Immune thrombocytopenia (ITP)
Only nine or ten adults in every 100,000 have ITP, a rare autoimmune disease affecting platelet production and characterised by fatigue, bruising and bleeding[1-3]. Many treatment options involve weakening the immune system with drugs that have limited evidence for use in ITP. But now, more evidence-based treatments may mean a better life is possible for people living with ITP[4].
What is ITP?
ITP stands for immune thrombocytopenia. The disease was previously known as idiopathic thrombocytopenic purpura[5]. If the condition persists, it is called chronic immune thrombocytopenia. Thrombocytopenia that is not caused by a previous disease is known as primary ITP. If the disease is caused by another condition affecting the immune system (such as HIV), it is referred to as secondary ITP.
Immune thrombocytopenia that is diagnosed in absence of any other identifiable immune disorder is called Primary ITP. Secondary ITP is when low platelet counts are due to another disorder affecting the immune system, such as an underlying infection (e.g. HIV) or an autoimmune disease[6].
What are platelets?
Platelets are tiny, colourless cell fragments in the blood that form clots which stop or prevent bleeding. They’re called platelets because when viewed through a microscope in their inactive state they resemble plates. A platelet measures about 2 microns (about 0.002 millimetres) in diameter – that’s about one-quarter of the diameter of a red blood cell. Platelets are made in our bone marrow and those that are not used in clotting usually survive for seven to ten days before being destroyed naturally in the body.
Platelets help the body form clots, growing sticky tentacles and adhering to each other
When a blood vessel becomes damaged it sends out a signal. When the platelets receive that signal, they respond by travelling to the area and transforming into their active state, growing sticky tentacles that make the platelets adhere to each other and form a clot[7].
The blood needs a sufficient platelet count in order to clot normally. A normal platelet count ranges from 150,000 to 400,000 platelets per cubic millimetre of blood[8]. A person who has a platelet count below 150,000 is said to have thrombocytopenia[8].
ITP is not the same as haemophilia, although some of the symptoms are similar. The main differences are:
- Haemophilia is hereditary, while ITP is not believed to be hereditary and often has no clear cause.
- ITP, unlike haemophilia, can go into remission – meaning that the symptoms can go away.
- Haemophilia is a bleeding disorder in which the blood does not clot properly; people with ITP have reduced platelets but the rest of their clotting mechanism works normally.
How common is ITP?
The incidence of new diagnoses is around 3.3 for every 100,000 people each year[1]. The prevalence of ITP among adults – how many people have the condition at any one time – is in the order of 9.5 cases per 100,000[1]. Worldwide, this would lead to a total of more than 750,000 people affected by ITP[1]. More women are affected than men[1].
When treating ITP, it is important to see the bigger picture and see the patient as a whole person, considering the full range of symptoms can that affect quality of life.
ITP patients in a number of countries around the world have taken the initiative to set up advocacy organisations, running awareness campaigns to increase visibility of the disease and offering practical support to people who live with ITP.
How is ITP diagnosed?
ITP is identified by a diagnosis of exclusion. There is no single blood test that can prove whether a patient has ITP, so it has to be a process of eliminating other possible causes based on a patient’s history, on examinations, and on the results of initial tests[9]. In diagnosing ITP, the healthcare provider will carry out blood tests to identify the underlying causes of low platelets. ITP is diagnosed if blood tests show that only the platelet count is low while the platelets, red blood cells and white blood cells all look normal[10].
In cases of persistent ITP, a bone marrow biopsy may be recommended to rule out other causes for a reduced platelet count[10]. A small sample of bone marrow is taken under local anaesthetic and examined under the microscope[10]. If the bone marrow is free from abnormalities and other blood tests are normal, then chronic ITP will be diagnosed[10].
What are the symptoms of ITP?
The symptoms of immune thrombocytopenia can be very different for different individuals. In general, the severity of symptoms will vary according to how far the platelet count is below the normal range.
- If the platelet count is in the range 50,000-150,000 platelets per cubic millimetre of blood there is usually no bleeding or bruising and the patient may not be aware of the condition[8].
- If the platelet count falls below 50,000 some bruising may occur[8].
- Below 20,000, bruising and petechiae (pinpoint blood spots under the skin) are more likely[8].
Common symptoms
- Fatigue [10][11]
- Bruising that is unexpected or unusually severe [10][11]
- Petechiae – rash of tiny red or purple spots [10][11]
- Purpura – red or purple discoloured spots on the skin [10][11]
- Prolonged or excessive bleeding from cuts [10][11]
- Nosebleeds [10][11]
- Bleeding gums [10][11]
- Black blisters in the mouth [10][11]
- For female patients, heavy periods [10][11]
Living with ITP
Immune thrombocytopenia has a substantial, multifaceted impact on patients' health-related quality of life (HRQoL).[8]
The impact of ITP will vary from person to person and the reasons for symptoms may also differ.
