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Low birth weight and reduced renal volume in Aboriginal children
Insights
Low birth weight is linked to smaller kidney volumes in Aboriginal children. This finding supports the theory that reduced nephron number from poor fetal growth may increase later kidney disease risk.
Area of Science:
- Pediatric Nephrology
- Public Health
- Developmental Origins of Health and Disease
Background:
- Low birth weight is a known risk factor for adult renal disease in Aboriginal populations.
- Reduced nephron endowment due to intrauterine growth restriction is a potential mechanism.
- Early-life kidney volume may reflect nephron number and predict future kidney health.
Purpose of the Study:
- To investigate the association between birth weight and renal volume in Aboriginal children and adolescents.
- To determine if low birth weight is associated with smaller kidney size in this high-risk population.
- To explore the implications for the developmental origins of renal disease.
Main Methods:
- Ultrasound measurement of kidney dimensions in 174 Aboriginal children and adolescents (aged 5-18 years).
- Calculation of kidney volume (KV) using a standard formula.
- Correction of kidney volume for body surface area (corrKV) to account for current body size.
Main Results:
- Mean birth weight was 2.9 kg; 19% were classified as low birth weight (<2.5 kg).
- Combined kidney volume, corrected for body surface area (corrKV), averaged 240 ± 45 mL/1.73 m² and was age-independent.
- Low birth weight children had significantly lower average corrKV (approx. 20 mL less) compared to normal birth weight children, with differences driven by kidney depth.
Conclusions:
- Low birth weight is associated with reduced renal volume in Aboriginal children, independent of current body size.
- This finding supports the hypothesis that intrauterine growth retardation leads to a lower nephron endowment.
- Reduced kidney volume in low birth weight individuals may be a contributing factor to their increased susceptibility to renal disease.
Abstract:
Low birth weight predisposes to renal disease in Aboriginal adults. This could be due to reduced nephron numbers, which might be reflected in lower kidney volumes, at least early in life. In this study we evaluated the association of birth weight with renal volume in 174 children and in adolescents 5 to 18 years old in an Aboriginal community with high rates of renal disease. Their mean birth weight was 2.9 kg, and 19% had been low birth weight (<2.5 kg). Kidney dimensions were measured by ultrasound by a single observer, and kidney volume (KV) was calculated from the formula KV (mL) = length x (depth 1 + depth 2)/2 x 0.523. Combined kidney volume, corrected for body surface area (corrKV), was independent of age and averaged 240 +/- 45 mL/1.73 m(2). The average corrKV was significantly lower (by about 20 mL) in low birth weight children than in those with "normal" birth weight. There was a difference of 32 mL in combined corrKV between children in the lowest versus the highest quintile of birth weight. Disparities in calculated kidney volume were driven more by lower kidney depth than length in low birth weight children. We conclude that low birth weight children have lower renal volumes than children of higher birth weights, after correction for current body size. This conclusion is compatible with the theory that intrauterine growth retardation is associated with reduced nephron endowment. The susceptibility to renal disease associated with low birth weight in this population might be mediated in part through this mechanism.