A Japanese study found that those with sleep disordered breathing were four-and-a-half times more likely to have chronic kidney disease compared to those in a control group. These findings led researchers to recommend those who experience sleep disordered breathing to seek kidney screenings.
Although there appears to be a link between obstructive sleep apnea (OSA) and kidney health, there is still no real consensus as to why. One suggestion is that some of the symptoms of OSA, such as higher oxidative stress, lower blood-oxygen levels, and hypertension harm the kidneys.
Another study linked OSA with higher levels of creatinine in the blood, which is a sign of poor kidney function.
Can kidney disease cause OSA?
A 2012 study published in _Chest_recruited 254 individuals with kidney disease at varying levels of severity. Researchers found that sleep apnea become more prevalent as disease severity increased.Twenty-seven percent of patients with a normal estimated glomerular filtration rate (eGFR) were found to have sleep apnea. This increased to 41 percent for those who were not on dialysis but had an eGFR of less than 60, and increased again to 57 percent for those with end-stage renal disease.
Researchers concluded that the nocturnal oxygen deficiency associated with OSA can contribute to the loss of kidney function and also increase cardiovascular risk. Chronic kidney disease is associated with metabolic acidosis — a condition in which too much acid builds up in the body. This condition has been found to increase the risk for developing sleep apnea.
One study found the pharyngeal area to be narrower in those with end stage renal disease compared to those with normal renal function. This is one cause of OSA and may be caused by fluid accumulation.
How to improve kidney health when suffering from OSA
Studies suggest that CPAP treatment may help improve kidney function. One study in particular found that just three months of CPAP therapy lowered creatinine levels and increased kidney filtration rates.
Why does sleep apnea appear to damage the kidneys?
A review published in the _Journal of Clinical Sleep Medicine_concluded that sleep apnea may lead to kidney disease due to:Increased blood pressureRenal oxygen deficiency*Oxidative stressHow to improve OSA symptoms if suffering from kidney diseaseA study published in 2001 found that patients living with end-stage renal disease who switched from hemodialysis three times per week to nocturnal dialysis at home six to seven times per week experienced a significant improvement in OSA symptoms. However, the study was unable to identify the reason behind these results.
A separate study found that continuous ambulatory peritoneal dialysis doubled the prevalence of severe sleep apnea compared to nocturnal peritoneal dialysis.
Prevention is better than cure
Being aware of the risk factors for obstructive sleep apnea and kidney disease can help you avoid these conditions.
Risk factors for obstructive sleep apnea include:
Risk factors for kidney disease include:
If you have been diagnosed with sleep apnea, it may be worth speaking with your doctor about kidney health. Similarly, if you have been diagnosed with kidney disease, it may be a good idea to talk to your doctor about sleep apnea.