الفهرس 
Introduction and Aim of the workOnly 14 pages are availabe for public view
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Abstract
L-arginine is the precursor of nitric oxide (NO) which plays an important role on pulmonary circulation and pulmonary vascular tone. The aim of this work was to estimate plasma L-arginine levels in preterm newborns with respiratory distress syndrome (RDS) and to correlate these levels with the severity of the disease.
This study included 56 preterm newborns. They were divided into two groups: RDS group included 34 preterm newborns with RDS. The control group included 22 preterm newborns who did not develop RDS within the first 6 hours of life. All the studied newborns were subjected to detailed perinatal history, thorough neonatal examination, assessment of Apgar score at 5 minutes, estimation of gestational age using Expanded New Ballard Score, and respiratory system was carefully examined using the Downes´ score for grading of RDS. Laboratory work up included complete blood count, C-reactive protein, arterial blood gases, and estimation of L-arginine levels in plasma by ELISA. Plain chest X-ray was also done for cases of RDS.
Our results showed that:
- Plasma L-arginine levels were significantly lower in the RDS group than in the control group.
- In the RDS group: Sex and mode of delivery had no effect on the levels of plasma L-arginine, plasma levels of L-arginine were significantly higher in newborns whose mothers received antenatal steroids compared to those who did not receive, there were significant positive correlations between plasma L-arginine levels and Apgar score, blood pH, PaO2, and with HCO3. On the other hand, there were significant negative correlations between plasma L-arginine levels and Downes´ score, and with PaCO2. No significant correlation was found between plasma L-arginine levels and gestational age or birth weight, plasma L-arginine levels were significantly lower in newborns who died or developed BPD than in those who were improved.
- The diagnostic value of plasma L-arginine levels in newborns with RDS at a cut-off < 54.25 μmol/ml had a sensitivity of 94.1%, a specificity of 95.5%, a positive predictive value of 97%, a negative predictive value of 91.3%, and an accuracy of 94.6% for prediction of neonatal RDS.
In conclusion, this study demonstrated that preterm newborns with RDS had lower plasma levels of L-arginine compared with non-RDS newborns. L-arginine is a good simple objective marker of RDS severity and prognosis. It is also a reliable marker for diagnosis of RDS. Lastly, its level does not need age, weight, nor sex correction.