Melamine-related urinary stones in 195 infants and young children: clinical features within 2 years of follow-up

The Therapeutic Effect of Catechin on Nephrolithiasis Induced by Co-Exposure to Melamine and Cyanuric Acid in Sprague-Dawley Rats

This study aimed to assess the therapeutic efficacy of catechin against experimentally induced kidney stones resulting from co-exposure to melamine (MEL) and cyanuric acid (CYA) in male Sprague-Dawley rats. To induce nephrolithiasis, a combination of MEL and CYA (1:1 ratio, each at a dose of 31.5 mg/kg bw/day) was administered to the rats for 28 consecutive days. After nephrolithiasis was successfully induced, the rats were randomly divided into two groups: a treatment group and a sham group. The treatment group was given a daily oral dose of 50 mg/kg of catechin for 28 days, while the sham group received no intervention. Urine and blood samples were collected throughout the treatment period, and kidney samples were taken on day 28. Our findings demonstrated that treatment with catechin significantly reduced crystal deposition and pathological damage in the rats from nephrolithiasis. Additionally, renal injury markers were significantly decreased in the treatment group compared to the sham group. These findings suggest that catechin has potential therapeutic benefits in treating nephrolithiasis induced by co-exposure to MEL and CYA.

Animal Models for Studying Stone Disease

Animals have stone disease too. There are several animal models for the research of human stone disease. Rodents are the most frequently used for stone research, although they are not prone to forming crystals in the kidneys. Ethylene glycol (EG), sodium oxalate and l-hydroxyproline are common lithogenic agents. Dogs and pigs were also reported as a study animal for stone disease. However, the breeding costs and body size are too high. The most-used genetic study animal for stone disease was the mouse, but it was high-cost. Calcium oxalate (CaOx) crystals can also be light microscopically observed in the Malphigian tubules of Drosophila melanogaster, induced by adding EG to the food. Genetic studies of flies can be done by cross-breeding, and this has a lower cost than using mice. The fly model also has several advantages, including minimal breeding equipment, the fact that it is easier to reach larger numbers in a short time with flies, that crystals can be observed under microscopy, and that they allow genetic study. We suggest the fly will be an ideal animal model for stone research in the future.

Melamine-associated urinary stone

The devastating contamination of milk formula with Melamine, which caused havoc in China, happened almost eight years ago. Although most patients with melamine-associated urinary stone were given conservative medical treatment, the impact was not completely eliminated. Extensive studies are needed to assess chronic effects in the affected population. In this review, we describe the pathogenesis, pathology, clinical manifestations, management and epidemiology; and the need for longer term follow-up of melamine-associated urinary stones.

The clinical profile and prognosis of Chinese children with melamine-induced kidney disease: a systematic review and meta-analysis

INTRODUCTION

Studies have reported inconsistent results regarding clinical feature and the prognosis status of the affected children in China melamine-contamination event. We summarized available literatures by performing a review and meta-analysis.

METHODS

Statistical pooling was performed using random-effects model; the sources of heterogeneity were explored through subgroup analyses.

RESULTS

Twenty-six studies involving 2164 patients with kidney abnormalities were identified; 94.4% of the patients had urinary calculi and 95.8% of the calculi were < 10 mm in diameter. Of 2040 patients with known types of treatment, 5.6% underwent surgical treatment. The pooled recovery rates at 1, 3, 6, and 12 months after diagnosis or treatment initiation were 67.1%, 76.3%, 85.4%, and 92.3%, respectively; these pooled rates did not differ between the study subgroups stratified by mean age at diagnosis, mean duration of melamine exposure, types of patients (inpatient/outpatient), and treatment types (specific/nonspecific), except that the 1-month recovery rate for studies involving a specific treatment (71.9%) was higher than that for studies involving non-specific treatment (46.2%).

CONCLUSION

The majority of patients had small calculi and could recover without surgical treatment. Kidney abnormalities remained in about 8% of the patients at 12-month followup, indicating a need for longer-term followup.

Four years follow-up of 101 children with melamine-related urinary stones

The melamine-contaminated milk powder incidence occurred in China in 2008. Many studies have been published regarding the epidemiology, clinical symptoms, diagnosis and treatment of melamine-related urinary stones. The objective of this study is to follow-up the effects of melamine-contaminated milk powder consumption on kidney and body growth in children with melamine-related urinary stones 4 years ago. One hundred and one children with melamine-related urinary stones were followed up by urinalysis, renal function tests and urinary ultrasonography. The data of body weight and height, clinical signs and complications were collected. Eighty normal children without the history of consuming melamine-contaminated milk powder were collected as controls. Eighty-one children with melamine-related urinary stones were successfully followed up. Of 45 cases with melamine-related urinary stones treated conservatively after discharge, 34 disappeared completely, 6 dissolved partially, 1 increased in size and 4 did not change at 4 years follow-up. The percentages of under-height and under-weight infants were significantly higher in melamine-related urinary stones group compared to the controls, respectively (p < 0.05). Routine blood, renal and bladder function tests as well as urinalysis were normal in all children. No urological tumors were detected. No noticeable impact of melamine-related urinary stones on kidney and bladder was found at 4 years follow-up. However, whether or not melamine-related urinary stones had effect on body growth needs follow-up in future.

Toxicity of melamine: the public health concern

Melamine contamination in food has resulted in sickness and deaths of human infants, pets, and farm animals in the past decade. The majority of the victims suffered from acute kidney injury, nephrolithiasis, and urolithiasis. Since then, animal studies have revealed the possible target organs of the melamine toxicity and the extent of the adverse effects of the contaminant. State-of-the-art analytical methods have been developed to achieve the "zero tolerance" aim for such economically motivated adulteration. These studies provide in-depth understanding of the melamine toxicity and promising analytical methods, which can help us safeguard our dairy food source.