Chapter 6 Answers to case study questions

6.1 Interpretation of a blood film

Most common features include: Small spherocytes (yellow arrows), large spherocytes (not macrocytes as there is no central pallor) (ochre arrows), a microcyte (blue arrow), echinocytes (white arrow), degmacyte (or bite cell) (green arrows) and acanthocytes (black arrow). There is also a considerable anisocytosis, and so the RDW will be large. The absence of even one white blood cell is not surprising, but the absence of platelets implies a thrombocytopenia.

6.2 Anaemia in a young woman

The patient is a young woman from the Far East with a history of tiredness and lethargy but few other symptoms of note. Abnormalities include a low haemoglobin, MCH, MCV and MCHC, and a raised red blood cell count, reticulocytes and ESR. The Hct is borderline low. These, linked with the history, lead to a diagnosis of anaemia. Because the MCV is low, we can further qualify the diagnosis in describing the condition as microcytic anaemia.

The leading causes of microcytic anaemia are iron deficiency and haemoglobinopathy. The former is easy to diagnose with iron studies, principally transferrin and ferritin. Diagnosis of the two major haemoglobinopathies, sickle cell disease and thalassaemia, is also relatively simple with tests such as the sickle solubility test, electrophoresis, and HPLC.

6.3 Diagnosis of haemoglobinopathy by electrophoresis

This case study is a series of electrophoresis patterns. The pattern in Sample 1 is identical to that of AS and AD, therefore additional tests are required in order to differentiate between the two and so make a final diagnosis. The Sample 2 pattern matches that of SC, providing a confident diagnosis. The pattern of Sample 3, of three distinct bands, does not match that of any of the controls. There is a line that corresponds with A, another that matches S and a third that could be either C or E. One ex-planation for this anomaly is contamination, but another is that the sample is from a patient who has recently had a transfusion. Sample 4 has a line that corresponds to haemoglobin S, but there is a second line which has migrated a small distance further towards the cathode. As there is no control sample that matches up to this line, we are unable to identify it from the existing panel. It may therefore be due to a minor haemoglobin species, and will demand more complex analyses to define its identity. Sample 5 has only a single line in the same position as the AA control, thus defining its diagnosis.

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