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Interpreting a Full Blood Count

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A full blood count is one of the most commonly requested tests in primary care and provides a considerable amount of diagnostic information. It's correct interpretation is therefore crucial in many conditions. In this resource, we present a number of common scenarios requiring interpretation of the full blood count. Complete the 10 self assessment questions to be presented with a certificate of 1hr of continuous professional development for inclusion in your annual learning journal.

On successful completion of this resource, the user should:

Be able to interpret the common abnormalities noted on a full blood count

Understand the various components represented in a full blood count

A full blood count is one of the most commonly requested tests in primary care and provides a considerable amount of diagnostic information. It's correct interpretation s therefore crucial in many conditions. In this module, we present a number of common scenarios requiring interpretation of the full blood count. Complete the 10 self assessment questions to be presented with a certificate o 1hr of continuous professional development for inclusion in your annual learning journal.

On successful completion of this resource, the use should:

Understand the various components presented in a full blood count

Primary Care

A 16 year old girl attends clinic as she has been feeling unwell with lethargy and a sore throat for a week or so. Her full blood count is reported as follows:

This young girl presents with typical features of glandular fever and the FBC with the presence of 

. Glandular fever is a viral infection, caused by the Epstein Barr Virus (EBV), that affects mostly young adults. Common symptoms include a high temperature, swollen neck nodes, sore throat, and fatigue. It is spread via saliva, and can be spread by kissing, coughs, sneezing, or sharing utensils such as glasses/spoons. If a patient is infected with glandular fever, they are contagious for at least two months after the initial infection. There is no cure for the virus, treatment is aimed at relieving the symptoms, such as painkillers to reduce the fever and pain. In addition to the FBC, one could also request IgM to Epstein-Barr Virus to confirm the diagnosis.

http://www.nhs.uk/Conditions/Glandular-fever/Pages/Introduction.aspx

Question 1

The following blood count was obtained on a 37 year old male who complained of feeling down and depressed. His wife told him to go to clinic as she has been concerned about his behaviour of late.

What is the most likely cause for this result?

This patient has a high MCV (macrocytosis) on his FBC, which means the red cells are larger than normal. Due to his recent behaviour change and feeling depressed the most likely explanation for this is alcohol consumption. This is a common cause of an elevated MCV. Vitamin B12 / folate deficiency, and hypothyroidism are also causes for macrocytosis, but alcohol is more common. Iron deficiency anaemia presents with a low MCV value (microcytic anaemia)

http://www.patient.co.uk/doctor/Macrocytosis-and-Macrocytic-Anaemia.htm

Question 2

The following full blood count was obtained on a 30 year old female who complained of tiredness.

This young female is anaemic, her Hb level is below 12g/dl, which is microcytic (ie low MCV indicating that the red cells are small). The most likely diagnosis is iron deficiency anaemia and this is often due to blood loss during menstruation in a woman of this age. Common symptoms include feeling weak, tired, headaches, sore tongue and shortness of breath.The next step would be to check the ferritin concentration which is expected to be low, and iron therapy should be started. In an older postmenopausal female or in a male, other sources of bleeding must be considered, e.g from the GI tract from peptic ulcer disease. If there is no obvious bleeding, malignancy should be considered e.g colonic or gastric carcinoma. Other possible causes include inefficient dietary intake in vegetarians, or increased requirements for iron such as in pregnancy.

http://www.patient.co.uk/doctor/Iron-Deficiency-Anaemia-(IDA).htm

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001610/

Question 3

A 75 year old man attends clinic as he has been feeling unwell of late with tiredness and fatigue. He has also noticed a modest weight loss over the last two to three months. His full blood count reveals:

This patient has presented with weight loss and fatigue and the full blood count reveals excess lymphocytes in the blood suggestive of 

 rather than infection. It is the most common of all leukaemias and typically affects individuals over the age of 60. The associated anaemia as seen here is likely due to the proliferation of lymphocytes at the expense of red cells. Similarly, other blood components can be suppressed too. Haemochromatosis is associated with a higher than normal iron concentration in the blood.

