Sir,A recent publication on urinary pH, melamine, and kidney stone formation is very interesting.[1] Lu et al. reported “an association of gender and urinary pH with melamine-associated kidney stone formation risk”.[1] This can be useful epidemiological information. However, some facts of medical biochemistry should be discussed. The reported pH in this publication is not clear. Only a value of < and ≥6.5 can be read. Indeed, the correlation can be directly assessed by the correlation study between the exact urine pH value and solubility. Based on chemical structure, melamine is a base and increases solubility in acidic conditions (very good if pH is lower than 4).[2] However, it is a fact that the range of human urine pH is not wide (4.5–8); hence, the solubility of melamine might be affected slightly.