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Nephrocalcinosis is associated with renal tubular acidosis in children with X-linked hypophosphatemia
1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235-9063, USA.
Insights
Nephrocalcinosis, a complication of X-linked hypophosphatemia treatment, is linked to renal tubular acidosis. This study found a high prevalence of acidosis in patients with nephrocalcinosis.
Area of Science:
- Nephrology
- Pediatric Endocrinology
Background:
- X-linked hypophosphatemia (XLH) causes rickets and growth issues.
- Phosphate and vitamin D therapy for XLH can lead to nephrocalcinosis.
- Long-term renal effects of nephrocalcinosis in XLH patients are not well understood.
Purpose of the Study:
- To determine the prevalence of glomerular and tubular disorders in XLH patients with nephrocalcinosis.
Main Methods:
- Compared creatinine clearance and renal tubular acidosis prevalence.
- Studied 19 XLH patients with nephrocalcinosis and 15 XLH patients without nephrocalcinosis.
Main Results:
- 84% of XLH patients with nephrocalcinosis had hyperchloremic metabolic acidosis versus 8% without.
- Patients with nephrocalcinosis showed significantly lower serum bicarbonate levels.
- Creatinine clearance was similar between groups, indicating preserved glomerular function.
Conclusions:
- Nephrocalcinosis is a common complication of XLH therapy.
- Nephrocalcinosis is associated with renal tubular acidosis in XLH patients.
Background:
X-linked hypophosphatemia is characterized clinically by rickets and growth retardation. Therapy of this disorder with phosphate and vitamin D often produces nephrocalcinosis. The long-term effects of nephrocalcinosis on renal function in patients with X-linked hypophosphatemia are unknown. The purpose of this study was to evaluate the prevalence of glomerular and tubular disorders in patients with X-linked hypophosphatemia who developed nephrocalcinosis.
Methods:
The creatinine clearance and the prevalence of renal tubular acidosis were compared in 19 patients with X-linked hypophosphatemia and nephrocalcinosis with 15 patients with X-linked hypophosphatemia without nephrocalcinosis.
Results:
Sixteen of the 19 patients (84%) with nephrocalcinosis had a hyperchloremic metabolic acidosis compared with one of the 13 patients without nephrocalcinosis (P < .01). The serum bicarbonate of patients with nephrocalcinosis was 20.0 +/- 0.7 as compared to 24.5 +/- 0.6 mmol/L in patients without nephrocalcinosis (P < .01). The urinary anion gap was positive in all patients with acidosis (+62.1 +/- 13.3 mmol/L). The creatinine clearance was 125 +/- 6 mL/min/1.73 m2 in patients with nephrocalcinosis and 124 +/- 7 mL/min/1.73 m2 in those without nephrocalcinosis.
Conclusion:
Therapy of X-linked hypophosphatemia is often associated with nephrocalcinosis. Nephrocalcinosis is associated with renal tubular acidosis in patients with X-linked hypophosphatemia.