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Home / For clinicians / Diagnosis guides / Paroxysmal nocturnal hemoglobinuria (PNH) / Checklist

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Suspect-and-test checklist

Paroxysmal nocturnal hemoglobinuria (PNH)

Almost always acquired, not inherited. Sources flag Coombs-negative hemolysis, unusual-site clots and marrow failure; a flow cytometry result is read with clinical features.

ICD-10-CMD59.5Trial Friend for Clinicians

1Red flags present

Hemolysis

Unusual-site thrombosis

Swallowing, belly and erections

Marrow

Kidney and lungs

2Already labeled as

3Family to test

4Testing, in the order the sources describe

  1. CBC, reticulocytes, LDH, bilirubin, haptoglobinInterest Group minimal criteria for diagnosis and categorization.
    Result
  2. Direct antiglobulin (Coombs) testHill: Coombs-negative hemolytic anemia is a reason to request flow.
    Result
  3. Peripheral blood flow cytometryAt least 2 GPI-anchored proteins, on at least two cell lineages.
    Result
  4. FLAER-based white cell assayGranulocytes and monocytes; CD157 tested as a replacement for CD24 and CD14.
    Result
  5. CD235a/CD59 red cell assayDetected as few as 20 type III red cells per million.
    Result
  6. High-sensitivity analysisDetects as few as 0.01% PNH cells; routine analysis finds 1% or more.
    Result
  7. Marrow aspirate, biopsy and cytogeneticsInterest Group: for classification. Hill: not needed for diagnosis; advised with severe pancytopenia.
    Result

5Results the sources say do not rule it out

  • No dark urine. Only 26% of 80 patients reported hemoglobinuria at presentation.
  • Red cell results after transfusion. Granulocytes are unaffected; red cells are best tested before transfusion or after at least 1 month without one.
  • A standard single-color flow result. In 2005 it was sensitive to about 3% GPI-deficient cells.
  • Normal LDH. The LDH rule does not apply to subclinical PNH in aplastic anemia or refractory anemia-MDS.

6Specialists the sources name

Diagnosis code: D59.5 Paroxysmal nocturnal hemoglobinuria [Marchiafava-Micheli]Codes patients often carry before diagnosis are listed in the online guide.
Full guide and sourcesEvery point here is sourced in the online guide, which also has a patient note to print.
Trial Friend, trialfriend.com/for-clinicians. Key sources: International PNH Interest Group (2005); Nature Reviews Disease Primers (2017); UK population study (2021); ICCS/ESCCA 2018, Part 1; ICCS/ESCCA 2018, Part 2; ICCS 2010 guidelines; all 23 with links in the online guide. Checked November 9, 2026. A reference checklist for licensed clinicians that summarizes published sources. It is not a diagnostic tool, a score or a protocol, and it does not replace clinical judgment, local practice or the prescribing information. Not coding advice. Trial Friend never receives anything written or typed on this sheet.