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

• Published in: BJU international Vol. 111; no. 4; pp. 622 - 627
• Main Authors: Arrabal‐Polo, Miguel Angel, Arrabal‐Martin, Miguel, Arias‐Santiago, Salvador, Garrido‐Gomez, Juan, Poyatos‐Andujar, Antonio, Zuluaga‐Gomez, Armando
• Format: Journal Article
• Language: English
• Published: Oxford Wiley-Blackwell 01.04.2013
• Subjects: Adult; Biological and medical sciences; Biomarkers - analysis; bone; Bone Density; Calcium - metabolism; Calcium - urine; Calculi - chemistry; Citric Acid - metabolism; Citric Acid - urine; Confidence Intervals; Creatinine - urine; Cross-Sectional Studies; Decalcification, Pathologic - physiopathology; Female; Humans; Incidence; Linear Models; lithogenic activity; Logistic Models; Male; Medical sciences; Middle Aged; Multivariate Analysis; Nephrolithiasis - diagnosis; Nephrolithiasis - epidemiology; Nephrolithiasis - urine; Nephrology. Urinary tract diseases; Odds Ratio; Predictive Value of Tests; Prognosis; Risk Assessment; ROC Curve; Severity of Illness Index; Spain; Urinalysis; urinary calcium : citrate ratio; urinary citrate; Urinary lithiasis; Spain; Kidney disease; Human; Urine; Nephrology; Urinary system disease; Calciuria; Calcium; lithogenic activity; Citrate; Inorganic element; urinary calcium: citrate ratio; Biological activity; Urology; Urinary stone; Osteoarticular system; urinary citrate; Renal lithiasis; Ratio; Bone; Severe
• ISSN: 1464-4096; 1464-410X; 1464-410X
• DOI: 10.1111/j.1464-410X.2012.11292.x

What's known on the subject? and What does the study add? Different studies have shown the importance of citrate in the formation of calcium stones. It has further been shown that the states of metabolic acidosis result in an increase in bone resorption and lower urinary citrate levels. Increasing the intake of citrate in these patients can reduce the lithogenic risk and improve bone mineral density (BMD), contributing to control of both diseases. The study shows the importance of citrate in patients with calcium stones and BMD loss. The deficit in citrate excretion is associated with a decrease in bone mineralization and increased β‐crosslaps. A calcium : citrate ratio >0.25 in patients with calcium stones and loss of mineral density may predict severe lithogenic activity. 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.