To investigate the relationship between hyperbilirubinemia and kidney injury in prematures.

A total of 20 prematures with hyperbilirubinemia(as jaundice group) and 15 prematures without jaundice(as control group), who were hospitalized in First People's Hospital of Yibin from March to September 2015, were chosen as study objects. Prematures in jaundice group were further divided into two subgroups: mild jaundice subgroup (n=9) and severe jaundice subgroup (n=11) according to the concentration of total serum bilirubin(TSB) on admission. Peripheral vein blood and urine of all subjects were collected to detect the concentration of TSB, the contents of serum cystatin C, urine microalbumin(mAlb), α₁-microglobulin(α₁-MG) and β₂-microglobulin(β₂-MG). Statistically compared the differences of contents of serum cystatin C and three above-mentioned urinary microprotein between jaundice group and control group, as well as compared the differences of gestational age, birth weight, TSB concentration, day-age of admission, course of disease and the first appearance time of jaundice among prematures with different types of kidney injury. Besides, correlation analysis among various clinical observational indicators were also done. The study protocol was approved by the Ethical Review Board of Investigation in Human Being of First People's Hospital of Yibin. Informed consent was obtained from the parents of each participant. There were no significant differences between jaundice group and control group in gender constituent ratio, gestational age, birth weight and day-age of admission(P>0.05).

①Content levels of mild and severe jaundice subgroup in urinary mAlb[(13.3±7.8) mg/L, (15.1±11.9) mg/L], urinary α₁-MG[(21.2±12.9) mg/L, (15.6±11.5) mg/L] and urinary β₂-MG [(5.6±3.7) mg/L, (5.3±3.8) mg/L] were higher than those in control group[(6.8±2.3) mg/L, (8.0±2.5) mg/L, (1.3±1.0)mg/L], respectively, and the differences were statistically significant(P<0.05). But, there were no significant differences between mild and severe jaundice subgroups in three above-mentioned urinary microproteins (P>0.05). There were no significant differences among mild jaundice subgroup, severe jaundice subgroup and control group in serum cystatin C(P>0.05). ②There were no significant differences among prematures with simple renal tubule injury, mixed kidney injury and no kidney injury in gestational age, birth weight and TSB concentration(P>0.05). The day-age of admission, course of disease and the first appearance time of jaundice of prematures with simple renal tubule injury [(4.1±3.1) d, (1.3±0.8) d, (2.9±2.3) d] were smaller, shorter and earlier than those of prematures with no kidney injury[(14.6±8.2) d, (6.2±3.8) d, (8.4±4.9) d], respectively. The first appearance time of jaundice of prematures with mixed kidney injury[(3.8±2.2) d] was earlier than that of prematures with no kidney injury. Furthermore, both the day-age of admission and course of disease of prematures with simple renal tubule injury were smaller and shorter than those of prematures with mixed kidney injury[(9.8±6.6) d, (6.0±5.5) d]. And all above-mentioned differences were statistically significant(P<0.05). ③There were positive correlation between urinary mAlb and urinary α₁-MG(r=0.822), between urinary mAlb and urinary β₂-MG(r=0.769), between urinary α₁-MG and urinary β₂-MG(r=0.660) in jaundice group(P<0.001). There were negative correlation between urinary α₁-MG or urinary β₂-MG with the first appearance time of jaundice in jaundice group(r=-0.534, -0.508; P<0.05).

Hyperbilirubinemia could induce kidney injury in prematures. The types of kidney injury maybe related to day-age of admission, course of disease and the first appearance time of jaundice. Joint detection of three above-mentioned urinary microproteins could be served as early diagnosis indicators for kidney injury associated with hyperbilirubinemia in prematures.