[Clinical and diagnostic significance of microalbuminuria and activity of tubular enzyme N-acetyl-beta-D-glucosaminidase (NAG) determination in patients with hyperuricosuria].

Aim: Development of the approaches to detection of hyperuricosuric stage of purin metabolism derangement and specification of methods for early diagnosis of urate damage to the kidney.
Materials and Methods: The study included 115 young subjects whose parents suffer from gout with renal involvement or isolated urate nephropathy. Each patient was examined clinically with evaluation of family history for gout risk factors. Three times for 9 months measurements were made of uricemia and uricosuria, microalbuminuria and activity of tubular enzyme NAG.
Results: 45 (39.1%) patients had neither disturbances of purin metabolism nor renal affection. 70 (60.9%) patients had hyperuricosuria. In 23 (32.9%) of them microalbuminuria increased to > 20 mg/day, NAG activity to 5 u/l. Chronic tubulointerstitial nephritis was diagnosed in 17 (73.9%) patients. Six patients (26.1%) developed asymptomatic affection of the kidneys. The rest 47 patients had normal levels of microalbuminuria and NAG. There were 3 cases of hyperuricemia with microalbuminuria rising to 160-200 mg/day and further development of urinary syndrome. Hyperuricemia in them was registered at microalbuminuria higher that 160 mg/day.
Conclusion: Microalbuminuria higher than 20 mg/day and NAG activity higher than 5 u/day are important diagnostic indicators of renal affection in hyperuricosuria including asymptomatic one. Microalbuminuria above 160 mg/day gives grounds to discuss the role of morphological changes prior to proteinuria.