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Urinary alpha 1-microglobulin as an index of proximal tubular function in early infancy
H Tsukahara1, M Hiraoka, M Kuriyama
1Department of Paediatrics, Fukui Medical School, Japan.
Insights
Urinary alpha 1-microglobulin (U-A1M) is a sensitive marker for acute proximal tubular damage in newborns. Levels are high initially, then decline, indicating recovery and serving as a key index of infant kidney function.
Area of Science:
- Neonatal physiology
- Renal medicine
- Biomarker discovery
Background:
- Urinary alpha 1-microglobulin (U-A1M) is a low molecular weight protein filtered by the glomerulus and reabsorbed by proximal tubules.
- Assessing proximal tubular function in neonates is crucial for understanding kidney health and detecting early damage.
Purpose of the Study:
- To evaluate U-A1M as a marker of proximal tubular function in healthy term infants.
- To investigate the correlation of U-A1M with urinary beta 2-microglobulin (U-B2M) and serum A1M.
- To assess U-A1M's utility in identifying acute tubular damage in sick neonates.
Main Methods:
- Longitudinal measurement of U-A1M in healthy term infants from day 1 to 180 of life.
- Comparison of U-A1M levels in healthy, intrauterine growth-retarded, and sick neonates requiring resuscitation.
- Correlation analysis with U-B2M and serum A1M.
Main Results:
- U-A1M levels were elevated in the first 14 days of life, decreasing thereafter.
- U-A1M correlated significantly with U-B2M throughout the study.
- Sick neonates requiring resuscitation showed elevated U-A1M and U-B2M on days 1-7, which normalized subsequently.
- Stable infants with intrauterine growth retardation did not show elevated U-A1M on days 1-7.
Conclusions:
- U-A1M is a sensitive indicator of acute proximal tubular damage and recovery in neonates.
- U-A1M serves as a valuable index for assessing proximal tubular function in early infancy.
- The findings support the use of U-A1M in neonatal nephrology for monitoring kidney health.
Abstract:
Urinary alpha 1-microglobulin (U-A1M) was measured in healthy term infants on days 1, 4, 7, 14, 28, 90 and 180 of life. U-A1M was high until day 14 and declined thereafter. It was significantly correlated with urinary beta 2-microglobulin (U-B2M) throughout the study, but not with serum A1M on days 1 or 7. Similar to U-B2M, U-A1M in the clinically stable term infants with intrauterine growth retardation (n = 4-7) was not elevated on days 1-7. In the sick infants who needed immediate resuscitation at birth (n = 4-8), U-A1M was well as U-B2M was high on days 1-7 and then decreased to normal levels, suggesting that U-A1M can be used as a sensitive marker of acute proximal tubular damage and its recovery. These observations indicate that U-A1M is a useful index of proximal tubular function in early infancy.