[Acute retinpathia praematurorum. Is plasma prorenin level of prognostic value?]

In patients with diabetes mellitus an elevated level of plasma prorenin (PP) may be associated with proliferative diabetic retinopathy. Although retinopathy of prematurity (ROP) is also characterized by retinal vasoproliferation, no study on PP in ROP appears to have been carried out. This study investigated PP prospectively in preterm infants with high risk of ROP.

In 304 preterm infants (gestational age 24-36 weeks, mean +/- SD 29.8 +/- 2.6 weeks; birth weight 570-1750 g, 1180 +/- 294 g) PP was examined prospectively between 3 and 14 weeks postnatally. Renin and total renin (after cryoactivation) were determined by radioimmunoassay. Total renin minus renin is the PP level; PP was correlated with the presence of ROP, stage of ROP, gestational age, birth weight, and postnatal age.

There was no significant difference between mean PP in 112 preterm infants with ROP (682 +/- 666 ng/l) and that in 192 preterm infants without ROP (622 +/- 454 ng/l). There was no correlation between PP and the stage of ROP, gestational age, or birth weight. Mean PP decreased with increasing postnatal age (postnatal age 3-4 weeks: 906 +/- 587 ng/l; 7-8 weeks: 585 +/- 423 ng/l; 13-14 weeks: 326 +/- 205 ng/l).

This study found no significant difference in PP between preterm infants with and those without ROP. Thus PP is not a valid predictor or indicator of ROP. However, the study showed a hitherto unknown correlation between PP and postnatal age in preterm infants.