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How It´s Diagnosed

Your symptoms, test results, and the doctor’s clinical judgment all play an important role in arriving at a diagnosis of atypical-HUS.

Ruling out other causes

The process of diagnosing atypical-HUS often starts with symptoms that are serious enough to cause the patient to go to the doctor or hospital. If it’s determined that the symptoms are caused by thrombotic microangiopathy (TMA), it’s important to identify the underlying cause through further investigations, including a full patient medical and family history, since TMA can occur in a number of different disorders.

There is no single test that confirms a diagnosis of atypical-HUS. Diagnosis typically occurs through a process of elimination that rules out other causes of TMA.


If blood taken from your arm or leg reveals
schistocytes—fragments of damaged or destroyed red blood cells—it can be an indicator of TMA.

Diagnostic tests

These are some of the tests used in the diagnosis of atypical-HUS. Some may be ordered in a hospital setting—for example, if you are having acute symptoms of TMA and have gone to an emergency department. Others may be done later, by your primary care physician or a specialist. Your doctor may not order all of these tests or may order others not listed here.

A sample of blood is taken from an arm or leg to look for the presence of schistocytes—damaged or destroyed red blood cells—which can be an indicator of hemolysis.

This test is used to rule out thrombotic thrombocytopenic purpura (TTP), which has many of the same symptoms as atypical-HUS.

A low level of circulating platelets in your blood can indicate abnormal clotting, which can be an indicator of TMA.

Elevated lactate dehydrogenase (LDH) is a sign of hemolysis—damaged or destroyed red blood cells—which can be an indicator of TMA.

This test helps to determine how well your kidneys are working. Elevated creatinine can be a sign of kidney impairment.

Estimated glomerular filtration rate (eGFR) is a calculation that indicates how well your kidneys are working. It’s based on creatinine level and other factors such as age, gender, and weight. Low eGFR can be a sign of kidney impairment.

A procedure to remove a small piece of kidney tissue that can be examined under a microscope for signs of damage or disease.

Examination of DNA to look for gene mutations known to affect regulation of the complement system. Identifying certain mutations associated with atypical-HUS can be helpful in predicting the likelihood of developing kidney disease or TMA relapse.


Your doctor may refer you to one or more specialists with expertise in the organs and systems affected by atypical-HUS. Please note that this is not a complete list of specialists your doctor may refer you to.

Hematologist/Oncologist - Specializes in blood disorders.

Genetic Counselor - Specializes in helping people understand the medical, psychological, and familial implications of genetic contributions to disease.

Nephrologist - Specializes in kidney disorders.

Neurologist - Specializes in disorders affecting the brain and central nervous system.

Could you use a helpful tool to guide your conversations with your doctor and any specialists you are referred to?

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