OBJECTIVETo establish a high-performance liquid chromatography-mass spectrometry (LC/MS)-based method for efficient determination of melamine in urinary calculi in children taking melamine-contaminated formula milk powder.

METHODSLC/MS was employed to determine the contents of melamine in urinary calculi surgically removed from 17 children with a history of taking melamine-contaminated milk powder and in 4 samples of uric acid stone from adults. The positive ionization mode of electro-spray ionization source was used, and the limit of melamine determination was 0.1 mg/kg.

RESULTSNo melamine was detected in the 4 uric acid stone samples from adults. Melamine was detected in 4 samples of urinary calculi from the 17 children, with the concentration ranging from 0.8 to 64 mg/lkg.

CONCLUSIONLC/MS is simple and effective for detecting melamine in urinary calculi, which is helpful to the treatment and follow-up.

Chromatography, High Pressure Liquid ; methods ; Dairy Products ; adverse effects ; Female ; Food Contamination ; Humans ; Infant ; Male ; Mass Spectrometry ; methods ; Triazines ; analysis ; Urinary Calculi ; chemically induced ; chemistry

Objective　To analyze the clinical indications,efficacy and safety of Chinese minimally invasive percutaneous nephrolithotomy (MPCNL) in treating upper urinary calculi based on our experience.Methods　From June 1992 to September 2010,a total of 10,452 patients (6060 males and 4392 females)with a mean age of (47.6 ± 13.7) years (7 months-93 years) received MPCNL in our center.The mean stone burden was (777.4 ± 740.3) mm2 (20 - 4 080 mm2 ).The data of stone burden,operative techniques,operating time,stone-free rate,major complication,hospital stay and stone composition were investigated.　Results　Of the 10 452 cases,11 801 procedures were performed on 10 876 (5493 left and 5383right) renal units,including 10 102 first stage procedures,1604 secondary procedures,86 third procedures and 9 fourth procedures.There were 11 830 tracts established,including 373 (3.15％ ) tracts of 14 F,7867 (66.50％) tracts of 16 F and 3590 (30.35％) tracts of 18 F.There were 1207 (10.20％),9174(77.55％) and 1449 (12.25％) punctures located in upper,middle and lower pole,respectively.956(8.79％) renal units were managed with multiple tracts,which including 2 tracts in 846 (7.78％) units,3tracts in 85 (0.78％) units,4 tracts in 18 (0.17％) units and 5 tracts in 7 (0.06％) units.Pneumatic lithotripsy was used in 8563 (72.56％) procedures,Holmium:YAG laser lithotripsy was used in 2981(25.26％)　procedures and Pneumatic lithotripsy + Holmium: YAG laser lithotripsy was used in 257(2.18％) procedures.762 (7.29％) cases needed ESWL to clean the stone after MPCNL.The average operating time was ( 101.3 ± 44.2) min ( 10 -240 min).The stone-free rate of MPCNL was 89.9％,which increased to 93％ by adjunctive ESWL.And the mean hospital stay was ( 13.2 ± 6.4) days (2 - 72 days).The major complications happened on 321 (3.07％) cases,including 294 (2.81％ ) cases of blood transfusion,12 (0.11％ ) cases of sepsis,2 (0.02％) cases of renal abscess,9 (0.09％) cases of pleura injury,2 (0.02％) cases of colon injury and 2 (0.02％) cases of death.53 (0.51％) cases needed selective renal arterial embolization to achieve hemostasis.The main stone compositions were analyzed in 4345 cases.Calcium oxalate,calcium phosphate,magnesium ammonium phosphate,uric acid,ammonium urate,carbapatite and cystin were 91.74％,90.33％,14.91％,17.77％,4.83％,8.47％ and 0.51％,respectively. Conclusions　MPCNL is an effective and safe treatment option for all kinds of upper urinary calculi in patients at all ages with a high stone free rate and low major complication rate.