Related Experiment Videos
Normal urinary calcium/creatinine ratios in African-American and Caucasian children
N P So1, A V Osorio, S D Simon
1Section of Pediatric Nephrology, The Children's Mercy Hospital, University of Missouri at Kansas City, 64108, USA.
Insights
Establishing normal urine calcium/creatinine ratio (UCa/Cr) reference values is crucial for pediatric hypercalciuria screening. This study found age and ethnicity significantly impact UCa/Cr, with no strong link to urine sodium/potassium ratio in healthy children.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Biochemistry
Background:
- The random urine calcium/creatinine ratio (UCa/Cr) is a practical tool for screening hypercalciuria.
- Established reference values for pediatric UCa/Cr are lacking globally, with no prior studies on young African-American (AA) children.
- Previous research suggested a link between elevated UCa/Cr and a high urine sodium/potassium ratio (UNa/K).
Purpose of the Study:
- To establish age- and race-specific normal random UCa/Cr values in the pediatric population of Metropolitan Kansas City.
- To investigate potential racial differences in UCa/Cr between Caucasian (CS) and AA children.
- To determine the relationship between UCa/Cr and UNa/K in healthy children.
Main Methods:
- 368 healthy children were divided into four age groups (<7 months, 8-18 months, 19 months-6 years, 7-16 years) and subdivided by race (AA and CS).
- Random urine specimens were analyzed for calcium, sodium, potassium, and creatinine.
- Statistical analysis was performed to determine median UCa/Cr values, 95th percentiles, and correlations between UCa/Cr, UNa/K, and age.
Main Results:
- Median UCa/Cr values showed a strong inverse relationship with age in both AA and CS children.
- UCa/Cr values were consistently higher in CS children compared to AA children across all age groups.
- A weak correlation was observed between UCa/Cr and UNa/K (r²=0.00005 for AA, r²=0.02 for CS), but a strong linear correlation existed between UNa/K and age.
Conclusions:
- Child's age, ethnicity, and geographic location are critical factors when assessing UCa/Cr ratio.
- This study establishes new reference ranges for UCa/Cr in pediatric populations, considering age and ethnicity.
- Contrary to prior reports, no significant relationship between UCa/Cr and UNa/K was found in healthy children.
Abstract:
A random urine calcium/creatinine ratio (UCa/Cr) is of practical use in screening for hypercalciuria. However, due to worldwide variations, reference values for the pediatric population are not yet well established. Furthermore, no study has been conducted to establish normal UCa/Cr values in young African-American (AA) children. It has also been previously reported that an elevated UCa/Cr is related to a high urine Na/K ratio (UNa/K). The objectives of the present study were: (1) to set normal values of random UCa/Cr by age and race in the pediatric population of Metropolitan Kansas City, (2) to identify potential racial differences in UCa/Cr between Caucasian (CS) and AA children, and (3) to determine the relationship between UCa/Cr and UNa/K in healthy children. A total of 368 healthy children of both genders were enrolled in the study. They were divided into four age groups as follows: (1) <7 months, (2) 8-18 months, (3) 19 months to 6 years, and (4) 7-16 years. Each group was subdivided into AA and CS. A non-fasting random urine specimen from each subject was analyzed for Ca, Na, K and creatinine. The median UCa/Cr values for AA were: (1) 0.13, (2) 0.09, (3) 0.06, and (4) 0.04 and for CS they were (1) 0.26, (2) 0.11, (3) 0.10, and (4) 0.09. The data showed a strong inverse relationship between UCa/Cr and age, the youngest children demonstrating the highest UCa/Cr. In each age group, UCa/Cr in CS exceeded the corresponding value in AA. The age-dependent 95th percentiles of UCa/Cr values for CS were (1) 0.70, (2) 0.50, (3) 0.28, and (4) 0.20 and for AA they were (1) 0.38 and (3) 0.24. Due to outliers, the 95th percentile could not be established for the other two AA subgroups. The relationship between UCa/Cr and UNa/K was found to be extremely weak in both AA (r2=0.00005) and CS (r2=0.02). On the other hand, a strong linear correlation was observed between UNa/K and age (CS r2=0.23, P<0.001, AA r2=0.19, P<0.001), explaining in part the lack of correlation between UNa/K and UCa/Cr. We conclude that the child's age, ethnicity and geographic location should be taken into consideration when assessing UCa/Cr ratio. Contrary to what has previously been reported in hypercalciuric children, no significant relationship was found between UCa/Cr and UNa/K in healthy children.