Evaluation of proximal tubular function in preterm infants by urinary α1‐microglobulin

α1‐Microglobulin is a low molecular weight protein that is relatively stable in urine of low pH. There have been few reports on urinary α1‐microglobulin (U‐A1M) excretion in preterm infants. This study was designed to establish the ranges for U‐A1M in clinically stable preterm infants and to investigate changes observed in sick preterm infants. We measured U‐A1M and urinary β2‐microglobulin (U‐B2M) levels at 1, 4, 7, 14, 28 and 90 days after birth in stable preterm infants (Group 1) and sick preterm infants who were depressed at birth and required immediate resuscitation (Group 2). In Group 1 infants, both parameters were high during the first 28 days and appeared to decline thereafter. U‐A1M in Group 2 infants was only significantly increased compared with Group 1 on day 1, as was U‐B2M. On each day of the study, U‐A1M had significant positive correlations with U‐B2M for all the infants studied. The changes of the two parameters observed in Group 1 probably reflect postnatal evolution of proximal tubular function in stable preterm infants. A comparison of groups 1 and 2 shows a high prevalence of acute tubular injury at birth in sick infants and also suggests that U‐A1M as well as U‐B2M may be a sensitive index for detecting acute tubular damage and for following its course in preterm infants.

[1]  R. Dalton,et al.  Measurement of β2-microglobulin, retinol-binding protein, α1-microglobulin and urine protein 1 in healthy children using enzyme-linked immunosorbent assay , 1990 .

[2]  R. D. Da Riol,et al.  Urinary beta-2-microglobulin excretion in prematures with respiratory distress syndrome. , 1990, Child nephrology and urology.

[3]  J. Whicher,et al.  Stability of alpha 1-microglobulin, beta 2-microglobulin and retinol binding protein in urine. , 1989, Clinica chimica acta; international journal of clinical chemistry.

[4]  J. Perlman,et al.  Renal injury in sick newborn infants: a prospective evaluation using urinary beta 2-microglobulin concentrations. , 1988, Pediatrics.

[5]  C. Tohyama,et al.  Urinary α1‐microglobulin as an indicator protein of renal tubular dysfunction caused by environmental cadmium exposure , 1986, Journal of applied toxicology : JAT.

[6]  Y. Asano,et al.  Human α1-Microglobulin and Its Relationship to Renal Function , 1985 .

[7]  R. Chevalier,et al.  Prognostic factors in neonatal acute renal failure. , 1984, Pediatrics.

[8]  P. Gosling,et al.  beta 2-Microglobulin instability in pathological urine. , 1982, Clinical chemistry.

[9]  A. Aperia,et al.  BETA‐2‐MICROGLOBULIN, AN INDICATOR OF RENAL TUBULAR MATURATION AND DYSFUNCTION IN THE NEWBORN , 1979, Acta paediatrica Scandinavica.

[10]  J. Figueiredo,et al.  Renal filtration, transport, and metabolism of low-molecular-weight proteins: a review. , 1979, Kidney international.