Pediatric secondary thrombocythemia

Introduction to children with secondary thrombocytosis The disease is divided into primary and secondary thrombocytopenia, no primary disease thrombocytosis with hemorrhage, called primary thrombocytosis, clinically in certain physiological states (such as after exercise) and different types In acute and chronic diseases, the number of platelets may rise to 400×109/L or more, which is called secondary thrombocytopenia. Thrombocytosis (thrombocytosis) means that the number of platelets exceeds the upper limit of normal values, and the number of platelets often exceeds 1000×109/L (1 million/mm3) or more, up to 14000×109/L (14 million/mm3), and platelet size is abnormal. It is a huge change, and children are rare. Mainly with mucosal bleeding, such as hematuria, gastrointestinal bleeding, nosebleeds, joint bleeding, deep muscle bleeding, bleeding after surgery, etc. basic knowledge The proportion of illness: 0.031% Susceptible people: children Mode of infection: non-infectious Complications: thrombosis

The cause of secondary thrombocytosis in children

(1) Causes of the disease

Disease factors (35%):

Secondary to polycythemia, chronic myeloid leukemia, acute hemorrhage or hemolysis, malignant tumors, myelofibrosis, etc., can also be secondary to iron deficiency anemia, various inflammatory diseases, such as rheumatoid arthritis, acute rheumatism Heat, nodular periarteritis, ulcerative colitis, localized enteritis, tuberculosis, cirrhosis, chronic lung abscess, osteomyelitis, Wegener granulomatosis, sarcoidosis, etc.

In patients with surgically removed spleen or functional spleen loss, platelet counts may increase. Therefore, for patients with such spleen loss, it is normal to have an increase in platelet count.

Drug factors (30%):

Certain drugs can also cause thrombocytosis, such as vinblastine and the antifungal drug miconazole. Infusion of adrenaline can cause platelets from the spleen to mobilize into the blood to produce transient platelet elevation while maintaining the total amount of platelets. After an immunosuppressive drug such as methotrexate-induced thrombocytopenia or a treatment for thrombocytopenia caused by vitamin B12 deficiency, the number of platelets increases within about 10 to 17 days. Transient thrombocytopenia can occur after treatment with prednisone in patients with primary thrombocytopenic purpura.

Acute inflammation (18%):

Caused by the presence of globular cells, Pappenheim bodies, red blood cells and white blood cell debris, or bacteria.

Acute blood loss, iron deficiency anemia, hemolytic anemia.

Recovery after thrombocytopenia (rebound): discontinuation of myelosuppressive drugs, including alcohol, after VitB12 deficiency treatment.

Other factors (10%):

Premature infants, infant VitE deficiency, osteoporosis, heart disease, kidney transplantation, diabetes insipidus, pregnancy, kidney failure.

(two) pathogenesis

Most are due to accelerated platelet production. The cause of secondary thrombocytosis may be the presence of plasma platelet stimulating factor, which causes excessive platelet production. In addition, thrombocytosis in some patients (such as after exercise) is often the result of excessive release of platelets in storage pools such as the spleen and lungs. Since platelet production is regulated by hematopoietic factors, thrombocytosis is at least partially related to the release of factors such as interleukin-1, interleukin-2, interleukin-3, interleukin-6, and interleukin-11. Epinephrine releases platelets from the storage site and causes thrombocytosis. The absence of increased platelet count in the spleen indicates that it is mainly released from the spleen. Exercise also causes platelet release and thrombocytosis, but no spleen also found increased platelet count after exercise. Although there are many platelets, it shows a change in platelet disease, that is, an active thromboplastin-producing disorder, and thus prothrombin consumption is poor. There may also be poor adhesion of platelets, prolonged bleeding time, and positive beam arm test.

Prevention of secondary thrombocytopenia in children

Clinically, if there is unexplained bleeding, it is necessary to see a doctor in time and find out the disease early after treatment. If it is the influence of other external factors, look for the cause and avoid it.

Pediatric secondary thrombocytopenia complications Complications thrombosis

Significant thrombocytosis can cause thrombosis or bleeding tendency, generally lighter.

Hemorrhage and thrombotic complications occur less frequently than primary thrombocytosis, mainly due to complications of the primary disease. After removing the cause, the platelets can gradually return to normal and the course of disease is short.

