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. 2023 Mar 22;11:1148946. doi: 10.3389/fped.2023.1148946

Table 3.

Laboratory markers of chronic pain and stress in preterm infants.

Marker Extremely preterm infants, n = 19 Very preterm infants, n = 72 Moderate preterm infants, n = 49 Kruskal–Wallis test Р
Dopamine in urine, pg/ml 136.10
(111.80; 163.90)
121.80
(91.43; 165.20)
159.55
(112.50; 238.90)
H = 3.44; p = 0.179 p1–2 = 1.000
p1–3 = 1.000
p2–3 = 0.216
β-endorphin in urine, pg/ml 26.48
(14.23; 44.60)
32.80
(21.99; 50.95)
23.80
(18.94; 37.81)
H = 2.06; p = 0.357 p1–2 = 1.000
p1–3 = 1.000
p2–3 = 0.594
Serotonin in urine, ng/ml 22.71
(14.77; 26.73)
24.03
(17.55; 32.08)
18.75
(14.26; 36.31)
H = 0.68; p = 0.712 p1–2 = 1.000
p1–3 = 1.000
p2–3 = 1.000
Cortisol in saliva, μg/dl 0.734
(0.187; 2.010)
0.325
(0.161; 0.801)
0.246
(0.111; 0.585)
H = 6.44; p = 0.040* p1–2 = 0.142
p1–3 = 0.033*
p2–3 = 0.986
Cortisol in urine, ng/ml 48.35
(37.34; 109.50)
35.44
(18.97; 63.58)
26.68
(16.19; 42.26)
H = 7.26; p = 0.026* p1–−2 = 0.094
p1–3 = 0.021*
p2–3 = 0.824
Oxytocin in urine, pg/ml 39.09
(30.55; 52.52)
39.96
(28.78; 62.50)
34.14
(22.35; 61.19)
H = 0.20; p = 0.904 p1–2 = 1.000
p1–3 = 1.000
p2–3 = 1.000

*Statistically significant results.