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Importance of citrate and the calcium : citrate ratio in patients with calcium renal lithiasis and severe lithogenesis

Miguel Angel Arrabal-Polo*, Miguel Arrabal-Martin*, Salvador Arias-Santiago**^†, Juan Garrido-Gomez^‡, Antonio PoyatosAndujar^§ and Armando Zuluaga-Gomez**

Department of Urology, San Cecilio University Hospital, **Department of Medicine, Baza Hospital, ^†Department of Medicine, University of Granada, and ^‡Departments of Traumatology and ^§Biochemistry, San Cecilio University Hospital, Granada, Spain

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OBJECTIVE

• To analyse the importance of urinary citrate and the urinary calcium : citrate ratio in patients with calcium renal lithiasis and severe lithogenesis compared with a control group of patients without lithiasis.

MATERIAL AND METHODS

• A cross-sectional study of 115 patients in eastern Andalusia, Spain was conducted.

• The patients were divided into two groups: Group A: 56 patients aged 25 – 60 years without calcium renal lithiasis; Group B: 59 patients aged 25 – 60 years, presenting with calcium renal lithiasis and severe lithogenesis.

• The citrate levels and the calcium : citrate ratio in the patients’ urine and the relationship of these two factors to lithiasic activity were analysed and compared.

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 than in Group A (P = 0.001) and the calcium : citrate ratio was higher in Group B than in Group A (P = 0.005).

• The results suggest that a patient urinary calcium : citrate ratio > 0.25 indicates severe lithogenesis (with a sensitivity of 89% and a speciﬁcity of 57%).

• After linear regression analysis, we found that the urinary citrate level is an independent factor associated with the changes in bone densitometry T-score values of patients.

CONCLUSIONS

• 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 severe lithogenesis when this ratio is > 0.25.