Symptoms of secondary thrombocytosis in children Common symptoms Thrombocytopenia with mucosal mucosal hemorrhage, hematuria, hemorrhage, muscle bleeding, gastrointestinal bleeding

The number of platelets in secondary thrombocytosis is generally not more than 600 × 109 / L (600,000 / mm3), the number of bone marrow megakaryocytes is increased, but the average volume is not increased, but decreased, only with normal megakaryocytes 2 /3, platelet function has no obvious defects, clinically, in addition to the symptoms of primary disease, bleeding and embolism caused by thrombocytosis is less common. Secondary thrombocytosis is often secondary to polycythemia, chronic myeloid leukemia, acute hemorrhage or hemolysis, malignant tumor, myelofibrosis and splenectomy, etc., but also secondary to iron deficiency anemia, various inflammations Sexual diseases such as rheumatoid arthritis, acute rheumatic fever, nodular arteritis, ulcerative colitis, localized enteritis, tuberculosis, cirrhosis, chronic lung abscess, osteomyelitis, Wegener granulomatosis, sarcoidosis, etc. . In addition, certain drugs can also cause thrombocytosis, such as vinblastine and antifungal drugs miconazole.

After splenectomy, platelets 1/3 can be released into the blood circulation from the spleen pool, so see thrombocytosis. It can be recovered in about 2 months without causing embolism and bleeding. Most of the symptoms of secondary thrombocytosis are mild, and the chances of thromboembolism and abnormal bleeding are less than those of idiopathic.

After an immunosuppressive drug such as methotrexate-induced thrombocytopenia or a treatment for thrombocytopenia caused by vitamin B12 deficiency, the number of platelets increases within about 10 to 17 days. Transient thrombocytopenia can occur after treatment with prednisone in patients with primary thrombocytopenic purpura.

Examination of children with secondary thrombocytosis

Blood test

(1) Platelets:

Platelet count: thrombocytosis, generally not more than 600 × 109 / L (600,000 / mm3), but also up to (800 ~ 1000) × 109 / L.

Platelet function: Platelet factor 3 release and bleeding time are often normal. Poor adhesion, prolonged bleeding time, positive beam arm test, etc. Platelet function tests include various inducer-induced platelet aggregation, and platelets respond poorly to adrenaline and collagen aggregation.

Blood smear: There are piles of platelets in the blood, and there are huge platelets.

2. Bone marrow

The megakaryocytes in the bone marrow are enlarged, large, and rich in cytoplasm. Its average volume is reduced to only 2/3 of normal megakaryocytes.

3. White blood cells and neutrophils can be increased.

4. thromboplastin

It shows a change in platelet disease, that is, an active thromboplastin-producing disorder, and thus prothrombin consumption is poor.

5. Serum student test

A small number of serum acid phosphatase, blood potassium, calcium, phosphorus increased.

6. Select imaging angiography and other examinations according to clinical manifestations: routine chest X-ray, B-ultrasound, angiography, CT and other examinations.

7. Select the necessary auxiliary examination based on the primary disease.

Diagnosis and diagnosis of secondary thrombocytosis in children

Diagnostic criteria:

1. Platelet count: increased.

2. Platelet function: normal.

3. Bone marrow: normal.

4. There are primary causes: such as fever, exercise, spleen and so on.

Differential diagnosis

1.5q-syndrome: with refractory large cell anemia, normal or reduced white blood cells, chromosome 5q-, platelets (600 ~ 800) × 109 / L, small megakaryocytes can be seen in the bone marrow.

2. Iron granulocyte anemia: 10% to 30% of children with thrombocytopenia have refractory anemia, bone marrow smear iron staining see ring iron granulocytes increased.

3. Essential thrombocytosis: Primary or idiopathic thrombocytosis is a type of myeloproliferative disorder. Most of the patients are adults, and children are rare. About 5% of children can develop acute leukemia. In primary thrombocytopenia, platelet production does not respond to normal regulatory mechanisms, and there is no evidence of a decrease in megakaryocytes due to thrombocytosis under normal conditions.

Identify the secondary nature of different causes:

Thrombosis caused by adrenaline and muscle exercise: 150% of the basal level within 15 minutes, and returned to the original basal level in about 30 minutes.

After surgery: after 2 to 6 days, it can be raised to 2.5 times normal, and slowly returns to normal after 10 to 16 days.

After splenectomy: the platelet count can rise to 1000 × 109 / L or higher within 1 week, and usually returns to normal within 2 months.

Disease factors: to return to normal after treatment or to control the development of the primary disease.

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