Definition. Thrombocytopenia is defined as a platelet count <150,000/μL, although a few normal neonates may have counts as low as 100,000/μL in the absence of clinical disease. The best measure of platelet function is the standardized (Ivy) bleeding time (1.5–5.5 min). During the first week of life, bleeding times are shorter than those in adults (<3.5 min).
Incidence. Thrombocytopenia is the most common hematologic abnormality among preterm infants. In healthy term infants the incidence is ~1%. In neonatal intensive care unit (NICU) patients, the incidence is as high as 35%; in low birthweight preterm infants, it is 15–20%; and in extremely low birthweight infants, it is 73%. Approximately 25% of the cases are severe (<50,000/μL); 75% are considered mild to severe.
Normal platelets. The rate of platelet production and turnover in neonates is similar to that of older children and adults. The platelet life span is 7–10 days, and the mean platelet count is >200,000/μL. Platelet counts are slightly lower in low birthweight infants, in whom platelet counts <100,000/μL have occasionally been observed in the absence of a clinical disorder. Low platelet counts should nonetheless be investigated in low birthweight infants. Platelet counts vary according to the method of determination. Phase microscopy determinations are generally 25,000–50,000/μL lower than those obtained by direct microscopy.
Etiology of thrombocytopenia
Maternal disorders causing thrombocytopenia in infant:
Chronic intrauterine hypoxia. This is the most frequent cause of thrombocytopenia in preterm neonates in the first 72 h of life. This is seen in cases of placenta insufficiency such as diabetes and pregnancy induced hypertension.
Drug use (eg, heparin, quinine, hydralazine, tolbutamide, and thiazide diuretics).
Infections (eg, TORCH [toxoplasmosis, other infections, rubella, cytomegalovirus, and herpes simplex] infections, bacterial or viral infections).
Disseminated intravascular coagulation (DIC).
Pregnancy-induced hypertension (in particular with HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count).
Antibodies against maternal and fetal platelets (autoimmune thrombocytopenia):
Idiopathic thrombocytopenic purpura (ITP).
Systemic lupus erythematosus.
Gestational or incidental thrombocytopenia.
Antibodies against fetal platelets (isoimmune thrombocytopenia):
Neonatal alloimmune thrombocytopenia (mostly anti-HPA-1a alloantibodies).
Isoimmune thrombocytopenia associated with erythroblastosis fetalis.
Placental disorders causing thrombocytopenia in infant (rare):
Neonatal disorders causing thrombocytopenia:
Decreased platelet production or congenital absence of megakaryocytes
Thrombocytopenia and absent radius (TAR) syndrome.
Trisomies 13, 18, 21 or Turner syndrome.
Inherited metabolic disorders (methylmalonic, propionic, and isovaleric acidemia, ketotic glycinemia).
Congenital amegakaryocytic thrombocytopenia.
Increased platelet destruction
Increased platelet consumption occurs in many sick infants not associated with any specific pathologic state. This form of thrombocytopenia is the most common hemostatic abnormality in the newborn admitted to the NICU. About 20% of newborns admitted to the NICU experience thrombocytopenia; for 20% of those, counts are <50,000/μL. This form of thrombocytopenia, generally present by 2 days of life, reaches a nadir by 4 days and usually recovers to normal by 10 days of life.
Pathologic states associated with increased platelet destruction.
Bacterial and Candida sepsis.
Congenital infections. TORCH infections especially CMV. Neonates with HIV and Enterovirus frequently have thrombocytopenia.
Thrombosis (renal vein, intracardiac, vascular).
Intrauterine growth retardation.
Necrotizing enterocolitis (NEC).
Platelet destruction associated with giant hemangioma (Kasabach-Merritt syndrome).
Drug-induced platelet dysfunction:
Maternal use of aspirin.
Phototherapy-induced metabolic abnormalities.
Fatty acid deficiency.
Inherited thrombasthenia (Glanzmann disease).
Risk factors. Low birthweight, lower gestational age, small for gestational age, growth restriction, hypoxia at birth, umbilical line placement, respiratory assistance, hyperbilirubinemia, phototherapy, prematurity, respiratory distress syndrome, low 5-min Apgar score (<7), sepsis especially by Candida infection, meconium aspiration, NEC, mother with ITP, preterm infants of hypertensive mothers. Risk factors for preterm infants includes growth restriction, lower gestational age at delivery, and low 5-min ...
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessPediatrics Full Site: One-Year Subscription
Connect to the full suite of AccessPediatrics content and resources including 20+ textbooks such as Rudolph’s Pediatrics and The Pediatric Practice series, high-quality procedural videos, images, and animations, interactive board review, an integrated pediatric drug database, and more.
Pay Per View: Timed Access to all of AccessPediatrics
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.