[Clinical and metabolic features of renal calculi in adults in regard to age of onset].

Background: In this paper, the clinical and metabolic patterns of nephrolithiasis in different ages of adulthood are studied.

Methods: Eight-hundred patients observed at the Mauriziano Hospital between 1990 and 1995, were classified into 3 groups, on the basis of age at the onset of disease: A: 20 through 39 years; B: 40 through 59; C: 60 years and over.

Results: Calcium-oxalate stones had a lower recurrence in C (19.1%) and B (31.5%) than in A (41.7%). Pure uric acid stones recurred in 18.9% of C, 16.7% of B and 4.3% of A. The prevalence of hypercalciuria was higher in A (50.3%) than in B (35.9%) and C (36%); so did hypocitraturia. Hyperuricuria was lower in A (5%, p < 0.05) than in B (9.4%) and C (10%). Low urine pH (< 5.5) was 13% in A, 21.3% in B, 38% in C. Prevalence of hyperoxaluria was about 14% in all groups. The whole prevalence of secondary forms of stone disease was 13% in A, 12% in B and 30% in C. Differences among groups were mainly due to prevalence of urological abnormalities and urinary tract infection. In patients without metabolic disturbances. urological abnormalities or urinary tract infections altogether, were 4.6% in A; 5.2% in B; 33% in C. Urological approach removed 8% of stones in A, 5.6% in B and 10.2% in C.

Conclusions: Higher morbidity in younger patients could be due to a lower prevalence of easier-passing uric acid stones. The higher occurrence of urological disturbances and struvite stones in the elderly could explain the higher morbidity in this group.