How Is aHUS Diagnosed?

It's important to accurately diagnose aHUS because it has signs and symptoms similar to those of other diseases1

Some of the signs and symptoms of aHUS include: confusion; diarrhea, nausea and vomiting; shortness of breath; fatigue; heart symptoms and kidney symptoms.1-5

Lab Tests

Certain lab tests can help your doctor determine if you may have aHUS. In particular, he or she can look at your red blood cell and platelet counts to see if they are low. Creatinine levels can be measured to see how well your kidneys are working.6 Although aHUS is a genetic disease, testing for specific genes is not necessary for your doctor to diagnose and treat aHUS.7 The ADAMTS13 laboratory test can help differentiate aHUS from other diseases.8

Testing for Similar Illnesses

Because aHUS is so rare, there is a lot for you and your doctors to learn about it.9 Many of the signs and symptoms can be confused with other illnesses that also cause TMAs in your system.10

25% of patients with aHUS have a coexisting disease or condition due to another distinct underlying cause.7

Diagnosis of a coexisting disease or condition should not rule out a diagnosis of aHUS7

Thrombotic thrombocytopenic purpura (TTP) causes clots that damage small blood vessels in the body. But TTP is caused by low levels of a protein in the blood called ADAMTS13. If a patient has less than 5% of normal ADAMTS13 levels, then TTP is the likely disease.4

STEC-HUS is caused by an E coli infection. People who have this disease are most likely to have diarrhea. A doctor can check the patient's stool sample to see if STEC bacteria or shiga toxin are present.8,10,11 If you have been told you have STEC-HUS but your symptoms don't go away, you may actually have aHUS. Talk with your doctor if your symptoms reoccur.12

Want to know more?

1. Laurence J. Atypical hemolytic uremic syndrome (aHUS): making the diagnosis. Clin Adv Hematol Oncol. 2012;10(suppl 17):1-12. 2. Legendre CM, Licht C, Muus P, et al. N Engl J Med. 2013;368:2169-2181. 3. Sellier-Leclerc A-L, Frémeaux-Bacchi V, Dragon-Durey MA, et al; French Society of Pediatric Nephrology. Differential impact of complement mutations on clinical characteristics in atypical hemolytic uremic syndrome. J Am Soc Nephrol. 2007;18:2392-2400. 4. Noris M, Mescia F, Remuzzi G. STEC-HUS, atypical HUS and TTP are all diseases of complement activation. Nat Rev Nephrol. 2012;8:622-633. 5. Noris M, Caprioli J, Bresin E, et al. Relative role of genetic complement abnormalities in sporadic and familial aHUS and their impact on clinical phenotype. Clin J Am Soc Nephrol. 2010;5:1844-1859. 6. Caprioli J, Noris M, Brioschi S, et al; for the International Registry of Recurrent and Familial HUS/TTP. Genetics of HUS: the impact of MCP, CFH, and IF mutations on clinical presentation, response to treatment, and outcome. Blood. 2006;108:1267-1279. 7. Sarode R, Bandarenko N, Brecher ME, et al. Thrombotic thrombocytopenic purpura: 2012 American Society for Apheresis (ASFA) consensus conference on classification, diagnosis, management, and future research. J Clin Apher. 2013; DOI: 10.1002/jca.21302. [Epub ahead of print]. 8. Cofiell R, Kukreja A, Bedard K, et al. Poster presented at the 55th Annual Meeting of the American Society of Hematology; December 7-10, 2013; New Orleans, LA. Abstract 2184. 9. Waters AM, Licht C. aHUS caused by complement dysregulation: new therapies on the horizon. Pediatr Nephrol. 2011;26:41-57. 10. Heinen S, Pluthero FG, van Eimeren VF, et al. Monitoring and modeling treatment of atypical hemolytic uremic syndrome. Mol Immunol. 2013;54:84-88. 11. Boogaerts MA, Roelant C, Goosens W, et al. Complement activation and adult respiratory distress during intermittent flow apheresis procedures. Transfusion. 1986;26:82-87. 12. Riedl M, Hofer J, Rosales A, et al. Initiale plasmatherapie bei patienten mit atypischem HUS: kein negative Vorhersagewert für das outcome nach einem jahr. Klin Padiatr. 2011; 223-P031 DOI: 10.1055/s-0031-1273832.