What is the likely cause of the intense pain in the patient’s lower right leg? Explain why this patient may be more susceptible to this event.

A 31 year old male presented to his local accident and emergency department with abdominal pain. He has recently been feeling unwell and presents with a suspected upper respiratory tract infection and he has a persistent cough and shortness of breath. Upon examination he has hepatosplenomegaly and has been recently complaining of intense pain in his lower right leg, which is red and warm to the touch. The doctor requests a FBC test and haemoglobin variant analysis. The results are shown below, with normal ranges provided
FBC Results:

Parameter Result Normal range
Haemoglobin 87 g/L 120 – 160 g/L
WBC 12.2 x 109/L 4.0 – 11.0 x 109/L
RBC 2.86 x 1012/L 4.20 – 5.40 x 1012/L
HCT 0.271 L/L 0.35 – 0.47 L/L
MCV 94.7 fL 78 – 98 fL
MCH 30.3 pg 27 – 32 pg
Platelets 337 x 109/L 150 – 450 x 109/L
Neutrophils 6.49 x 109/L (53.2%) 2.0 – 7.5 x 109/L (50 – 98%)
Lymphocytes 4.50 x 109/L (36.8%) 1.5 – 4.0 x 109/L (5 – 50%)
Monocytes 0.54 x 109/L (4.4%) 0.2 – 1.0 x 109/L (2 – 10%)
Eosinophils 0.35 x 109/L (2.9%) 0.1 – 0.8 x 109/L (1 – 4%)
Basophils 0.09 x 109/L (0.7%) 0.01 – 0.2 x 109/L (0 -2%)
RDW 19.9% 11.5 – 13.9%
Reticulocytes (abs) 526 x 109/L 50 – 100 x 109/L
Reticulocytes % 17.5% 0.2 – 2.0%

Haemoglobin Variant analysis by HPLC:

Parameter Result Normal range
Hb F 3.8% 0.1 – 1.0%
Hb A 2.9% 95 – 98%
Hb A2 3.6% 1.8 – 3.5%
Hb variant 89.2%

Data interpretation questions:

Provide a definition of anaemia and explain whether this patient be considered anaemic. Justify your answer. (2 marks)

What is the likely cause of the intense pain in the patient’s lower right leg? Explain why this patient may be more susceptible to this event. (3 marks)

Haemoglobin variant analysis was carried out using HPLC. Explain the principle behind HPLC for haemoglobin variant analysis with reference to one peer-reviewed scientific paper. (4 marks)

What are reticulocytes and why are they likely to be raised in this case? (3 marks)

Haemoglobin variant analysis shows the presence of an abnormal peak on the chromatogram. Interpret the chromatogram to suggest a possible diagnosis for the patient and explain how you arrived at this diagnosis. (4 marks)

Haemoglobin variants cannot be diagnosed on the basis of HPLC results alone. What further diagnostic testing would be appropriate in this case? Explain the principle behind your chosen diagnostic test. (3 marks)

A blood film is requested on this patient by the Biomedical Scientist in the laboratory. Identify the letter which corresponds to a good example of the abnormal features below (1 mark each):

Polychromatic RBC
Target cell
Howell-Jolly body

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