Clinical study
Predictive value of kidney stone composition in the detection of metabolic abnormalities

https://doi.org/10.1016/S0002-9343(03)00201-8Get rights and content

Abstract

Purpose

To determine if kidney stone composition can predict the underlying medical diagnosis, and vice versa.

Methods

We studied 1392 patients with kidney stones who underwent a complete ambulatory evaluation and who submitted one or more stones for analysis. We ascertained the associations between medical diagnosis and stone composition.

Results

The most common kidney stones were composed of calcium oxalate (n = 1041 patients [74.8%]), mixed calcium oxalate–calcium apatite (n = 485 [34.8%]), and calcium apatite alone (n = 146 [10.5%]). The most common medical diagnoses were hypocitraturia (n = 616 patients [44.3%]), absorptive hypercalciuria (n = 511 [36.7%]), and hyperuricosuria (n = 395 [28.4%]). Calcium apatite and mixed calcium oxalate–calcium apatite stones were associated with the diagnoses of renal tubular acidosis and primary hyperparathyroidism (odds ratios ≥2), but not with chronic diarrheal syndromes. As the phosphate content of the stone increased from calcium oxalate to mixed calcium oxalate–calcium apatite, and finally to calcium apatite, the percentage of patients with renal tubular acidosis increased from 5% (57/1041) to 39% (57/146), and those with primary hyperparathyroidism increased from 2% (26/1041) to 10% (14/146). Calcium oxalate stones were associated with chronic diarrheal syndromes, but not with renal tubular acidosis. Pure and mixed uric acid stones were strongly associated with a gouty diathesis, and vice versa. Chronic diarrheal syndromes and uric acid stones were associated with one another, and brushite stones were associated with renal tubular acidosis. As expected, there was a very strong association between infection stones and infection, and between cystine stones and cystinuria.

Conclusion

Stone composition has some predictive value in diagnosing medical conditions, and vice versa, especially for noncalcareous stones.

Section snippets

Patient data

Kidney stones were obtained from 1392 patients who underwent complete ambulatory evaluation 5, 7. This diagnostic protocol allows differentiation of different causes of kidney stones, based mainly on identification of abnormal urinary risk factors, believed to be either metabolic or environmental in origin (6). Patients collected the stones within 3 years of evaluation, mostly during the preceding year, at which time they had not been undergoing regular medical treatment for nephrolithiasis.

Association of medical diagnoses with stone composition

Calcium oxalate stones were the most common, followed by mixed calcium oxalate–calcium apatite, calcium apatite, uric acid, mixed uric acid–calcium oxalate, infection stones, brushite, cystine, and ammonium urate (Table 1).

Discussion

From our registry of patients with nephrolithiasis who underwent an ambulatory diagnostic evaluation, stone analyses and medical diagnoses were available in 1392 patients. Our results confirmed the generally recognized importance of stone composition of noncalcareous stones in detecting medical diagnosis 1, 2, including the association of uric acid stones with gouty diathesis (13) and chronic diarrheal syndromes (15), two conditions characterized by a low urinary pH, in which uric acid is

Acknowledgements

The authors wish to thank Roy Peterson and Vicki Lucido for duplicate data entry from patients’ research charts to the computer database in our “stone registry.”

Cited by (0)

This work was supported by NIH grants P01-DK20543 and M01-RR00633, and by institutional funds.

View full text