Idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder caused by
an abnormally low level of blood platelets, small disc-shaped cells
essential to blood clotting (coagulation). ITP describes both the cause
and symptoms of the condition: idiopathic means that the disorder has no
apparent cause; thrombocytopenia refers to a decreased number of blood
platelets; and purpura refers to a purplish or reddish-brown skin rash
caused by the leakage into the skin of blood from broken capillaries. ITP
is as of 2004 often called immune thrombocytopenic purpura rather than
idiopathic because studies in the early 2000s have shown the presence of
autoimmune antibodies in the blood. Other names for ITP include purpura
hemorrhagica and essential thrombocytopenia.
Coagulation, or clotting, is a complex process in which specific proteins
found in blood plasma combine with other blood components, including
platelets, to form clots and prevent blood loss. Platelets are tiny
colorless disc-shaped cells in the blood that collect (aggregate) in blood
vessels to form a plug when a vessel is injured. The platelet plug then
binds coagulation proteins to form a clot that stops bleeding. A
deficiency in platelets or a disorder that affects platelet production can
disrupt clotting and severely complicate blood loss from accidental
injury, surgery, and specific diseases or conditions in which bleeding can
occur. ITP affects the overall number of blood platelets rather than their
function. The normal platelet level in adults is between 150,000 and
. Platelet counts below 50,000/mm
increase the risk of dangerous bleeding from trauma; counts below
increase the risk of spontaneous bleeding.
ITP may be either acute or chronic. The acute form occurs in children
between ages two and six. Although chronic ITP is most common in adult
females, 10 to 20 percent of children with ITP have the chronic form.
Acute ITP affects children of both sexes between the ages of two and six
years. The chronic form, although most common in adult females between the
ages of 20 and 40, is found in 10 to 20 percent of children with ITP. ITP
does not appear to be related to race, lifestyle, climate, or
Causes and symptoms
In children, ITP is usually triggered by a virus infection, most often
, cytomegalovirus (CMV), or Epstein-Barr virus (EBV). ITP usually begins
about two or three weeks after the infection.
Acute ITP is characterized by bleeding into the skin or from the nose,
mouth, digestive tract, or urinary tract. The onset is usually sudden.
Bleeding into the skin takes the form of purpura or petechiae. Purpura, a
purplish or reddish-brown rash or discoloration of the skin, and
petechiae, small round pinpoint hemorrhages, are both caused by the
leakage of blood from tiny capillaries under the skin. In addition to
purpura and petechiae, spontaneous
may occur. In extreme cases, ITP may cause bleeding into the lungs,
brain, or other vital organs.
Chronic ITP has a gradual onset and may have minimal or no external
symptoms. The low
may be discovered in the course of a routine blood test. Most parents
consult a pediatrician or primary care doctor after noticing their child
has the typical purpuric skin rash, frequent nosebleeds, or bleeding from
the digestive or urinary tract.
In adults, ITP is considered an autoimmune disorder, which means that the
body produces antibodies that damage some of its own products—in
this case, blood platelets. Some adults with chronic ITP may have other
autoimmune diseases such as lupus (systemic lupus erythematosus or SLE),
rheumatoid arthritis, or scleroderma. Women with ITP may experience
unusually heavy or lengthy menstrual periods. Risk factors for the
development of chronic ITP in adults include being female, age over 10
years at onset of symptoms, bruising, and having another known autoimmune
When a child bruises easily, has frequent nosebleeds, bloody stools, or
develops a purplish or reddish-brown rash or tiny spots of hemorrhage, the
symptoms should be reported to the pediatrician or
doctor, especially if they are noticed in the weeks following measles or
chickenpox or a virus infection such as mononucleosis.
—One of a group of disorders, like rheumatoid arthritis and
systemic lupus erythematosus, in which the immune system is overactive
and has lost the ability to distinguish between self and non-self. The
body's immune cells turn on the body, attacking various tissues
—Substances in the blood, also known as coagulation factors, that
act in sequence to stop bleeding by triggering the formation of a clot.
Each clotting factor is designated with a Roman numeral I through XIII.
—Refers to a disease or condition of unknown origin.
—Plural, petechiae. A tiny purple or red spot on the skin
resulting from a hemorrhage under the skin's surface.
—A cell-like particle in the blood that plays an important role
in blood clotting. Platelets are activated when an injury causes a blood
vessel to break. They change shape from round to spiny,
"sticking" to the broken vessel wall and to each other to
begin the clotting process. In addition to physically plugging breaks in
blood vessel walls, platelets also release chemicals that promote
—A corticosteroid medication often used to treat inflammation.
