Shift work could put people at risk of developing kidney stones, according to researchers who say that these types of occupations should be targeted for lifestyle interventions.
The risk of kidney stones was particularly great for those who worked nights, report by Man He, from Sun Yat-sen University, Guangzhou, China, and colleagues in the Mayo Clinic Proceedings.
It was also greater for younger people and lower with longer durations of shift work, possibly because adjusting and adapting to shift work results in healthier lifestyles that mitigate risk.
Doing only marginal amounts of manual work were also at increased risk, and the researchers suggest that people who are very active may compensate for this with increased fluid intake compared with those are mostly sedentary.
The association between shift work and kidney stone events could be explained by several lifestyle factors including smoking, sleep, fluid intake and body mass index (BMI).
“The findings of He et al. are relevant to the recognition that certain occupations increase the risk of kidney stones, in large part because of insufficient daily intake of fluids as may occur in healthcare workers, teachers, and cab drivers,” summarized Felix Knauf, MD, from the Mayo Clinic, in Rochester, Massachusetts, and Friedrich Luft, MD, from the Max-Delbrück Center for Molecular Medicine in Berlin, comment in an accompanying editorial.
“Such insufficient fluid intake with limited access to bathroom facilities led Goldfarb to coin the term taxi cab syndrome to describe individuals with reduced intake of fluids, sporadic voiding, urinary stasis, and kidney stones.”
Kidney stones affect a tenth of the U.S. population, a prevalence that has nearly tripled over the past 50 years.
Besides the pain that they cause, kidney stones may acutely trigger hematuria, urinary tract infections, sepsis, and acute kidney injury. Kidney stones are also associated with an increased risk of hypertension, cardiovascular diseases, and diabetes.
He et al. studied 226,459 participants of the UK Biobank, who were followed up for a median of 13.7 years. During this time, 2893 participants developed a kidney stone.
After adjusting for potential confounding factors, individuals who did shift work had a 15% increased risk of kidney stone events (hazard ratio=1.15).
These associations were more pronounced among people younger than 50 years and those who never or rarely dealt with heavy manual labor.
The association between shift work and kidney stones could be explained by current smoking, unhealthy sleep duration, unhealthy sedentary time, BMI, and fluid intake.
“Our study also provides evidence for the need to promote healthy lifestyles to decrease kidney stone event incidence among shift workers,” the researchers concluded.
In their editorial, Knauf and Luft added: “Based on the hazard ratio, the risk of kidney stones with shift work may appear relatively modest.
“However, integrated over time, such risks may be appreciable, especially when accompanied by other recognized risks that can be addressed by a few strategies including dietary modification, cessation of smoking, regular exercise, weight reduction, adequate amounts of nondisturbed sleep, and a copious daily intake of fluids.”
