In order to better define criteria for diagnosis and treatment of neonatal polycythemia, 74 neonates with peripheral venous hematocrit levels ≥65% were studied. The hematocrit levels of capillary (Cap Hct), peripheral venous (PV Hct), and umbilical venous (UV Hct) blood were measured. Viscosity of umbilical venous blood (UVη) was determined. Mean ± SE Cap Hct (75 ± 0.5%) was significantly higher than PV Hct (71 ± 1.0%, P < .001) and PV Hct was higher than mean UV Hct (63 ± 0.6%, P < .001). Cap Hct correlated with neither PV Hct nor UV Hct, but PV Hct and UV Hct correlated moderately (r = .54, P < .001). Of the neonates with UV Hct ≥63%, 80% had UVη in excess of 3 SD above the normal mean (in excess of 14.6 cps at shear rate 11.5 sec-1), whereas 94% of the neonates with UV Hct <63% had UVη within normal range. Neonates with hyperviscosity were seen with two or more clinical symptoms more often than their peers with normal viscosity (P < .04). Partial exchange transfusion in 21 neonates reduced mean UV Hct from 61 ± 1.1% to 50 ± 1.0% (P < .001) and mean UVη from 13.0 ± 0.64 cps to 8.6 ± 0.54 cps (P < .001). These data suggest that Cap Hct and PV Hct may be used to screen neonates for polycythemia, but that the final diagnosis and therapeutic decisions should be based on UV Hct or even preferably on UVη. They further suggest that UV Hct ≥63% is strongly indicative of hyperviscosity and should be treated by partial exchange transfusion.
- Received April 25, 1980.
- Accepted September 10, 1980.
- Copyright © 1981 by the American Academy of Pediatrics