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Urinary citrate excretion in idiopathic nephrolithiasis
Simmi K Ratan1, V Bhatnagar, D K Mitra
1Department of Pediatric Surgery, All India Institute of Medical Sciences, New Delhi, India.
Insights
Children with kidney stones have lower urinary citrate levels, especially males and older females. This suggests citrate deficiency is a key factor in pediatric nephrolithiasis, particularly in endemic regions.
Area of Science:
- Pediatric Nephrology
- Urology
- Biochemistry
Background:
- Nephrolithiasis (kidney stones) is a growing concern in children.
- Urinary citrate plays a crucial role in inhibiting stone formation.
- Understanding citrate levels in pediatric stone disease is vital for diagnosis and management.
Purpose of the Study:
- To compare urinary citrate excretion in children with nephrolithiasis and healthy controls.
- To investigate the relationship between urinary citrate levels and stone composition in pediatric patients.
Main Methods:
- Prospective study conducted at a tertiary care center.
- Involved 50 children (under 12 years) with idiopathic urinary calculi and 150 age/weight-matched controls.
- Urinary citrate estimated via colorimetric method in 24-hour urine samples; stone analysis performed.
Main Results:
- Significantly lower 24-hour urinary citrate excretion in stone-forming children compared to controls, particularly in males and older females.
- Hypocitraturia (low citrate) detected in 43% of cases, with higher incidence in calcium phosphate (76%) and calcium oxalate (87%) stones.
- Urinary citrate levels increased with age in both groups, but remained lower in patients.
Conclusions:
- Low urinary citrate is strongly associated with pediatric nephrolithiasis, even without obvious causes.
- Measurement of urinary citrate is recommended for all children diagnosed with kidney stones.
- Findings are particularly relevant for endemic areas with high stone incidence.
Objective:
To determine urinary citrate excretion in children with nephrolithiasis and normal controls.
Design:
Prospective.
Setting:
Tertiary care center in New Delhi.
Methods:
This study was done on 50 children, below the age of 12 years, with idiopathic urinary calculi and 150 age and weight matched controls. The children were divided into 3 groups: Group 1 (1-4 years), Group 2 (5-8 years) and Group 3 (9-12 years). Urinary citrate was estimated in a 24-hour urine sample using colorimetric method. The stones removed from these children were also analysed.
Results:
There was a preponderance of urinary stones in males; the highest incidence being in Group 1. Excretion of citrate in 24-hour urine sample was significantly lower in patients compared to controls, for males in all age groups and for females in Group 3. However, there was no statistically significant difference in the urinary citrate value between males and females in a given age group for either controls or patients. The urinary citrate excretion increased with age in patients and controls, but the levels in patients were lower. Depending upon the constituents, four types of stones were identified, calcium phosphate, calcium oxalate, uric acid and magnesium ammonium phosphate. Nine stones had at least more than one major constituent. Hypocitraturia was detected in 43 percent cases. The incidence was 76 percent for calcium phosphate, 87 percent for calcium oxalate, 40 percent for uric acid stones and 50 percent for magnesium ammonium phosphate.
Conclusion:
This study shows that low urinary citrate is associated with urinary stones in children, especially in endemic areas, in the absence of obvious etiological factors. Urinary citrate excretion should be determined in all children with nephrolithiasis.