Pancytopenia in adults — a structured approach
A case-based walk-through: from the index CBC to a mechanism-led differential, blood film review and a safe first 24 hours.
By the end of this module you will be able to:
Objectives
- Define pancytopenia and recognise red-flag presentations.
- Apply a mechanism-based framework (production / destruction / sequestration).
- Interpret an index CBC with reticulocyte response and basic indices.
- Identify diagnostic blood-film features for marrow failure.
- Outline a safe first 24-hour management plan including transfusion thresholds.
Mrs. A — 58, pancytopenia on routine CBC
Read the case, hold your initial impressions in mind, then mark that you've noted your differential to continue.
Presentation
Mrs. A is a 58-year-old retired schoolteacher referred by her GP after a routine blood test. She reports six weeks of progressive fatigue, easy bruising on her shins, and two episodes of self-limiting epistaxis. No fever, weight loss, bone pain or recent infection. No new medications. Drinks <5 units/week.
Examination
Pale conjunctivae, scattered petechiae over the lower limbs, no lymphadenopathy, no hepatosplenomegaly. Cardiorespiratory exam unremarkable. No oral ulceration or gum hypertrophy.
Triage
Bloods sent on arrival reveal pancytopenia (see CBC). She is haemodynamically stable but reports fatigue at rest. Initial plan: type & screen, peripheral film, reticulocyte count, LDH, B12/folate, urgent haematology review.
Full blood count on arrival
Click each analyte to see why it matters. Reviewed 1 of 7.
| Analyte | Result | Reference | Flag |
|---|---|---|---|
| Haemoglobin | 78g/L | 120 – 150 | Low |
| MCV | 104fL | 80 – 100 | High |
| Reticulocytes | 12× 10⁹/L | 50 – 100 | Low |
| WBC (total) | 1.8× 10⁹/L | 4.0 – 11.0 | Low |
| Neutrophils | 0.6× 10⁹/L | 2.0 – 7.5 | Low |
| Platelets | 18× 10⁹/L | 150 – 400 | Low |
| LDH | 210U/L | 135 – 225 | Normal |
Annotated film — click each marker
Peripheral film, x100. Reduced cellularity, no abnormal cells, no blasts. · 0 of 4 markers viewed.
Three mechanisms, several causes
Click any node to explore how it fits the mechanism-based framework.
Place each cause under the correct mechanism
Sort each cause of pancytopenia under the dominant mechanism. Some causes overlap — choose the best fit.
Keyboard: Tab to an item, press Enter or Spaceto open a “Move to…” menu, then pick a bucket.
Key concepts — flip to reveal
Click the card to flip. Rate how confident you felt — the app tracks which ones you want to revisit. (0/5 reviewed)
3 clinical MCQs
Answer each question to see the explanation and references instantly.
Which film best matches Mrs. A?
Given the clinical picture and the CBC, which peripheral film is most consistent with the working diagnosis?
Your plan for the next 24 hours
Outline your first 24-hour plan for Mrs. A. Include investigations, transfusion thresholds, supportive measures and what you'd tell her.
Key takeaways
- Pancytopenia = anaemia + leucopenia + thrombocytopenia. Severity drives urgency, not the label itself.
- Use a mechanism-based framework: production, destruction, or sequestration — and let the reticulocyte count and LDH split them.
- Severe neutropenia (<1.0) plus fever is neutropenic sepsis: blood cultures + empirical antibiotics within 1 hour.
- Marrow biopsy with cytogenetics, flow and a PNH clone screen is the diagnostic anchor for marrow-failure syndromes.
- First-24-hour priorities are safety, not certainty: transfusion thresholds, infection prevention, and a clear plan for the next test.