Bone Mineral Density Screening May Benefit Kidney Stone Patients

Bone mineral density (BMD) screening may be warranted in patients with kidney disease, a U.S. database study suggests.

"The increased risk of fracture in patients with kidney stones remains underappreciated," Dr. Calyani Ganesan of Stanford University told Reuters Health by email. "In some patients with kidney stones, dysregulated calcium balance may be present - i.e., calcium is resorbed from bone and excreted into the urine - which can lead to osteoporosis and the formation of calcium stones. Early detection and treatment of osteoporosis could lead to fewer fractures in (these) patients."

As reported in the Journal of Bone and Mineral Research, Dr. Ganesan and colleagues analyzed data on more than 530,000 patients (mean age, 63; about 93% men; 77% White) in the U.S. Veterans Health Administration database from 2007-2015.

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Overall, 19% of those with kidney stone disease also had a non-hip fracture; 6.1% had osteoporosis and 2.1%, a hip fracture. However, only 5% of patients with kidney stone disease completed a 24-hour determination of urine calcium excretion, and 4.5% completed a 24-hour urine citrate measurement.

Among patients with no prior history of osteoporosis or BMD assessment, 9.1% (85%, men) were screened with DXA after their kidney stone diagnosis and 20% of those were subsequently diagnosed with osteoporosis; 19%, with non-hip fracture; and 2.4% with hip fracture.

In multivariable models, type 2 diabetes (odds ratio, 1.07), metastatic cancer (OR, 1.15), enteric disease (ulcerative colitis, Crohn's disease, or celiac disease; OR, 1.19), hypogonadism (OR, 1.22), and primary hyperparathyroidism (OR, 1.59) were associated with higher odds of receiving an osteoporosis or fracture diagnosis after a kidney stone disease diagnosis.

No association was found between osteoporosis and 24-hour calcium excretion; however, 24-hour urine citrate excretion was associated with both osteoporosis and fractures.

The authors conclude, "Our findings provide support for wider use of bone mineral density screening in patients with kidney stone disease, including middle-aged and older men, a group less well recognized as at risk for osteoporosis or fractures."

Dr. Ganesan added, "Our next goal is to identify which patients with kidney stones are at highest risk for fracture and to determine the effects of anti-osteoporosis medications on kidney stone recurrence."

Nephrologist Dr. Mary Ellen Dean, a professor at Touro College of Osteopathic Medicine in Harlem, New York, commented in an email to Reuters Health. "Screening for osteoporosis in men with nephrolithiasis remains particularly challenging. This is potentially due to financial issues - i.e., insurance barriers, reimbursement - (and) lack of clear recommendations for caregivers."

"Considering the significant mortality - with rates for men much higher than for women -and morbidity associated with hip fractures alone, this study supports the need to strongly consider the use of screening tools at a much lower threshold...This seems to be a reasonable long-term strategy to consider in a disease with such devastating consequences."

That said, she added, "There were problems with this study, such as discrepancies in 24-hour urine calcium and lack of relationship to increased fracture risk. These data do not correlate with many other studies. However, the low number of participants who completed the 24-hour urine may account for the finding."

—Marilynn Larkin

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