NEONATAL POLYCYTHEMIA CAUSES

Causes:
• Increased fetal erythropoiesis secondary to fetal hypoxia
o Placental insufficiency can be secondary to preeclampsia, eclampsia, primary renovascular disease, chronic or recurrent abruptio placenta, cyanotic congenital heart disease, postdate pregnancy, maternal smoking, or intrauterine growth restriction (IUGR).
o Endocrine abnormalities secondary to increased oxygen consumption resulting in fetal hypoxia may be due to congenital thyrotoxicosis, congenital adrenal hyperplasia, Beckwith-Wiedemann syndrome, or being the infant of a diabetic mother (IDM).
o Genetics disorders (eg, trisomy 13, trisomy 18, trisomy 21) also may cause in utero hypoxia.

• Hypertransfusion
o Delayed cord clamping allows for an increased blood volume to be delivered to the infant. When cord clamping is delayed more than 3 minutes after birth, blood volume increases 30%.
o Gravity also may be a factor because of the position of the delivered infant in relation to the maternal introitus before cord clamping.
o In the event of delayed cord clamping, blood flow to the infant is enhanced by oxytocin.
o Twin-to-twin transfusion syndrome due to a vascular communication occurs in approximately 10% of monozygotic twin pregnancies.
o Maternal-fetal transfusion may occur.
o As a result of intrapartum asphyxia, the direction of blood flow in the umbilical cord tends to be toward the fetus.

• Dehydration may be due to decreased plasma volume in relation to RBC mass.

Lab Studies:
• Along with symptoms attributable to neonatal hyperviscosity, the central venous Hct measurement is used as a surrogate for diagnosing hyperviscosity because it is a readily available.

• Other laboratory tests include measurements of the following:
o Serum glucose and calcium levels: Measure these to determine if the patient has decreased levels that require treatment.
o Bilirubin level: Measure this level in the infant with jaundice and polycythemia because the increased RBC mass leads to an increased load of bilirubin precursors that can result in hyperbilirubinemia.
o Serum sodium level, blood urea nitrogen level, and specific gravity of urine: Measure these values to aid in the diagnosis of dehydration.
o Arterial blood gases (ABG): Consider measuring ABG values to assess oxygenation in the symptomatic infant.
o Platelet count: This count may demonstrate thrombocytopenia if thrombosis or DIC are present.