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Stone formation and urine composition in calcium stone formers without medical treatment
1Department of Urology, University Hospital, Linköping, Sweden.
Insights
This study found that retrospective stone formation rates in untreated patients correlate with future stone formation, aiding in preliminary treatment evaluation. However, the calcium oxalate supersaturation index did not predict stone formation rates.
Area of Science:
- Nephrology
- Urology
- Biochemistry
Background:
- Kidney stone recurrence is a significant clinical challenge.
- Understanding factors influencing stone formation is crucial for effective management.
- Retrospective analysis of stone formation rates can offer insights into disease progression.
Purpose of the Study:
- To retrospectively estimate the annual rate of stone formation (fSF) in untreated patients.
- To evaluate the correlation between past stone formation and future recurrence.
- To assess the utility of the calcium oxalate supersaturation index (AP(CaOx)) in predicting stone formation.
Main Methods:
- Retrospective analysis of 438 patients attending an out-patient stone clinic.
- Calculation of annual stone formation rate (fSF) based on follow-up and post-diagnosis periods.
- Measurement of urinary parameters including calcium, oxalate, citrate, magnesium, and urine volume.
- Calculation of a standardized AP(CaOx) index for urine supersaturation.
Main Results:
- Only 35% of patients had a reliable retrospective estimate of stone formation rate (fSF).
- A good correspondence was observed between stone formation during follow-up (tT) and post-diagnosis (tA) periods.
- No direct relationship was found between the AP(CaOx) index and fSF, although higher values were seen in patients forming stones within 10 years.
Conclusions:
- Retrospective stone formation rates may be useful for preliminary evaluation of therapeutic response.
- The standardized AP(CaOx) index alone may not be a reliable predictor of stone formation rate in all patients.
- Further research is needed to refine predictive models for kidney stone recurrence.
Abstract:
A retrospective estimate of the annual rate of stone formation (fSF) was obtained in only 154 (35%) of 438 patients without medical treatment at our out-patient stone clinic. Eighty-three of these patients had never been on any prophylactic treatment and were only given advice concerning drinking and dietary habits. There was a high calcium excretion in 46%, high oxalate in 17%, low citrate in 11%, low magnesium in 17%, and increased urate in 16% of the patients. As much as 25% had a 24-hour urine volume below 1,000 ml. There was a good correspondence between stone formation during the follow-up period (tT) and a period of the same length following diagnosis (tA). The mean (+/- SD) tT was 3.2 +/- 1.9 years, with an fSF of 0.19 +/- 0.43. During the tA period fSF was 0.13 +/- 0.31. The number of patients who formed new stones during these periods were 21 and 22, respectively. It is suggested that stone formation during tT and tA advantageously might be used for preliminary evaluation of the therapeutic response. The risk of forming a urine highly supersaturated with calcium oxalate was expressed in terms of a standardized AP(CaOx) index calculated for a 24-hour urine volume of 1,500 ml. There was no relationship between this AP(CaOx) index and fSF. When only those patients were considered who formed new stones during the first 10 years after diagnosis, slightly higher values of the standardized AP(CaOx) index were recorded than in the recurrence-free group.(ABSTRACT TRUNCATED AT 250 WORDS)