Kidney stones in a Mediterranean population from the south of Spain

Kidney stones have become increasingly prevalent in the developed countries over the past 100 years. The incidence of urolithiasis in a population depends on the geographical area, racial distribution, socio-economic status and dietary habits. During the past decades, these factors have changed affecting the incidence and also the chemical composition of calculi; nowadays in our region, the most common stones composition is calcium oxalate. The identification of the calculi composition enables superior treatment, lower (decreased) cost and a better quality of life for the patients.

We analyzed the composition and the evolution of all of the cases concerning calculi received at Biochemical Clinical Analysis Laboratory from 2007 to 2010, using Interferometry with Fourier transformation (FTIR). The relationship between composition, gender and age was studied for an aleatory group in 2010 (n=657, 431 men and 226 women).

The stone composition obtained was mixtures 24.7% and only one component 75.3%. Calcium oxalate monohydrate (COM) 41.5%, calcium oxalate dihydrate (COD) 7.6%, anhydrous uric acid (AUA) 12.4%, uric acid dehydrate (UAD) 6.7%, urates 1.4%, carbonate-apatite (CA) 2.9%, and others 2.8%. The male to female ratio was 1.9 and the largest number of stones was found in patients between the ages of 40 and 49, for both men and women.

The most common composition (relative percentage) was COM, mixtures and AUA. Presence of calculi is more common in men than in women with the exception of carbonate apatite stones. Stones follow a Gaussian distribution throughout the lifetime of a patient, with particular incidence in those between 40 to 49 years old.