How Paroxysmal Nocturnal Hemoglobinuria Is Diagnosed

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disorder that can appear with "red flag" symptoms like dark-colored urine and others that are much less noticeable. It can be hard to diagnose PNH because it is rare.

This article will provide an overview of symptoms that may warrant testing for PNH, and what to expect from your doctor during the process of being diagnosed with the condition.

A blue gloved hand holding a vial of blood.

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Self-Checks/At-Home Testing

PNH is mainly diagnosed in a lab or by your doctor. There are no at-home testing kits or self-checks that can accurately diagnose the condition. For the most accurate results, you should see your doctor for a special urine test (urinalysis).

What Does PNH Look Like?

Paroxysmal nocturnal hemoglobinuria (PNH) is a condition that can have symptoms such as weakness and fatigue. You might not know that you feel this way due to PNH because, often, there are processes happening in your body that you are not aware of or able to feel.

With PNH, your blood cells are lacking some of the proteins that protect them from destruction. Your red and white blood cells might be damaged or destroyed faster than they can be replaced. There are many blood cells in your body, which means that this process can happen for some time without you noticing.

Here are some of the most common symptoms of PNH and how often they are reported by people with the condition:

  • Fatigue (80%)
  • Shortness of breath (64%)
  • Red blood cells in the urine (62%)
  • Abdominal pain (44%)
  • Chest pain (33%)
  • Blood clotting problems (16%)
  • Kidney problems (14%)

Physical Examination

If you are experiencing symptoms that do not go away with rest or lifestyle changes, call your doctor and make an appointment.

Several physical symptoms can develop with PNH, but many of them are also common in other conditions.

Your doctor will do a physical examination and assess you for certain symptoms that could indicate that you have PNH, including:

Labs and Tests

Your doctor will need to perform a series of blood tests to make a formal diagnosis of PNH. A blood test called flow cytometry is considered the gold standard for diagnosing PNH.

The test allows your healthcare team to examine a large number of cells all at once. It's particularly useful for examining and classifying different types of blood cells.

Other test results that can be used to diagnose PNH include:

  • Abnormal complete blood cell counts (CBC)
  • Elevated reticulocyte count
  • Increased lactate dehydrogenase (LDH)
  • Increased bilirubin
  • Decreased haptoglobin
  • Urinalysis that shows hemoglobinuria
  • Antibody testing

Most of these tests require a small amount of blood. The blood collection is done in a laboratory or healthcare facility using a small needle inserted into your arm.


Imaging tests are not typically used to diagnose PNH. However, X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) can be used to rule out other conditions that could be causing your symptoms or to check for complications of PNH.

Imaging tests can help diagnose some complications of PNH, including:

Differential Diagnoses

Many symptoms of PNH also occur in other conditions. Therefore, your healthcare team will need to rule out other conditions that could be causing your symptoms through a process called a differential diagnosis.

Typical differential diagnoses for PNH include:

  • Coombs-negative hemolytic anemia
  • Hereditary spherocytosis
  • Microangiopathic hemolytic anemias
  • Drug- or toxin-induced hemolytic anemias
  • Disseminated intravascular coagulation (DIC)
  • Autoimmune hemolysis
  • Venous thrombosis
  • Myeloproliferative disorders
  • Solid tumors that can lead to increased blood clotting
  • Thrombophilia
  • Cytopenias
  • Bone marrow failure
  • Aplastic anemia
  • Myelodysplastic syndromes (MDS)


Paroxysmal nocturnal hemoglobinuria (PNH) is a rare condition involving the blood cells that can share symptoms with a number of other conditions. It's not passed through families. The diagnosis relies on clinical assessments and laboratory testing. You may need to have many tests performed—or even seek out a second opinion—before you get a diagnosis.

A Word From Verywell

If you have symptoms of PNH, schedule an appointment with your doctor. While you have about a one in a million chance of developing PNH, the only way to rule it out is to have tests.

There are no accurate home tests or screening tests for the condition. A diagnosis is usually made using blood testing and your doctor's differential diagnosis to rule out other possible conditions to explain your symptoms.

Frequently Asked Questions

  • Can I diagnose myself with paroxysmal nocturnal hemoglobinuria?

    No. There are no home tests that can be used to diagnose PNH. If you think you have PNH, you should call your doctor to set up an appointment.

  • Are the symptoms of PNH obvious?

    Some symptoms of PNH can be noticeable, like fatigue or shortness of breath. However, these symptoms also occur in many other conditions. Blood testing is the best way to get an accurate diagnosis of PNH.

  • Will I need a CT scan or an MRI?

    You usually will not need imaging tests for a diagnosis of PNH; however, these tests can be done to rule out other conditions or complications of PNH like blood clots.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Cançado RD, da Silva A, Araújo, Freire Sandes A, et al. Consensus statement for diagnosis and treatment of paroxysmal nocturnal haemoglobinuria. Hematol. Transfus. Cell Ther. September 2021;43(3):341-348. doi:10.1016/j.htct.2020.06.006

  3. National Organization for Rare Disorders. Paroxysmal nocturnal hemoglobinuria. Updated 2019.

  4. National Institutes of Medicine. Paroxysmal nocturnal hemoglobinuria. Updated April 7, 2021.

  5. Johns Hopkins Medicine. Paroxysmal nocturnal hemoglobinuria (PNH).

  6. Brodsky R. Paroxysmal nocturnal hemoglobinuria without GPI-anchor deficiency. J. Clin. Invest. October 2019;129(12):5074-5076. doi:10.1172/JCI131647

  7. The Aplastic Anemia and MDS Association. PNH: Paroxysmal nocturnal hemoglobinuria.

By Rachael Zimlich, BSN, RN
Rachael is a freelance healthcare writer and critical care nurse based near Cleveland, Ohio.