and:
a) thrombocytopaenia
b) thrombocytosis
c) little change in platelet count

No answer marked as correct

Feedback to option a

I can see why you might have chosen thrombocytopaenia.  Thrombocytopenia means that the platelet count is lower than the normal reference range. Immediately after acute blood loss there is indeed a reduction in the absolute number platelets within the blood. Whole blood (white cells, red cells and platelets) have been lost in equivalent proportions. However, after three days, the bone marrow of a previously healthy male has responded to the blood loss.  Erythropoietin (the hormone that triggers the production of erythrocytes) has worked in the bone marrow to produce a reticulocytosis (increase in the immature erythrocytes). Similarly, a simultaneous release of thrombopoietin would have triggered a mild to moderate thrombocytosis. Therefore, three days after untreated acute blood loss, if there is anaemia and reticulocytosis, there is likely to also be thrombocytosis.

Feedback to option b

Well done for suggesting thrombocytosis - I agree that this is the most likely outcome to this scenario!  Immediately after acute blood loss there logically would be a reduction in the absolute number platelets. After three days, the bone marrow would have responded to the blood loss through the action of erythropoietin (hence the reticulocytes) and thrombopoietin to result in a mild to moderate thrombocytosis. However, did you know that chemicals such as alcohol can depress bone marrow function? If this 20 year-old male had consumed large amounts of alcohol immediately before the accident that triggered the bleeding, than the bone marrow's response would be significantly reduced!

Feedback to option c

Platelet counts do tend to fluctuate in response to stimuli. In this situation there may well be a balance between the thrombocytopaenia triggered by be acute blood loss and the recovery thrombocytosis, resulting in little change in the overall platelet count. It is important to remember that other chemicals, such as alcohol and other drugs, can also impact on the rate of cell division and thus bone marrow function. We know little about these additional environmental impacts within this scenario. What we do know however is that there is a reticulocytosis, suggesting that the bone marrow is working satisfactorily in response to the hormone erythropoietin. For this reason, it is likely for thrombocytosis to also be present.

 

J. Biggs, (1999) “Teaching for Quality Learning at University: What the Student Does”. Open University Press, UK.