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Divergence between stone composition and urine supersaturation: clinical and laboratory implications
J Lingeman1, R Kahnoski, H Mardis
1Renal Section, University of Chicago, Illinois, USA.
The Journal of Urology
|March 19, 1999
Summary
This study identifies two types of kidney stone formation divergences. Type 1 involves high urine supersaturation without stones, while Type 2 involves stones without high supersaturation, often due to hydration changes.
Area of Science:
- Nephrology
- Urology
- Biochemistry
Background:
- High urine supersaturation typically correlates with kidney stone formation.
- Exceptions to this rule, termed structural divergences, warrant investigation.
Purpose of the Study:
- To investigate exceptions where high urine supersaturation occurs without a corresponding stone phase (Type 1) or a stone phase exists without high supersaturation (Type 2).
- To understand the clinical implications of these divergences in kidney stone disease.
Main Methods:
- Measured urine supersaturation for calcium oxalate, calcium phosphate, and uric acid in 716 patients.
- Assessed other established kidney stone risk factors.
Main Results:
- 14% of patients exhibited Type 2 divergence (stones without high supersaturation), linked to high urine volume and low calcium excretion.
- Type 1 divergence (high supersaturation without stones) was associated with higher calcium excretion and low urine volume, posing no clinical concern.
- Type 1 patients were primarily calcium oxalate stone formers with high supersaturations across multiple stone types.
Conclusions:
- Type 1 divergence likely reflects low urine volume, increasing general supersaturation.
- Type 2 divergence suggests increased urine volume and decreased calcium excretion between stone formation and testing.
- Understanding these divergences aids in personalized kidney stone prevention strategies.