劉展榮、黃鶴翔、林永明¹

成大醫院 泌尿部¹

Chan-Jung Liu, Ho-Shyan Huang, Yorng-Ming, Lin¹

Department of Urology, Cheng-Kung University Hospital, Tainan, Taiwan¹

 

Purpose: Urinary tract stone analysis has been seen as a historically necessary metric in recognizing the etiology and the further medical or surgical treatment. Pak et al reported that the most common form of kidney stones were calcium oxalate (74.8%), mixed calcium oxalate–calcium apatite (34.8%), calcium phosphate alone (10.5%), uric acid stones (5.8%), infection stones (3.9%), and cystine stones (2.7%). Studies in western countries have reported different pattern of stone variety compositions. Maalouf et al. found that uric acid nephrolithiasis accounts for 8-10 % of all kidney stones in the United States. In Taiwan, Huang et al. reported 9,715 urinary calculi, collected from 1956 to 1999, were analyzed and only 3.2% uric acid stone was found. However, Chou et al. reported up to 7.6% uric acid stones in 1000 South Taiwan patients. The purpose of this study was to survey the distributions of all kinds of stones and the trend of uric acid urolithiasis in patients at NTH and NCKH during the period from 2008 to 2014.

Materials and Methods: We retrospectively reviewed patients who received stone analysis from 2008 to 2011 in NTH and from 2011 to 2014 in NCKH. A total 1257 patients was enrolled. Stone specimen was submitted by patients or collected by endoscopic surgery. Stone analysis was used with a Perkin–Elmer R × 1-FTIR Fourier transform infrared spectrophotometer. Spectra were obtained by KBr disc technique.

Results: Total 685 (54.5%) and 572 (45.5%) patients were included in North Taiwan group and South Taiwan group respectively. The largest stone components (52.3%) were CaOx followed by apatite (29.5%) (Table 1). To compare patients in North and South Taiwan, no significant difference in all kinds of stones but only in Struvite and uric acid stones. Higher percentage of uric acid stones was found in South Taiwan than North Taiwan (12.41% v.s. 9.21%). A total of 135 patients with uric acid stones were older than average (67.2±11.04 v.s. 57.48±14.49, p<0.001). Men to women ratio were 5.75:1. If we divided all patients above and below 49 years old, uric acid stones accounted much more in older group (12.81% v.s. 5.23%, p=0.0001).

Conclusions: In present study, higher incidence of uric acid urolithiasis was found (10.75%), especially in South Taiwan group. Most uric acid stones patients were male and older, which was similar as previous study. Hyperuricosuria, low urine volumes and persistently low urine pH are the three major lithogenic factors for precipitation of uric acid. Diet rich in purine is a possible explaination for high prevalence in formation of uric acid stones.