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Variability of urine albumin excretion in normal and diabetic children
1Department of Paediatric Nephrology, Institute of Child Health, London, UK.
Insights
The urine albumin-to-creatinine ratio (UA/UC) is the best method for assessing urine albumin excretion (UAE) in children. Diabetic children show higher UA/UC, with greater individual variability, necessitating at least five tests for reliable results.
Area of Science:
- Pediatric Nephrology
- Diabetology
- Clinical Chemistry
Background:
- Urine albumin excretion (UAE) is a key indicator of kidney health, particularly in diabetic children.
- Variability in UAE measurements poses challenges for accurate assessment and monitoring.
- Standardizing UAE measurement methods is crucial for reliable clinical interpretation.
Purpose of the Study:
- To evaluate the variability of urine albumin excretion (UAE) in normal and diabetic children.
- To determine the optimal method for expressing UAE data for clinical use.
- To compare the variability of UAE measurements between normal and diabetic pediatric populations.
Main Methods:
- Comparison of urine albumin-to-creatinine ratio (UA/UC), urine albumin excretion rate (UAER), and urine albumin concentration (UA) in predicting urine albumin creatinine clearance (CA/CC).
- Analysis of within-individual and between-individual variability of overnight UA/UC using a random effects type 2 nested ANOVA model.
- Inclusion of 171 overnight urine samples from 73 normal children and 406 samples from 119 diabetic children.
Main Results:
- The UA/UC ratio demonstrated the highest correlation (r = 0.95) in predicting CA/CC compared to UAER (r = 0.83) and UA (r = 0.90).
- Geometric mean UA/UC was significantly higher in diabetic children (0.55 mg/mmol) than in normal children (0.33 mg/mmol, P < 0.01).
- Within-individual variance of UA/UC was similar in both groups (0.12), but between-individual variance was substantially greater in diabetics (0.18) than in normals (0.03).
Conclusions:
- The urine albumin-to-creatinine ratio (UA/UC) is the most reliable method for assessing UAE in children.
- Diabetic children exhibit significantly higher UA/UC and greater inter-individual variability in UAE.
- At least five UAE estimations per individual are recommended to achieve reliable mean values due to high within-individual variability.
Abstract:
The variability of urine albumin excretion (UAE) was studied in normal and diabetic children and, in addition, the best method of expressing the data was investigated. In 39 timed overnight urine samples from diabetic children, the urine albumin creatinine clearance ratio (CA/CC) was compared with the urine albumin creatinine concentration ratio (UA/UC), the urine albumin excretion rate (UAER) and the urine albumin concentration (UA). UA/UC predicted CA/CC (r = 0.95) better than either UAER (r = 0.83, P less than 0.02) or UA (r = 0.90), 0.1 greater than P greater than 0.05). The within-individual and the between-individual variability in overnight UA/UC in 171 urine samples from 73 normal children was compared with that of 406 urine samples from 119 diabetic children, using a "random effects type 2 nested analysis of variance" model. Geometric mean (range) UA/UC (mg/mmol) in diabetic children, 0.55 (0.04-6.90), was greater than in normal children, 0.33 (0.05-2.10, P less than 0.01), and 18% of diabetics had a value of UA/UC above the normal range. Within-individual variance was the same in normals (0.12) and diabetics (0.12), but between-individual variance in diabetics (0.18) was much greater than in normals (0.03). These data show that within-individual observations for both normals and diabetics are highly but equally variable. Furthermore, from these data, it is possible to infer that a minimum of five estimations are necessary per individual to estimate the true mean value of urine albumin excretion with reasonable confidence.