Thrombocytopenia is a condition characterized by abnormally low platelet counts. It has many potential causes, including decreased platelet production in the bone marrow due to things like cancer, viruses, medications, or liver/kidney disease. It can also be caused by increased platelet destruction, such as in immune thrombocytopenic purpura. Symptoms range from bruising and bleeding to internal bleeding in severe cases. Diagnosis involves blood tests to check the platelet count and rule out underlying conditions. Treatment depends on the underlying cause but may include medications, splenectomy, platelet transfusions, or changing medications that are causing the low platelet count.
2. INTRODUCTION
The estimated prevalence of thrombocytopenia in MDS, defined
as a platelet count of <100,000/mcL, ranges from 40% to 65%. A
retrospective review of patients referred to the MD Anderson
Cancer Center identified 1605 of 2410 (67%) patients
with thrombocytopenia at referral. A normal human platelet count
ranges from 150,000 to 450,000 platelets per microliter of
blood. Values outside this range do not necessarily indicate
disease. One common definition of thrombocytopenia requiring
emergency treatment is a platelet count below 50,000 per
microliter
3. DEFINITION
Thrombocytopenia is a condition characterized by abnormally low levels
of platelets , also known as thrombocytes, in the blood. It is the most
common coagulation disorder among intensive care patients and is seen
in 20% of medical patients and a third of surgical patients.
4. CAUSES
Decreased production of platelets
Platelets are produced in your bone marrow. Factors that can decrease platelet production include:
•Leukemia and other cancers
•Some types of anemia
•Viral infections, such as hepatitis C or HIV
•Chemotherapy drugs and radiation therapy
•Heavy alcohol consumption
•Dehydration, Vitamin B12 or folic acid deficiency
•Leukaemia, myelodysplastic syndrome, or aplastic anaemia
•Decreased production of thrombo poietin by the liver in liver failure
•Sepsis, systemic viral or bacterial infection
•Leptospirosis
•Hereditary syndromes[14]
• ACTN1-related thrombocytopenia
• A megakaryocytic thrombocytopenia with radio-ulnar synostosis
• ANKRD26 related thrombocytopenia
5. CAUSES
Increased breakdown of platelets
Abnormally high rates of platelet destruction may be due to immune or nonimmune
conditions, including:[15]
•Immune thrombocytopenic purpura
•Thrombotic thrombocytopenic purpura
•Hemolytic–uremic syndrome
•Disseminated intravascular coagulation
•Paroxysmal nocturnal hemoglobinuria
•Antiphospholipid syndrome
•Systemic lupus erythematosus
•Post-transfusion purpura
•Neonatal alloimmune thrombocytopenia
•Hypersplenism
•Dengue fever
•Gaucher's disease
•Zika virus
6. CAUSES
Some conditions can cause your body to use up or destroy platelets faster than they're produced, leading to a shortage of platelets in your bloodstream.
Examples of such conditions include:
•Pregnancy. Thrombocytopenia caused by pregnancy is usually mild and improves soon after childbirth.
•Immune thrombocytopenia. Autoimmune diseases, such as lupus and rheumatoid arthritis, cause this type. The body's immune system mistakenly attacks
and destroys platelets. If the exact cause of this condition isn't known, it's called idiopathic thrombocytopenic purpura. This type more often affects children.
•Bacteria in the blood. Severe bacterial infections involving the blood (bacteremia) can destroy platelets.
•Thrombotic thrombocytopenic purpura. This is a rare condition that occurs when small blood clots suddenly form throughout your body, using up large
numbers of platelets.
•Hemolytic uremic syndrome. This rare disorder causes a sharp drop in platelets, destruction of red blood cells and impairs kidney function.
Medication-induced
These medications can induce thrombocytopenia through direct myelosuppression:
•Valproic acid
•Methotrexate
•Carboplatin
•Interferon
•Isotretinoin
•Panobinostat
•H2 blockers and proton-pump inhibitors
•. Certain medications can reduce the number of platelets in your blood. Sometimes a drug confuses the immune system and causes it to destroy platelets.
Examples include heparin, quinine, sulfa-containing antibiotics and anticonvulsants.
7. CAUSES
Other causes
•Lab error, possibly due to the anticoagulant EDTA in CBC specimen
tubes;[citation needed] a citrated platelet count is a useful follow-up study
•Snakebite
•Niacin toxicity
•Lyme disease
•Thrombocytapheresis (also called plateletpheresis)[citation needed]
•Niemann–Pick disease
9. SIGNS AND SYMPTOMS
•red, purple, or brown bruises, which are called purpura
•a rash with small red or purple dots called petechiae
•nosebleeds
•bleeding gums
•bleeding from wounds that lasts for a prolonged period or doesn’t stop on its own
•heavy menstrual bleeding
•bleeding from the rectum
•blood in your stool
•blood in your urine
In more serious cases, you may bleed internally. Symptoms of internal bleeding include:
•blood in the urine
•blood in the stool
•bloody or very dark vomit
10. DIAGNOSTIC EVALUATION
Blood tests
To diagnose this condition, your doctor needs to do a complete blood count test. This test looks at the amount of blood cells
in your blood. It’ll tell your doctor if your platelet count is lower than it should be. A typical platelet count will range between
150,000 and 450,000 platelets per mL blood.
Your doctor may also wish to have your blood tested for platelet antibodies. These are proteins that destroy platelets. Platelet
antibodies can be produced as a side effect to certain drugs, such as heparin, or for unknown reasons.
Your doctor may also order blood-clotting tests, which includes partial thromboplastin time and prothrombin time. These tests
simply require a sample of your blood. Certain chemicals will be added to the sample to determine how long it takes your
blood to clot.
Ultrasound
If your doctor suspects that your spleen is enlarged, they may order an ultrasound. This test will use sound waves to make a
picture of your spleen. It can help your doctor determine if your spleen is the proper size.
Bone marrow aspiration and biopsy
If your doctor suspects that there’s a problem in your bone marrow, they may order a bone marrow aspiration. During an
aspiration, your doctor will use a needle to remove a small amount of bone marrow from one of your bones.
A bone marrow biopsy may also be ordered. Your doctor will use a needle to take a sample of your core bone marrow,
usually from the hipbone. It may be performed at the same time as a bone marrow aspiration.
liver enzymes, kidney function, vitamin B12 levels, folic acid levels, erythrocyte sedimentation rate, and peripheral blood
smear. If the cause for the low platelet count remains unclear, a bone marrow biopsy is usually recommended to differentiate
cases of decreased platelet production from cases of peripheral platelet destruction.
11. MANAGEMENT
•blood or platelet transfusions
•changing medications that are causing a low platelet count
•steroids
•immune globulin
•corticosteroids to block platelet antibodies
•drugs that suppress your immune system
•spleen removal surgery
• Lithium carbonate or folate may also be used to stimulate platelet production in
the bone marrow.
• Discontinuation of heparin is critical in a case of heparin-induced
thrombocytopenia (HIT). Beyond that, however, clinicians generally treat to avoid
thrombosis. Treatment may include a direct thrombin inhibitor, such
as lepirudin or argatroban. Other blood thinners sometimes used in this setting
include bivalirudin and fondaparinux. Platelet transfusions are not routinely used
to treat HIT because thrombosis, not bleeding, is the primary problem. Warfarin is
not recommended until platelets have normalized.
