Thrombotic microangiopathies

Thrombotic microangiopathies (TMAs) are a group of rare diseases characterised by the formation of small clots in very small blood vessels. These clots can lead to a reduced platelet count, destruction of red blood cells (haemolytic anaemia), and damage to various organs, particularly the kidneys, brain and heart. The main forms of TMA are thrombotic thrombocytopenic purpura (TTP) and atypical haemolytic uraemic syndrome (aHUS).

TMAs constitute a diagnostic and therapeutic emergency. Rapid management can now considerably improve patients’ prognosis.

Symptoms may appear suddenly and vary from person to person:

• Severe fatigue related to anaemia;
• Bruising or bleeding related to a drop in platelet count;
• Decreased kidney function;
• High blood pressure;
• Neurological disorders (headaches, confusion, visual disturbances, seizures);
• Abdominal pain or involvement of other organs.

Diagnosis is based on a rapid assessment carried out by specialised teams.

Tests generally include:

• A complete blood count;
• Tests for signs of haemolysis;
• Examination of a blood smear to look for schistocytes;
• Assessment of kidney function;
• Measurement of ADAMTS13 activity to identify TTP;
• Specialised analyses of the complement system when atypical haemolytic uraemic syndrome (aHUS) is suspected;
• Additional tests to identify an underlying cause.

The management of thrombotic microangiopathies at HUB is based on close collaboration between several specialties to ensure rapid diagnosis and treatment tailored to each patient.

Nephrology expertise

As the kidneys are frequently affected in thrombotic microangiopathies, patients receive a specialist assessment within the HUB Nephrology Department. Nephrologists provide diagnosis, monitor kidney function and, when necessary, implement specialised treatments such as dialysis or targeted treatments for complement-mediated forms.

Multidisciplinary care

Depending on the clinical situation, various specialists work together to care for the patient:

• Nephrology;
• Haematology;
• Internal medicine;
• Intensive care;
• Neurology;
• Cardiology;
• Medical genetics;
• Specialised laboratories.

This multidisciplinary approach ensures comprehensive, personalised care.

Treatment depends on the type of thrombotic microangiopathy (TMA) identified.

Depending on the situation, it may include:

• Plasma exchange;
• Immunomodulatory treatments;
• Treatments targeting the complement system;
• Management of an underlying cause (infection, autoimmune disease, medication, pregnancy, transplantation, etc.);
• Specialised renal care, including dialysis if necessary.

HUB actively contributes to the advancement of knowledge in the field of rare kidney diseases and thrombotic microangiopathies.

Where relevant, patients may benefit from access to clinical research protocols, specialised diagnostic analyses, and the expertise of national and international reference centres.

This research activity helps improve diagnosis, understanding of disease mechanisms, and the development of new treatments.

• Recognised expertise in nephrology and complex kidney diseases;
• Specialised multidisciplinary collaboration;
• Access to specialised diagnostic tests;
• Management of emergency situations;
• Participation in expert networks and research projects;
• Personalised support for patients and their families.

Some thrombotic microangiopathies, particularly forms associated with genetic abnormalities of the complement system, may manifest during childhood. HUB works closely with the Queen Fabiola Children’s University Hospital (HUDERF) to ensure coordinated care for children and adolescents affected by these rare diseases.

For patients receiving paediatric care, a transition programme is organised between the paediatric and adult teams. This gradual transition ensures continuity of care, the transfer of essential medical information and support for the young patient towards autonomous care in adulthood.

Nephrologists, paediatricians, geneticists and other relevant specialists work closely together to ensure optimal follow-up throughout the care pathway, from childhood to adulthood.