Table 5.

Serum and urine uric acid in classic and variant LND

Patient group	Serum uric acid (mg/dl)	Urine uric acid (mg/kg per 24 h)	Urine uric acid/ creatinine ratio
Classic LND	11.7 ± 4.8	42.6 ± 17.3	3.2 ± 1.1
HPRT-related neurological dysfunction	13.0 ± 3.8	33.6 ± 13.1	1.6 ± 0.8
HPRT-related hyperuricaemia	12.4 ± 5.7	23.9 ± 9.8	1.0 ± 0.5

Uric acid measures for 349 classic and 125 variant cases of LND reported in the prior literature. To avoid skewing the results by over-representation of individual samples, multiple values or ranges of values reported for any one case were averaged to give a single value. When multiple values were reported over several years for one case, only the first value was used, since serum uric acid varies according to age and the values could not be averaged. We excluded values from patients who were receiving drugs known to alter uric acid. Statistical comparisons were conducted via the Kruskal–Wallis test for non-parametric data, which revealed significant group differences for 24 h urinary uric acid (P = 0.003) and uric acid/creatinine ratios (P < 0.001) but not for serum uric acid (P = 0.13).