Fatigue is one of the main symptoms of ITP reported by patients. Various studies show that at least half of people living with ITP experience fatigue that can often interfere with everyday life.[11]
The fatigue experienced by people with autoimmune diseases such as ITP is different from the normal, temporary fatigue we all feel after a taxing activity such as concentrating for a long time or vigorous exercise, or after a poor night’s sleep. That kind of fatigue goes away with rest. But ITP-related fatigue can be debilitating and can interfere with people’s ability to engage in everyday activities. In some cases when the platelet count is low it goes beyond a feeling of tiredness to brain fog and an inability to carry out simple tasks like recalling a two-digit number after ten seconds.[12] ITP patients have described how they are obliged to take time out from their work or studies to sleep during the day.[13]
People living with ITP may worry about how bleeding could affect their work and social activities. For most people, the impact of ITP on their quality of life seems to reduce after the first year.[14] This may be partly because they learn coping strategies to adapt and live with the condition, and partly because they respond well to treatment.
Many of those living with ITP report impacts on their emotional wellbeing, with emotional and mental stress and anxiety, and a greater risk of depression.[15][16]
What treatments are available?
ITP affects different people in different ways and a range of treatments are available. People with mild cases may need nothing more than regular monitoring and frequent platelet checks. However, adults who develop chronic ITP will in many cases eventually need treatment.[1][8]
There is no cure for ITP but there are treatments that can raise the platelet count and thereby counteract the symptoms and help people to live with the disease.
Treatments include steroids as an initial short-term measure, immunoglobulin, drugs to reduce the immune system response that is causing the platelets to be destroyed, and TPO-RAs (thrombopoietin-receptor agonists), which can lift the platelet count by boosting platelet production in the bone marrow.
References:
[1] NORD, National Organization for Rare Disorders. Immune Thrombocytopenia. Available at https://rarediseases.org/rare-diseases/immune-thrombocytopenia/ [Accessed September 2023]
[2] Platelet Disorder Support Association (PDSA) Available at: https://www.pdsa.org/what-is-itp.html [Accessed September 2023]
[3] Hill, Q.A. and Newland, A.C., 2015. Fatigue in immune thrombocytopenia. British journal of haematology, 170(2), pp.141-149.
[4] Provan, D. and Newland, A.C., 2015. Current management of primary immune thrombocytopenia. Advances in therapy, 32, pp.875-887.
[5] Rodeghiero, F. et al. 2009. Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: report from an international working group. Blood, The Journal of the American Society of Hematology, 113(11), pp.2386-2393.
[6] Platelet Disorder Support Association (PDSA). ITP and Genetics. Available at: https://www.pdsa.org/patients-caregivers/disease-information/genetics.html [Accessed September 2023]
[7] John Hopkins Medicine. What are platelets and why are they important? Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/what-are-platelets-and-why-are-they-important#:~:text=A%20blood%20vessel%20will%20send,a%20spider%20or%20an%20octopus. [Accessed September 2023]
[8] Norfolk and Norwich University Hospitals NHS Foundation trust. Immune Thrombocytopenia. Available at: https://www.nnuh.nhs.uk/departments/haematology-department/non-malignant-haematology/immune-thrombocytopenia/ [Accessed September 2023]
[9] Visweshwar, N., et al. 2022. Primary immune thrombocytopenia: a ‘diagnosis of exclusion’?. Blood Coagulation & Fibrinolysis, 33(6), pp.289-294.
[10] The ITP Support Association. ITP in Adults. Available at https://www.itpsupport.org.uk/index.php/en/itp-in-adults [Accessed September 2023]
[11] Cooper, N., et al. 2021. Immune thrombocytopenia (ITP) World Impact Survey (I‐WISh): Impact of ITP on health‐related quality of life. American journal of hematology, 96(2), pp.199-207.
[12] Sobi.com. Changing ITP Together. Available at www.sobi.com/en/stories/changing-itp-together [Accessed September 2023]
[13] Kruse, C., Kruse, A. and DiRaimo, J., 2020. Immune thrombocytopenia: the patient's perspective. Ann. Blood, 6.
[14] Trotter, P. and Hill, Q.A., 2018. Immune thrombocytopenia: improving quality of life and patient outcomes. Patient Related Outcome Measures, pp.369-384.
[15] Mathias, S. et al. 2008. Impact of chronic Immune Thrombocytopenic Purpura (ITP) on health-related quality of life: a conceptual model starting with the patient perspective. Health and quality of life outcomes, 6, pp.1-14.
[16] Cooper, N. et al. 2021. Qualitative study to support the content validity of the immune thrombocytopenia (ITP) Life Quality Index (ILQI). British Journal of Haematology, 194(4), pp.759-766.