Endocrine Abstracts

Introduction: One of the factors influencing a predisposition to calcium renal lithiasis is a lack of crystallization inhibitors, the most important of which is citrate. The aim of our study was to analyze the importance of urinary citrate and the urinary calcium/citrate ratio in patients with calcium renal lithiasis and severe lithogenesis in comparison with control group patients without lithiasis.

Methods/Design: We conducted a cross-sectional study of 115 patients in eastern Andalusia (Spain). The patients were divided into two groups: groups A and B. Group A: 56 patients aged 25 to 60 years without calcium renal lithiasis. Group B: 59 patients aged 25 to 60 years presenting with calcium renal lithiasis and severe lithogenesis. We analyzed and compared the citrate levels and the calcium/citrate ratio in the patients’ urine and the relationship of these two factors to lithiasic activity. In addition, we examined the bone mineral density across groups.

Results: In group B, 32.2% of the patients presented with hypocitraturia, compared with 14.3% of the patients in group A (P=0.02). The urinary citrate levels were lower in group B compared to group A (P=0.001), and the calcium/citrate ratio was higher in group B compared to group A (P=0.005). Our results suggest that a patient urine calcium/citrate ratio ≥0.25 indicates serious lithogenesis (sensitivity of 89%, specificity of 57%). After a linear regression analysis, we found that the urinary citrate level is an independent factor associated with changes in bone densitometry T-score values of patients.

Conclusion: Compared to the control group, the patients with severe lithogenesis presented with hypocitraturia, which was associated with lower bone mineral density. The calcium/citrate ratio, which is linearly related to the bone resorption marker β-crossLaps, could be useful in evaluating the risk of serious lithogenesis when its value is exceeds 0.25.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.