Hyperviscosity in the Small-for-Gestational Age Infant

Abstract

Small-for-gestational age infants are prone to hyperviscosity but the precise incidence is unknown. A prospective survey was conducted on 4,974 consecutive livebirths for hyperviscosity in small-for-gestational age infants. Small-for-gestational age is defined as birth weight below the 10th percentile of the intrauterine growth curve and signs of malnutrition and hyperviscosity as venous blood viscosity (measured by a microviscometer) above the 2 SD of the norm. 79 infants were identified as small-for-gestational age. Of these, 14 were hyperviscous and 65 were normoviscous. The venous hematocrit range from 61 to 70% in hyperviscous and 37 to 62% for normoviscous. A predefined symptom complex referrable to cardiovascular, respiratory, gastrointestinal, and central nervous systems were assessed by an unbiased observer; 57% of hyperviscous and 25% of normal viscous infants were symptomatic (p < 0.05 by χ²). The data indicate that the hyperviscosity syndrome occurs in 17.7% of small-for-gestational age infants; venous hematocrit (64%) is predictive of hyperviscosity, and that in spite of a positive correlation between symptom complex and hyperviscosity, there is a lack of specificity for the clinical manifestation of this neonatal complication.