Investigation of na-citrate co-transporter gene polymorphism in hypocitraturic calcium containing kidney stones

Objective: Following urinary tract infections and prostatic disorders urolithiasis is the third most common disease affecting urinary tract, which is an important public health issue for our country. Although decreased urinary excretion of citrate is an established risk factor for calcium containing kidney stones, whether it is related to genetic abnormalities remains to be defined. In this prospective study Na-citrate co-transporter gene polymorphism was investigated as a part of metabolic evaluation in patients with idiopathic calcium urolithiasis.Material and Method: On an outpatient basis study 56 hypocitraturic and 40 normocitraturic individuals with idiopathic calcium urolithiasis underwent a full metabolic evaluation including serum biochemistry and 24-hour urinary investigations of citrate, calcium, oxalate, magnesium, and uric acid. Also, an investigation of Na-citrate co-transporter gene polymorphism using a real time polimerase chain reaction was performed in all individuals.Results: Both groups were similar in terms of age, height, weight, gender, family history, urinary pH and density, serum biochemistry, and 24-hour urinary excretion of calcium, oxalate, magnesium and uric acid. Na-citrate co-transporter gene mutation was identified in 7.1% of hypocitraturic group, while in %10 of normocitraturic patient group. The difference in the ratio of Na-citrate co-transporter gene mutation between the two groups was found to be statistically insignificant (p=0.618).Conclusions: Our results do not support the role of Na-citrate co-transport gene polymorphism in the etiopathogenesis of hypocitraturia in patients with idiopathic calcium urolithiasis. Limitations of the present study are the lack of both strict diet administration and non inclusion of a real control group. Thus, in order to clarify the role of genetic abnormalities in deficient urinary excretion of citrate further studies should be done with larger samples of patients and normal controls in a more standardised conditions to eliminate environmental effects.Key words: Hypocitraturia, Calcium Urolithiasis, Genetic Mutation, Metabolic Evaluation, Na-citrate Co-transporter Gene