Stone Composition Among First-Time Symptomatic Kidney Stone Formers in the Community

Abstract

Objective To determine the variation in kidney stone composition and its relationship to risk factors and recurrence among first-time stone formers in the general population. Patients and Methods Medical records were manually reviewed and validated for symptomatic kidney stone episodes among Olmsted County, Minnesota residents from January 1, 1984 to December 31, 2012. Clinical and laboratory characteristics and the risk of symptomatic recurrence were compared between stone compositions. Results There were 2961 validated first-time symptomatic kidney stone formers. Stone composition analysis was obtained in 1508 (51%) at the first episode. Stone formers were divided into the following mutually exclusive groups: any brushite (0.9%), any struvite (0.9%), any uric acid (4.8%), majority calcium oxalate (76%) or majority hydroxyapatite (18%). Stone composition varied with clinical characteristics. A multivariable model had a 69% probability of correctly estimating stone composition, but assuming calcium oxalate monohydrate stone was correct 65% of the time. Symptomatic recurrence at 10 years was approximately 50% for brushite, struvite, and uric acid, but approximately 30% for calcium oxalate and hydroxyapatite stones (P<.001). Recurrence was similar across different proportions of calcium oxalate and hydroxyapatite (P-trend=.10). However, among calcium oxalate stones, 10-year recurrence rate ranged from 38% for 100% calcium oxalate dihydrate to 26% for 100% calcium oxalate monohydrate (P-trend=.007). Conclusion Calcium stones are more common (94% of stone formers) than has been previously reported. While clinical and laboratory factors associate with the stone composition, they are of limited utility for estimating stone composition. Rarer stone compositions are more likely to recur.

Relative Supersaturation of 24-Hour Urine and Likelihood of Kidney Stones

“…Given that CaOx is the most common stone type 8,9 and that most first time stones are CaOx, 10 it is likely that most stones in our study were CaOx. Furthermore, in a validation study of stone formers in these cohorts using medical records, 77% of NHS I, 79% of NHS II, and 85% of HPFS stones were at least 50% calcium stones.…”

“…7 For this present study, we do not have stone composition reports for most participants, though it is expected that the majority of stones were CaOx. 8–11 Although it is likely that less than 10% of stones were 100% UA 10,11 , we analyzed UA supersaturation for this study for completeness, but given the low percentage, these results should be interpreted with caution.…”

Pathogenesis of calcium oxalate urinary stone disease: species comparison of humans, dogs, and cats

“…Calcium oxalate kidney stones are more common in men [2, 3], although this gender gap is declining as kidney stones are being diagnosed more often in women [10]. Higher ambient temperature and sunlight indices are independently related to stone prevalence, indicating that geography and environment play a role in kidney stone risk [23].…”

“…The most common type of kidney stone is composed of calcium oxalate [2, 3] (Table 1). Calcium oxalate stones are often recurrent, with a 10 year recurrence rate of 30% in first time stone formers [2]. The relationship of calcium oxalate kidney stones to important co-morbidities such as chronic kidney disease and metabolic syndrome is currently unclear.…”

Kidney Function After the First Kidney Stone Event

“…This may be due to the older age of stone formers who present with uric acid stones compared to other stone types. 17 It is worth noting, however, that prior studies have suggested that uric acid stones are disproportionately associated with abnormal kidney function or CKD. 2,18–20 In a recent study, uric acid stones were associated with more collecting duct plugs than calcium oxalate stones and collecting duct plugs may contribute to kidney dysfunction.…”