Comparison Blood Cortisol Level in Infants with and without Pain in Neonatal Intensive Care Unit: A Preliminary Study

Neonatal pain and stress response are manifested in three behavioral, physiological and chemical forms. Chemical changes in the pain include secretion and release of hormones and substances such as cortisol, insulin, endorphins and catecholamines. The present study aimed to compare the cortisol level in term infants with and without pain. In this pilot study in 2010, 30 infants who were admitted to the neonatal intensive care unit in Baqiyatallah hospital, divided into two 15-participant groups, with and without pain groups. Thereafter, the blood cortisol level was measured during the painful procedure of blood sampling. Pain or lack of pain was determined through Neonatal Infant Pain Scale (NIPS). Analyzing the data was done by using Mann-Whitney U test and Spearman coefficient correlation and SPSS17 software. Results indicated that cortisol level in both groups had no significant statistical difference (p>0.05); but, there was a significant and direct association between NIPS scores and cortisol level in all participants (p<0.05; r= 0.337). According to the obtained results, it seems that blood cortisol is not a reliable scale to evaluate the pain. However, it should be noted that, measuring the cortisol level and identifying its association and changes with pain, the time of blood sampling, attention to secretion rhythm of this hormone in 24 hours and infants’ age and their physica conditions should be highly considered.