—A group of disorders characterized by purplish or reddish brown
areas of discoloration visible through the skin. These areas of
discoloration are caused by bleeding from broken capillaries.
—Surgical removal of the spleen.
—A persistent decrease in the number of blood platelets usually
associated with hemorrhaging.
Children with ITP will usually have platelet counts below 20,000/mm
and a prolonged clotting time. The size and appearance of the platelets
may be abnormal, which is observed microscopically. The red blood cell
count (RBC) and white blood cell count (WBC) are usually normal, although
about 10 percent of individuals with ITP are also anemic (have reduced
RBCs and hemoglobin). The bone marrow test yields normal results.
Detection of antiplatelet antibodies in the blood usually confirms a
diagnosis of ITP.
There is no specific treatment for ITP except to manage symptoms. In most
cases, the disorder will resolve within two to six weeks without
medications or surgery. Nosebleeds can be treated with ice packs when
necessary. General care may include asking parents to watch for bruising,
petechiae, or other signs of recurrence. Parents are also advised to avoid
giving the child aspirin, ibuprofen, or other over-the-counter
medications because these drugs are known to lengthen the clotting time
Children with acute ITP who are losing large amounts of blood or bleeding
into their central nervous system require emergency treatment. This may
include transfusions of platelets, intravenous immunoglobulins, or
prednisone. Prednisone is a steroid medication that decreases the effects
of antibodies on platelets and eventually lowers antibody production. If
the child has been treated before for ITP and has not responded to
prednisone or immunoglobulins, surgery may be required to remove the
spleen (splenectomy), an organ that sometimes stores platelets and keeps
them out of the general blood circulation. Splenectomy is usually avoided
in children younger than five years because of the increased risk of a
severe postoperative infection. In older children, however, splenectomy is
recommended if the child has been treated for 12 months without
improvement, if the ITP is very severe or is getting worse, or if the
child begins to bleed into the head or brain.
Children with chronic ITP can be treated with prednisone, immune globulin,
or large doses of intravenous gamma globulin. Although 90 percent of those
with ITP respond to immunoglobulin treatment, it is an expensive
treatment. Response to prednisone therapy is about 80 percent. Platelet
transfusions are not recommended for routine treatment of ITP. If platelet
levels do not improve within one to four months, or high doses of
prednisone are required, splenectomy may be recommended. If the patient is
an adolescent female with extremely heavy periods, splenectomy may also be
recommended. Adults treated with splenectomy usually experience remission
of chronic ITP. All medications for ITP are given either orally or
intravenously; intramuscular injection is avoided because of the
possibility of causing bleeding into the skin.
The prognosis for recovery from acute ITP is good; 80 percent of those
affected recover without special treatment. The prognosis for chronic ITP
is also good; most individuals experience long-term remission. In rare
instances, however, ITP can cause life-threatening hemorrhage or bleeding
into the central nervous system.
Because as of 2004 the exact cause for ITP is unknown, no specific
preventive measures are recommended. However, episodes of bleeding can be
prevented in children with ITP by discouraging rough contact
or other activities that increase the risk of trauma. To reduce the risk
of ITP associated with other illnesses, children can be immunized against
childhood diseases and kept away as much as possible from other children
or adults with known or unidentified viruses.
The sudden onset of ITP-like symptoms can be a concern, but the presence
of a rash or bruising is not a signal for alarm because there are so many
possible causes of these symptoms in childhood. Parents can be generally
watchful, but not fearful. The symptoms to be alert for are frequent
nosebleeds or frequent bruising with no specific cause, particularly if
the child has had a recent illness or virus. It is helpful to remember
that ITP, whether acute or chronic, has an excellent prognosis and may
cause bleeding but not life-threatening hemorrhage in most cases. Parents
can ask the pediatrician when in doubt and understand that simple blood
and coagulation tests can be performed to rule out ITP.
Alving, Barbara M.
Blood Components and Pharmacologic Agents in the Treatment of Congenital
and Acquired Bleeding Disorders.
Basel, Switzerland: S. Karger AG, 2000.
The Merck Manual of Medical Information
, 2nd Home Edition. Edited by Mark H. Beers et al. White House Station,
NJ: Merck & Co., 2003.
National Heart, Lung, and Blood Institute (NHLBI).
6701 Rockledge Drive, PO Box 30105, Bethesda, MD 20824–0105. Web