title: Renal injury in sick newborn infants: a prospective evaluation using urinary beta 2-microglobulin concentrations.
abstract: Urinary concentrations of beta 2-microglobulin and creatinine were measured serially in 140 sick infants, of whom 109 were asphyxiated, and in 35 healthy preterm and term infants. First voided urines and samples from days 3 and 7 postpartum were studied. Urinary beta 2-microglobulin concentrations in healthy infants averaged 1.34 +/- 1.34 mg/L (mean +/- SD) in first voided specimens and 1.32 +/- 0.98 mg/L in day 3 samples; the calculated upper limit of normal (95% confidence limit) was 4.00 mg/L. Elevated values (those exceeding the 95% confidence limit) occurred most often in the sick asphyxiated patients (56%); the first voided sample value in these patients was 10.0 +/- 10.4 mg/L. The equivalent value in the sick nonasphyxiated infants was 8.32 +/- 7.27 mg/L. Values were significantly and persistently elevated in the sick infants on days 3 and 7. Factoring beta 2-microglobulin levels by urinary creatinine concentration did not affect the significance of the findings. The increased urinary beta 2-microglobulin levels were not (1) related to gestational age; low beta 2-microglobulin values occurred at all gestational ages for both healthy and sick infants; (2) a consequence of urine flow rate; urinary beta 2-microglobulin did not correlate with urinary creatinine concentration or with urine to plasma creatinine ratio; and (3) a consequence of increased production of beta 2-microglobulin; urinary and serum beta 2-microglobulin values did not correlate (r = .03). Thus, we propose that the elevated levels of urinary beta 2-microglobulin in the sick infants were the consequence of tubular injury. This was associated with hematuria but not with a high incidence of azotemia or oliguria.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis, MO.
authors.forename: E D
authors.initials: ED
authors.lastname: Tack
authors.forename: J M
authors.initials: JM
authors.lastname: Perlman
authors.forename: A M
authors.initials: AM
authors.lastname: Robson
mesh_terms: D001238:Asphyxia Neonatorum / Q000097:blood / Q000652:urine*; D003404:Creatinine / Q000097:blood; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007668:Kidney / Q000293:injuries*; D011188:Potassium / Q000652:urine; D012964:Sodium / Q000652:urine; D001613:beta 2-Microglobulin / Q000652:urine*
chemical_list: D001613:beta 2-Microglobulin; D012964:Sodium; D003404:Creatinine; D011188:Potassium