Hyponatremia Identified as Kidney Stone Risk Factor
Studies also link kidney stone development to osteoporosis and proton pump inhibitor use.
CHICAGO—Hyponatremia, osteoporosis, and proton pump inhibitor use emerged as risk factors for kidney stones in separate studies presented at the American Society of Nephrology's 2016 Kidney Week meeting.
The hyponatremia finding is based on a case-control study led by Naoto Tominaga, MD, PhD, of Georgetown University Medical Center in Washington, D.C. Using the electronic health records of 3.2 million unique patients in the MedStar Health system, Dr Tominaga's team identified 21,232 patients with kidney stones (cases) and a like number of controls (no kidney stones) matched by age, sex, and race. The study population had a mean age of 44 years; 48.4% of patients were female and 61% were Caucasian. The mean follow-up was 1345 days. The risk of kidney stones increased for all hyponatremia categories. Kidney stone patients had 10% increased odds of prior hyponatremia, 1.4 times increased odds of chronic hyponatremia, 2.3 times increased odds of recent hyponatremia, and 5.2 times increased odds of chronic and recent hyponatremia compared with controls.
A link between hyponatremia and kidney stone risk is plausible, Dr Tominaga said, noting that hyponatremia is associated with an increased risk for osteoporosis, and the latter is associated with kidney stone development.
In a separate study of 60,740 participants in the Nurses' Health Study II (3402 with osteoporosis and 57,338 without), Megan Prochaska, MD, a fellow at Brigham and Women's Hospital in Boston, and colleagues found that osteoporosis was associated with a significant 39% increased risk of kidney stones compared with individuals who did not have low bone density in multivariate analysis. Osteoporosis also was associated with higher 24-hour urinary calcium excretion.
In addition, participants with osteoporosis who were on a bisphosphonate had a significant 34% lower risk of developing a kidney stone compared with participants with osteoporosis who had not been on a bisphosphonate.
The new findings might support use of a lower threshold for consideration of bisphosphonate use in patients with lower bone density as a strategy for reducing their kidney stone risk, Dr Prochaska said.
Lastly, Pietro Manuel Ferraro, MD, PhD, of the Catholic University of the Sacred Heart in Rome, Italy, and colleagues found that proton pump inhibitor (PPI) use was associated with a significant 12% increased risk of incident kidney stones after adjusting for multiple variables. Use of histamine receptor-2 blockers was associated with a significant 13% increased risk.
Dr Ferraro's group studied 187,330 participants in the Health Professional Follow-up Study and the Nurses' Health Study I and II. A total of 3245 incident symptomatic stone events occurred during a cumulative follow-up of 1,903,725 person-years.
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- Ferraro PM, Curhan GC, Gambaro G, et al. Proton pump inhibitors, histamine receptor-2 blockers and the risk of incident kidney stones. Poster presented at the 2016 Kidney Week meeting in Chicago, Nov. 15-20. Poster FR-PO452.
- Prochaska M, Taylor EN, Curhan GC. Low bone density and bisphosphonates and the association with kidney stones and 24-hour urine calcium excretion. Poster presented at the 2016 Kidney Week meeting in Chicago, Nov. 15-20. Poster FR-PO457.
- Tominaga N, Fernandez S, Mete M, et al. Hyponatremia is associated with increased kidney stones in a large U.S. health system population. Poster presented at the 2016 Kidney Week meeting in Chicago, Nov. 15-20. Poster FR-PO458