For the study, researchers matched30,517 osteoporosis cases to 30,517controls without osteoporosis andmatched 46,256 fragility fracture casesto 46,256 controls without fragilityfracture. Compared with individualswithout hyponatremia, those withchronic hyponatremia had a 4-foldincreased odds of osteoporosis and 4.6-fold increased odds of fragility fracture,according to a report published onlineahead of print in The Journal of ClinicalEndocrinology and Metabolism. Patientswith recent hyponatremia had a 3-foldincreased odds of both osteoporosisand fragility fracture. Patients withboth chronic and recent hyponatremiahad a 12- and 11-fold increased oddsof osteoporosis and fragility fracture,respectively.
The researchers defined recent hyponatremiaas a serum sodium level below135 mmol/L within 30 days before theend of the encounter window; theydefined chronic hyponatremia as atleast 2 consecutive serum sodiummeasurements below 135 mmol/L atleast 1 year apart during the encounterwindow.
Results also showed that lower serumsodium is associated with higher risk.For example, a median level of 130–134mmol/L is associated with a 4.4-foldincreased odds of osteoporosis and a4.5-fold increased odds of fragility fracture,whereas a median level below 130mmol/L is associated with a 6.6-foldand 7.0-fold increased odds of osteoporosisand fragility fracture, respectively.
Women made up 66.3% of the osteoporosiscases and controls and 55.4% ofthe fragility fracture cases and controls.
“This investigation adds to the accumulatingevidence that even mildhyponatremia may have clinical implicationsfor patients risk of osteoporosisand fragility fracture,” the researchers,led by Joseph G. Verbalis, MD, ofGeorgetown University Medical Centerin Washington, D.C., wrote.
Dr. Verbalis’ group noted that theirstudy potentially clarifies and expandsthe findings of the Rotterdam study,which found that hyponatremia atstudy entry was associated with a 1.4-fold increase in nonvertebral fracturesover 7.4 years of follow-up and a 1.8-fold increase in prevalent, but not incident,vertebral or hip fractures.