To check for aHUS, your doctor will do a complete blood count (CBC) test. A CBC test will measure your red blood cell and platelet count since having low counts can be a sign of aHUS.

You will also need a blood test to check how well your kidneys are working. Kidney health can be measured by a test called eGFR.  eGFR is calculated using your creatinine level, as well as age, sex, and race.

The signs of aHUS can look similar to another condition called thrombotic thrombocytopenia purpura (TTP). For a doctor to decide whether you have aHUS or TTP, you will need to have a blood test that measures the level of a protein called ADAMTS13 in your blood. Low levels of this protein can show you have TTP instead of aHUS. Knowing whether you have aHUS versus TTP is important since the two diseases have different treatments.