Suspect OSA in patients with nocturia

The severity of sleep apnea has been correlated with frequency of nighttime bathroom visits.

Suspect OSA in patients with nocturia
Suspect OSA in patients with nocturia

It is not uncommon for urologists to refer patients who get up multiple times during the night to urinate to see a primary care provider when no other significant abnormalities have been identified.

In these cases, the obvious diseases associated with nocturia -- heart failure, diabetes mellitus and diabetes insipidus, benign prostatic hyperplasia, nocturnal polyuria and reduced capacity -- have been ruled out.

Medications such as lithium, diuretics, selective serotonin reuptake inhibitors (SSRIs) and calcium channel blockers are examined to see if these could be causing a problem. When everything else has been evaluated, and the patient continues with nocturia, obstructive sleep apnea (OSA) is often then considered.

Coming from a sleep background, I wonder why OSA isn't the first thing entertained when the patient complains of nocturia. Patients with untreated OSA often have complaints of multiple visits to the bathroom throughout the night. What often happens is the patient is referred for benign prostatic hyperplasia if it's a man, and reduced capacity or incontinence if it's a woman.

Considering the role of the hormones vasopressin (AVP) and atrial natriuretic peptide (ANP) during sleep, it is wise to consider the possibility of OSA, especially if there are symptoms of unrefreshing sleep and daytime sleepiness.

In a 2003 study, Umlauf et al found that negative intrathoracic pressures created during an apneic event cause a “false sign of fluid overload.” This in turn causes a physiological response that causes the body to excrete ANP. ANP is a diuretic, so the patient is up to the bathroom multiple times a night.

Significant elevations of ANP were found in the patients they tested who also had OSA. They were even able to correlate the severity of a patient's sleep apnea depending on the frequency of their bathroom visits.  

In clinical practice, I have seen time and time again that treating a patient's sleep apnea also treats their nocturia. Waking frequently during the night disturbs a patient's sleep and makes for an exhausting day. Having this occur night after night is not healthy.

The next time a patient complains of nocturia and they have symptoms of sleep apnea, consider doing a sleep study before sending them to an urologist for a potential battery of unnecessary tests and medication. Your patient, and the urologist, will be happy that you did.

Sharon M. O'Brien, MPAS, PA-C, is a practicing clinician with an interest is helping patients understand the importance of sleep hygiene and the impact of sleep on health.

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