Objective: The main concern in neonatal polycythemia is complication development due to hyperviscosity. We aimed
to compare symptoms, clinical and laboratory features, and organ dysfunctions of polycythemic newborns with respect
to gestational age, hematocrit (hct) levels and presence of thrombocytopenia.

Material and Methods: Between January 2013 and December 2016, all hospitalized newborns with a gestational
age of ≥ 34 weeks were retrospectively evaluated and those with a venous hct value exceeding 65% were included.
Exclusion criteria were infections, metabolic diseases and congenital anomalies. Newborns were grouped and compared
according to hct values (65–69.9% vs. ≥70%), gestational age (late preterm vs. term) and thrombocytopenia (present/
absent).

Results: Polycythemia incidence was 7.7% in the study group. The most common symptoms were hypoglycemia
and hyperbilirubinemia, while 35.1% of newborns were asymptomatic. Hypoglycemia, hypocalcemia, and plethora
were significantly more frequent in the severe polycythemia (hct ≥70%) group than in the moderate polycythemia (hct
between 65–69.9%) group (p = 0.027, p = 0.014, p < 0.001, respectively). Hyperbilirubinemia was more common in
late preterm babies than term babies (p = 0.014). Feeding difficulty, convulsion, hypoglycemia, hypocalcemia and liver
function test abnormalities were significantly more common in newborns with thrombocytopenia than those without (p
= 0.002, p = 0.004, p < 0.001, p = 0.022, p = 0.043, respectively).

Conclusion: It should be kept in mind that more than one-third of polycythemic newborns may be asymptomatic. While
the most common symptoms were hypoglycemia and hyperbilirubinemia, liver function tests may also be adversely
affected.

Keywords: Hematocrit, hyperviscosity, late preterm, newborn, thrombocytopenia