**Author details**

Pankaj Abrol

**1.7. Hemolytic uremic syndrome**

4 Thrombocytopenia

Pneumococci-associated HUS.

**1.9. Other causes**

**1.8. Kasabach-Merritt syndrome**

It is a classical example of community-acquired acute kidney injury in children. Clinical features are common to TTP but are seen usually in young children, whereas TTP is disease of adults (rarely in adolescents). History of enteritis due to toxin producing *Escherichia coli* and *Shigella dysenteriae* precedes renal involvement. Pneumonia causing Pneumococci can also cause HUS. As diagnosis is usually clinical, renal biopsy is rarely needed. Anemia is initially mild but progresses. Platelet count is in the range of 20,000–100,000/μL. Coombs test is usually positive. Renal insufficiency is variable. It can progress to renal failure. With early diagnosis and prompt care, mortality is <5%, another 5% become dialysis dependent, and 30% may have persistent renal insufficiency in diarrhea-associated HUS. Mortality can be >20% in

Thrombocytopenia is associated with giant hemangioma of infancy. Hemangioma usually solitary may be present over extremities, neck or trunk. Sometimes hemangioma is retroperitoneal. It usually presents in the initial weeks of life, increases in size, and then regresses. Platelet count may be very low with the evidence of DIC. Mortality is 40%. Surgical removal is effective but sometimes not possible. Radiation therapy, vascular ligation/embolization, glucocorticoid therapy, interferon α, vincristine and propranolol are other alternatives.

Infections like systemic bacterial and fungal infections, acute viral infections (e.g., infectious mononucleosis, dengue, and HIV), immunization with live virus vaccines like MMR, hemophagocytic lymphohistiocytosis, malaria, etc., and procedures such as ECMO, hemodialysis, apheresis, liver transplant, etc., can also be associated with thrombocytopenia by increasing their destruction. Dengue is frequently associated with thrombocytopenia. It occurs because of decreased production as well as increased peripheral destruction. Platelet dysfunction is also associated. Drugs like heparin, quinidine, antibiotics like rifampicin and vancomycin also cause thrombocytopenia. Platelets get trapped in enlarged spleen in splenomegaly, por-

Patients having thrombocytopenia due to the decreased platelet production are more likely to have severe bleeding than those having low platelet count due to the increased platelet

**A. Hereditary disorders:** Examples are congenital amegakaryocytic thrombocytopenia, thrombocytopenia absent radius (TAR) syndrome, Fanconi anemia, Bernard-Soulier syndrome, May-Hegglin anomaly, Gray platelet syndrome, and Wiskott-Aldrich syndrome etc.

**B. Acquired disorders:** This includes megaloblastic anemia (folic acid and vitamin B12 deficiency), aplastic anemia, myelodysplastic syndrome, sepsis, cytotoxic chemotherapy

tal hypertension, Gaucher disease, etc., and cause low platelet count.

**1.10. Thrombocytopenia caused by impaired platelet production**

destruction. Common causes of decreased production are:

Address all correspondence to: abrolpankaj1@gmail.com

Department of Pediatrics, Pediatric Hematologist Oncologist, SGT Medical College Hospital and Research Institute, Gurgaon, Haryana, India
