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Validity of random urines to quantitate proteinuria in children with human immunodeficiency virus nephropathy
C L Abitbol1, J Strauss, G Zilleruelo
1Department of Pediatrics, University of Miami/Jackson Memorial Medical Center, Florida 33101, USA.
Insights
Assessing proteinuria in children with human immunodeficiency virus (HIV) is challenging. This study validates using random urine protein-to-creatinine ratios (Upr/Ucr) to accurately estimate daily proteinuria in HIV-infected pediatric patients.
Area of Science:
- Pediatric Nephrology
- Infectious Diseases
- Biomarker Validation
Background:
- Accurate proteinuria assessment in pediatric HIV patients is difficult due to timed collection issues and low creatinine excretion.
- Existing methods are limited in very ill children with low muscle mass.
Purpose of the Study:
- To validate the use of random urine specimens for quantifying total protein and creatinine excretion in HIV-positive children.
- To establish a reliable method for proteinuria assessment in this vulnerable population.
Main Methods:
- Developed and tested a mathematical formula to estimate urine volume using random urine samples.
- Validated the formula by comparing calculated and measured urine volumes in HIV-negative and HIV-positive children.
- Analyzed the correlation between measured proteinuria and the urine protein-to-creatinine ratio (Upr/Ucr) in HIV-positive patients.
Main Results:
- The derived formula for estimating urine volume showed high correlation with measured volumes in both HIV-negative and HIV-positive cohorts (r = 0.77 and r = 0.87, respectively).
- A strong significant relationship was found between measured proteinuria and the Upr/Ucr ratio in HIV-positive patients (r = 0.95 linear, r = 0.97 logarithmic).
- The study confirmed that previously accepted Upr/Ucr values (< or = 2.0 normal, > 2.0 nephrotic) are applicable.
Conclusions:
- Random urine protein-to-creatinine ratios can reliably estimate daily proteinuria in HIV-infected pediatric patients.
- This method overcomes limitations of timed collections and low creatinine excretion in this population.
- The findings support the use of Upr/Ucr as a practical and accurate biomarker for monitoring kidney health in pediatric HIV.
Abstract:
Accurate assessment of proteinuria in pediatric patients infected with the human immunodeficiency virus (HIV) is limited by constraints imposed by timed urine collections and low creatinine excretion in very ill patients with low muscle mass. We therefore sought to validate the use of random urine specimens to quantitate total protein and creatinine excretion in a population of 236 HIV-positive children. A mathematical derivation for estimating urine volume (V) was constructed. The accuracy of the final calculation [V = 832 (kL/Ucr)BSA] (where k = constant, L body length, UCr urine creatinine and BSA body surface area) was tested by regression analysis comparing the calculated and measured volume of 31 urines from ambulatory HIV-negative patients. The correlation coefficient was highly significant (r = 0.77, P < or = 0.0001). The relationship was also applied to 23 timed urine specimens from HIV-positive patients with similar significance (r = 0.87, P < 0.0001). A regression analysis of measured proteinuria against the urine protein: creatinine ratio (Upr/Ucr) in these same urines from the HIV-positive patients yielded a significant relationship both in the linear (r = 0.95, y = 0.4x) and the logarithmic regression (r = 0.97, y = x + 0.4). These data support the use of random Upr/Ucr ratios to estimate daily proteinuria in HIV-infected pediatric patients despite low creatinine excretion rates. The previously accepted values continue to apply, with Upr/Ucr < or = 2.0 considered normal and > 2.0 representative of nephrotic proteinuria.