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.

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).

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:

• Fatigue
• Weakness
• Tiny red spots on your skin
• Bruising
• Bleeding that is difficult to control
• Jaundice
• Swelling in your limbs
• Shortness of breath
• Pale skin

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

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:

• Blood clots
• Kidney disease
• Chest pain
• Difficulty swallowing
• Abdominal pain
• Pulmonary hypertension

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)

Summary

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.