http://www.nhs.uk/conditions/leukaemia-chronic-lymphocytic/Pages/Introduction.aspx

http://www.nlm.nih.gov/medlineplus/ency/article/000532.htm

Question 4

A 55 year old woman with a history of adequately treated hypothyroidism presents with tiredness. Her full blood count reveals:

This patient has an anaemia which is macrocytic (high MCV). The most likely diagnosis here is vitamin B12 deficiency particularly as the patient has another autoimmune condition, hypothyroidism. 

 causing vitamin B12 deficiency is an autoimmune condition resulting in the loss of intrinsic factor. Vitamin B12 binds to the intrinsic factor, and is then absorbed at the end of the small intestine. Without the intrinsic factor, vitamin B12 is unable to bind, and therefore it does not get absorbed from the gut.
This is treated with vitamin B12 injections.

http://emedicine.medscape.com/article/204930-overview

Question 5

A 26 year old female presents with tiredness and this blood picture.

Which of the following would be the most appropriate test to request for the further investigation of this blood count?

This patient has a low MCV and is anaemic - microcytic anaemia. This is most likely caused by an iron deficiency anaemia and one should request a ferritin concentration to confirm this diagnosis. In a young female this is most likely due to blood loss during menstruation. Iron can be replaced with tablets, and advice needs to be given about dietary sources of iron such as meat, dark green leafy vegetables such as watercress, and avoid drinking too much tea or coffee.

Question 6

A 55 year old male attends clinic as he has been feeling tired and unwell for a couple of months and has been aware of some headaches. He is a smoker of 10 cigarettes daily, is hypertensive and overweight. His full blood count shows:

This patient has an elevated haemoglobin concentration 

. The disease can be primary, due to a proliferative condition, or as is more likely in this case, secondary to stress such as the hypoxia caused from smoking. It can also be caused by dehydration, high blood pressure and obesity known as 'apparent polycythaemia'. The high red cells can result in increased viscosity of the blood which can cause clots eg DVT.

http://www.patient.co.uk/doctor/Polycythaemia-Rubra-Vera.htm

Question 7

A 35 year old Asian male attends clinic as he is concerned that he has put on quite a bit of weight over the last two years and is worried about the risk of developing diabetes. Both his parents have the condition. He is otherwise well and takes no medication, does not smoke nor does he drink. His results reveal:

What is the most likely cause for this full blood result?

The most likely diagnosis in this otherwise well man who has presented with no features of anaemia but concerned more about weight gain is a 

. This is a genetic condition resulting in a reduced production of haemoglobin protein and hence a mild microcytic anaemia. One might differentiate between this and iron deficiency anaemia by checking the ferritin concentration. In thalassaemia trait the ferritin would be normal and in iron deficiency obviously the ferritin would be low.

Question 8

A 40 year old female attends clinic complaining of tiredness and fatigue which have developed over the last two months. Her full blood count reveals the following:

This is a normal full blood count. All parameters are within the normal limits. However, there are many other causes of tiredness and fatigue, such as underactive thyroid, diabetes therefore thyroid function test and fasting plasma glucose should be the next step in the investigation. Furthermore it is important not to overlook mental health conditions such as depression as these patients often presents to primary care services with symptoms similar to the above, so it's important to recognise depression symptoms such as early morning wakening, loss of appetite, feeling tearful and guilty, and low self esteem.

Question 9

A 66 year old male with a long history of chronic disease including immobility from obesity and venous ulcers on the legs presents with increased tiredness. His full blood count shows:

What is the most appropriate interpretation of this full blood count?

This blood count reveals an anaemia with a low haemoglobin concentration and a normal MCV (normocytic). This is the typical 

Haematinics should still be checked as a combination of iron deficiency (causing microcytosis) and vitamin B12 or folate deficiency (macrocytosis) could still present as a normocytic picture.

Interpreting a Full Blood Count

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