Quick cases in haematology

Our latest eLearning module features five cases in haematology, exploring common but challenging scenarios arising from abnormal full blood count results. Complete the full module on Pulse 365 today.

Abnormal full blood count results are often benign or transient, but may be early indicators of significant underlying pathology, including gastrointestinal disease, malignancy, nutritional deficiency or haematological disorders.

This case-based learning module explores five common but often challenging scenarios: unexplained iron deficiency, isolated macrocytosis, persistent thrombocytosis, functional iron deficiency in heart failure and iron deficiency without anaemia.

Learning objectives

This module will support you to:

Apply a systematic approach to investigating iron deficiency anaemia (IDA) when initial gastrointestinal investigations are normal, including consideration of small bowel pathology, malabsorption and non-GI sources of blood loss.
Identify and appropriately investigate causes of persistent macrocytosis in the presence of normal B12 and folate, including recognising when to suspect alcohol-related disease, endocrine disorders or early haematological malignancy.
Differentiate between reactive and clonal thrombocytosis and carry out appropriate investigations, including malignancy screening and timely referral for suspected myeloproliferative neoplasms.
Recognise functional iron deficiency in patients with heart failure and understand the role of intravenous iron therapy in improving symptoms and clinical outcomes, even in the absence of anaemia.
Assess and manage iron deficiency without anaemia (IDWA), including how to investigate and tailor management based on individual risk factors and clinical context.

Case 1: Iron deficiency anaemia with normal GI investigations

The case: This 64-year-old woman presented with iron deficiency anaemia. She was referred for GI investigations which showed normal gastroscopy and colonoscopy. What further investigations should I be doing to explore the potential cause of this?

It is worth pausing to consider if this is true iron deficiency anaemia (IDA) – evidenced by low ferritin, low transferrin saturation and raised total iron-binding capacity (TIBC) – and not another microcytic process. Once confirmed, and with the GI tract apparently clear, we need to look beyond the obvious.

The small bowel is the next consideration. Coeliac disease should not be overlooked as a possible cause – about 3-5% of ‘unexplained’ IDA cases in adults are due to coeliac disease. Even in older adults and without classic symptoms, perform coeliac serology (tTG or endomysial antibodies). If positive, refer for duodenal biopsy confirmation. If negative but suspicion of an underlying cause persists, discuss with gastroenterology about video capsule endoscopy (VCE) to assess for angiodysplasia, small bowel tumours or Crohn’s.

Medication history often holds clues: NSAIDs, low-dose aspirin and anticoagulants can cause chronic occult bleeding, sometimes without mucosal ulceration. Consider also ureteric or gynaecological sources – in postmenopausal women, recurrent urinary blood loss or uterine bleeding may explain anaemia, warranting pelvic ultrasound or urology input if there’s microscopic haematuria.

If still stuck, think of malabsorption syndromes that reduce iron uptake rather than cause loss. The main culprits are atrophic gastritis and Helicobacter pylori infection, both of which impair gastric acid and hence iron absorption. H. pylori may also contribute through low-grade blood loss and inflammation. Non-invasive testing (urea breath test or stool antigen) is reasonable, particularly in older adults with refractory IDA and normal endoscopies. That said, it’s not yet clear if eradication makes a significant difference to iron absorption.

Autoimmune or atrophic gastritis (often associated with pernicious anaemia or autoimmune thyroid disease) is another important though under-recognised cause. Low serum B12 may point in that direction. In such patients, iron deficiency can predate B12 deficiency by years.

Finally, in the small subset of patients where everything is negative and anaemia recurs, consider long-term iron supplementation as a maintenance strategy, with periodic review rather than repeated invasive testing – particularly in frail or elderly individuals where risks of further investigation outweigh the potential yield.

Case 2: Persistent macrocytosis with normal B12 and folate

The case: I have just been looking through the lab results of one of my patients, a 58-year-old man, whose blood tests show a persistent macrocytosis, with a normal B12 and folate. What else might cause this and how should I proceed?

Macrocytosis is common and often benign, but persistent mean corpuscular volume (MCV) elevation requires further, structured investigation.

If B12 and folate are normal, the next potential culprits are alcohol excess, liver disease, hypothyroidism, haematological disorders (myelodysplastic syndromes [MDS], haemolysis or recent blood loss), and certain drugs (hydroxycarbamide, azathioprine, methotrexate, phenytoin, antiretrovirals). A good alcohol history is key: even modest daily intake can elevate MCV before liver enzymes budge.

Screen with TFTs, LFTs, reticulocyte count and peripheral smear. If reticulocytes are raised, think haemolysis or blood loss recovery. If smear shows dysplastic or target cells, or if cytopenias develop, refer to haematology – myelodysplastic syndrome (MDS) is not rare in men of this age.

If all is normal and there’s no clinical concern, a pragmatic approach is to monitor six-monthly to annually. But remember, subtle macrocytosis is sometimes the earliest clue to MDS – persistent unexplained cases, especially with cytopenias or abnormal morphology, warrant haematology advice and guidance or review and possible bone marrow biopsy.

Click here to complete the full module and log 2 CPD hours towards revalidation

Module reviewed by: Dr Keith Hopcroft, GP and Pulse clinical advisor

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