TY - JOUR
T1 - Biochemical profile of idiopathic uric acid nephrolithiasis
AU - Pak, C. Y C
AU - Sakhaee, K.
AU - Peterson, R. D.
AU - Poindexter, J. R.
AU - Frawley, W. H.
N1 - Funding Information:
This work was supported by grants P01-DK20543 and M01-RR00633 from the National Institutes of Health.
PY - 2001
Y1 - 2001
N2 - Background. The objective of this study was to elucidate a biochemical profile of patients with idiopathic uric acid nephrolithiasis, without secondary causes (such as dehydration or diarrhea). Study subjects comprised 56 patients with idiopathic uric acid nephrolithiasis (UA stone group) who underwent a full outpatient evaluation. The control group was composed of 54 with absorptive hypercalciuria and 2 normal subjects, matched with the UA stone group according to age, body mass index, and gender. Methods. Urinary pH and ammonium and serum and urinary uric acid were measured. The fractional excretion of urate was calculated. Results. Compared with the control group, the UA stone group had a significantly higher serum uric acid and significantly lower urinary uric acid, pH (5.34 ± 0.23 vs. 6.17 ± 0.36, P < 0.001), and fractional excretion of urate (0.052 ± 0.028 vs. 0.080 ± 0.029, P < 0.001), but individual values overlapped considerably between the two groups. Discriminant analysis of the relationship between urinary pH and fractional excretion of urate yielded a "discriminant score," which provided a much better separation between the two groups, with a correct classification in 95.5% of subjects. In contrast, urinary ammonium, citrate, sulfate, and potassium did not differ between two groups. Conclusions. In idiopathic uric acid nephrolithiasis, urinary pH and fractional excretion of urate are significantly lower than in control subjects, suggestive of defects in urinary acidification and urate excretion. Since these impairments are believed to be associated with primary gout, the underlying disturbance in idiopathic uric acid nephrolithiasis may be primary gout.
AB - Background. The objective of this study was to elucidate a biochemical profile of patients with idiopathic uric acid nephrolithiasis, without secondary causes (such as dehydration or diarrhea). Study subjects comprised 56 patients with idiopathic uric acid nephrolithiasis (UA stone group) who underwent a full outpatient evaluation. The control group was composed of 54 with absorptive hypercalciuria and 2 normal subjects, matched with the UA stone group according to age, body mass index, and gender. Methods. Urinary pH and ammonium and serum and urinary uric acid were measured. The fractional excretion of urate was calculated. Results. Compared with the control group, the UA stone group had a significantly higher serum uric acid and significantly lower urinary uric acid, pH (5.34 ± 0.23 vs. 6.17 ± 0.36, P < 0.001), and fractional excretion of urate (0.052 ± 0.028 vs. 0.080 ± 0.029, P < 0.001), but individual values overlapped considerably between the two groups. Discriminant analysis of the relationship between urinary pH and fractional excretion of urate yielded a "discriminant score," which provided a much better separation between the two groups, with a correct classification in 95.5% of subjects. In contrast, urinary ammonium, citrate, sulfate, and potassium did not differ between two groups. Conclusions. In idiopathic uric acid nephrolithiasis, urinary pH and fractional excretion of urate are significantly lower than in control subjects, suggestive of defects in urinary acidification and urate excretion. Since these impairments are believed to be associated with primary gout, the underlying disturbance in idiopathic uric acid nephrolithiasis may be primary gout.
KW - Gout
KW - Hypertriglyceridemia
KW - Hyperuricemia
KW - Primary gout
KW - Renal ammoniagenesis
KW - Stone-former
KW - Urate stones
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U2 - 10.1046/j.1523-1755.2001.060002757.x
DO - 10.1046/j.1523-1755.2001.060002757.x
M3 - Article
C2 - 11473659
AN - SCOPUS:0034918222
SN - 0085-2538
VL - 60
SP - 757
EP - 761
JO - Kidney international
JF - Kidney international
IS - 2
ER -