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In 2008, a sharp increase of the number of children diagnosed with urinary calculi was observed in China, 9433 children were diagnosed as having melamine-induced urinary calculi at outpatient clinic in Beijing Children's Hospital. This study examined the therapeutic efficacy of potassium sodium hydrogen citrate (PSHC) used to treat melamine-induced urinary stones in Chinese children who consumed melamine-containing infant formula.Seventy-two infants and children (average age (18.2 +/- 7.7) months) who were diagnosed with urinary calculi were randomly divided into three treatment groups using the SAS Plan program. Group 1 was given a low dose (1 g/d) of PSHC, group 2 was given high dose of PSHC (2 g/d) and group 3 was given no PSHC (control group). The dose of drug was adjusted according to the baseline urinary pH. This study analyzed the influence of the dose of PSHC, the age of patients, stone size and position, and urinary pH on the level of efficacy of PSHC (cured, effectively treated or not cured).After 1 - 6 months of therapy, 19 patients from group 1, five patients from group 2 and six patients from group 3 were cured. Five patients from group 1, five patients from group 2 and four patients from group 3 were effectively treated. There were significant differences in therapeutic efficacy between the two treatment doses after 3 and 6 months as measured by the increase in the successful expulsion rate and time of melamine-induced urinary calculi. After 6 months the mean time of expulsion of urinary calculi in groups 1 and 2 was significantly shorter than in the control group.PSHC can significantly increase the successful expulsion rate and time of melamine-induced urinary calculi. The therapeutic efficacy is affected by PSHC dose, treatment duration, calculi position, and urinary pH. There is no relationship between the therapeutic efficacy and the stone size or patient age.

Infants in some areas of China developed urinary lithiasis after being fed with powdered milk that was tainted with melamine in 2008 and very small proportion of the infants developed acute renal failure caused by urinary tract calculus obstruction. The aim of this article was to summarize clinical characteristics, diagnosis and treatment of infants with urinary calculus and acute renal failure developed after being fed with melamine tainted formula milk.Data of infant patients with urinary calculus and acute renal failure due to melamine tainted formula milk admitted to the Beijing Children's Hospital Affiliated to the Capital Medical University and the Xuzhou Children's Hospital in 2008 were used to analyze the epidemiological characteristics, clinical manifestations, imaging features as well as effects of 4 types of therapies.All the 34 infants with urinary calculus were complicated with acute renal failure, their blood urea nitrogen (BUN) was (24.1+/-8.2) mmol/L and creatinine (Cr) was (384.2+/-201.2) micromol/L. The chemical analysis on the urinary calculus sampled from 15 of the infants showed that the calculus contained melamine and acidum uricum. The time needed for the four types of therapies for returning Cr to normal was (3.5+/-1.9) days for cystoscopy group, (2.7+/-1.1) days for lithotomy group, (3.8+/-2.3) days for dialysis group, and (2.7+/-1.6) days for medical treatment group, which had no statistically significant difference (P=0.508). Renal failure of all the 34 infants was relieved within 1 to 7 days, averaging (3.00+/-1.78) days.Melamine tainted formula milk may cause urinary calculus and obstructive acute renal failure. It is suggested that firstly the patients with urinary calculus complicated with acute renal failure should be treated with dialysis or medication to correct electrolyte disturbance, in particular hyperkalemia, and then relieve the obstruction with available medical and surgical methods as soon as possible. It was observed that the short-term prognosis was satisfactory.

Intake of melamine can cause renal and ureteral lithiasis in infants and children. The present study aimed to understand the value of ultrasonography in the diagnosis of renal and ureteral lithiasis in infants and young children caused by melamine, and the characteristics of ultrasonograms of melamine-associated calculi.Ultrasonographic examination on the urinary system was performed for 28 332 children who ingested milk powder that was possibly tainted with melamine; 395 of the children were diagnosed by ultrasonography as having urinary calculus, and 231 cases had lump-like calculi and 164 cases had sand gravel-like calculi. The features of the calculi, the sites of obstruction and the status of hydronephrosis and hydroureterosis were analyzed. Ultrasonographic reexamination was performed for 116 patients and the findings were compared with those of the first ultrasonography, and the short-term expulsion of the calculi was evaluated.Most of the 395 patients with urinary lithiasis, except for those who developed renal failure, had no symptoms. The whole profile of the calculi could be seen in most of the cases, because the echogenicity of the calculi with no sharp or absent acoustical shadowing, was weaker as compared with those from calcium-containing calculi. Comet tail sign could be seen behind the echogenicity of single gravel calculus. The rate of diagnostic consistency of ureteral lithiasis between the ultrasound and the results of clinical observation (including stones expelled spontaneously or after cystoscopic intervention) in 51 cases for 76 ureters was 100%. Percutaneous renal biopsy was performed for one case, and histopathological examination showed flocculent, fine strip-like, ellipse and circular deeply stained sand gravel-like material in the renal tubules, and the circular calculi were found to be attached to the walls of the tubules. Chemical analysis of the calculi expelled from 12 cases showed that the main contents of the calculi were uric acid and melamine. Short-term ultrasound reexamination in 116 patients showed that gravel-like calculi disappeared in 80.4% of the cases; in 26 non-hospitalized cases who had lump-like calculi without hydronephrosis or hydroureterosis, none of the lump-like calculi were expelled.The ultrasonographic findings of urinary calculi in children caused by ingestion of melamine-tainted milk powder have a certain features as compared to the calculi containing calcium. Careful ultrasound examination can avoid missed diagnoses of ureteral calculi. Most of the gravel-like calculi can be expelled within a short period of term, while lump-like calculi can hardly be expelled. Ultrasonography is an accurate and reliable method of diagnosis of urinary calculus caused by melamine intake in children and it can be used as diagnostic method of choice although abdominal X-ray plain film can also visualize some of larger calculi.