Decreased urinary citrate excretion in type 1a glycogen storage disease.
OBJECTIVE
To quantify urinary citrate and calcium excretion and systemic acid-base status in patients with type 1a glycogen storage disease (GSD1a) and to investigate their relationship to renal complications.


METHODS
Fifteen patients (7 male and 8 female; age range, 3--28 years) were studied during annual evaluations of metabolic control. All were treated with intermittent doses of uncooked cornstarch. Hourly blood sampling and a 24-hour urine collection were obtained while subjects followed their usual home dietary regimen.


RESULTS
All but the youngest subject had low levels of citrate excretion (mean 2.4 +/- 1.8 mg/kg/d; 129 +/- 21 mg citrate/g creatinine). Normally, urinary citrate excretion increases with age; however, in patients with GSD1a, a strong inverse exponential relationship was found between age and citrate excretion (r = -0.84, P <.0001). Urinary citrate excretion was unrelated to markers of metabolic control. Hypercalciuria occurred in 9 of 15 patients (mean urinary calcium/creatinine ratio, 0.27 +/- 0.15) and was also inversely correlated with age (r = -0.62, P =.001).


CONCLUSIONS
Hypocitraturia that worsens with age occurs in metabolically compensated patients with GSD1a. The combination of low citrate excretion and hypercalciuria appears to be important in the pathogenesis of nephrocalcinosis and nephrolithiasis. Citrate supplementation may be beneficial in preventing or ameliorating nephrocalcinosis and the development of urinary calculi in GSD1a.
Weinstein
D A
DA
Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Somers
M J
MJ
Wolfsdorf
J I
JI
D000293:Adolescent; D000328:Adult; D002118:Calcium / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D019343:Citric Acid / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate; D005953:Glycogen Storage Disease Type I / Q000150:complications / Q000652:urine*; D006801:Humans; D007669:Kidney Calculi / Q000209:etiology* / Q000652:urine; D016018:Least-Squares Analysis; D008297:Male; D009397:Nephrocalcinosis / Q000209:etiology* / Q000652:urine
D019343:Citric Acid; D002118:Calcium