Treating the overproduction of one hormone may be a way to help a subset of the millions of Americans who suffer from obstructive sleep apnea, according to a new study.
People with obstructive sleep apnea stop breathing for short periods while they are sleeping, which leads to a poor night’s sleep and debilitating fatigue during the day. Most people with the condition need to use dental devices or CPAP (continuous positive airway pressure) machines to sleep at night.
But researchers at UC San Francisco have found that treating a condition in the adrenal glands causing an excess of aldosterone, a hormone that maintains electrolyte balance and blood pressure, may be an effective way to help people reduce the risk of obstructive sleep apnea.
UCSF endocrine surgeons Insoo Suh, MD, and Quan-Yang Duh, MD, didn’t set out to study sleep apnea. Suh and Duh specialize in the treatment of primary aldosteronism (also known as Conn's syndrome), a disease in which one or both of the adrenal glands overproduce the hormone aldosterone, and were looking into the question of whether this hormone plays a role in obesity. Obesity is a major factor in obstructive sleep apnea, which meant that many of the surgeons’ patients were living with that condition as well.
To his surprise, Suh found that treating patients for excess hormone didn’t help their obesity – but did relieve their sleep apnea.
Suh found himself in cluster of interconnected conditions. “There are multiple bidirectional arrows connecting hypertension, obesity, and obstructive sleep apnea,” says Suh. “Now we’re introducing aldosterone into this equation.”
The results of the initial study led him to look into the literature and see if there was any evidence of an independent relationship between aldosterone and obstructive sleep apnea.
“We found that there were small but intriguing studies that suggested a link,” says Suh. “Given the prevalence of sleep apnea, it is certainly worth looking into further.” Obesity is certainly a primary cause of obstructive sleep apnea, but Suh says the data show there must be other factors at play. “There’s a prevalence of about 5 to10 percent for obstructive sleep apnea across cultures and countries, independent of diet, geography, and developmental status of countries,” he says. “That points to other causes we haven’t identified yet.”
The study’s initial results indicate that aldosterone might be one factor. If he’s right, it could have broad health benefits, helping patients with high blood pressure as well as obstructive sleep apnea.
Until recently, primary aldosteronism was thought to be rather rare, affecting only 1 percent of the population.
“But now, based on bigger population-based studies, we’re able to identify a greater number of patients with risk factors for primary aldosteronism and get them referred to an endocrinologist,” says Suh.
That has led to much greater awareness of primary aldosteronism, and many more diagnoses.
A UCSF study has found that treating patients for an excess of the hormone aldosterone relieved their obstructive sleep apnea, giving a new avenue for treating a subset of the people who have the disorder.
Primary aldosteronism is the leading cause of secondary hypertension in the U.S. Suh estimates that up to 1 in 20 people with hypertension may have aldosteronism. Depending on the source of excess aldosterone, surgery or blood pressure medications that block aldosterone provide very effective treatments.
“One broader health question here is ‘can we identify more cases of aldosteronism by looking at patients with obstructive sleep apnea and high blood pressure?’” says Suh. And if so, is some fraction of high blood pressure and obstructive sleep apnea the result of a very treatable condition?
Suh is quick to caution that his study was preliminary, drawn largely from comparing information in charts and medical records, and arose from a study that wasn’t designed to do a thorough investigation of sleep apnea.
“We’re excited by the results and it’s in a relatively large number of patients with primary aldosteronism,” he says. He’s currently designing future studies that would involve sleep studies and other more explicit measures of sleep apnea, and follow patients through treatment to determine outcomes.
“I suspect we’ll find a compelling link between primary aldosteronism and obstructive sleep apnea,” Suh says. And he hopes that understanding that link will result in identifying more patients with the condition, and help hundreds of thousands of Americans get a better night’s sleep.
ABOUT SLEEP APNEA
Sleep apnea is a disorder in which your breathing is interrupted for periods of 10 seconds or more while you are asleep. These interruptions may occur hundreds of times a night, causing you to gasp for air and disrupting your sleep.
There are two main types of sleep apnea:
Obstructive Sleep Apnea
This is the most common type of sleep apnea. It is characterized by an obstruction or narrowing of the nasal passages and throat during sleep. Patients tend to wake up repeatedly to gasp for air.
Central Sleep Apnea
This type of sleep apnea is believed to be related to a malfunction of the brain's normal signal to breathe. The level of carbon dioxide in the blood rises, which may cause you to wake up.
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