Nocturia is common, but elderly patients infrequently volunteer this complaint, and even when they do, some clinicians may dismiss it as simply a part of aging. Nevertheless, nocturia causes significant distress and impairment of quality of life. It is associated with very serious consequences such as depression, social isolation, and a higher risk of death.
In this article, we review the concepts behind frequent nighttime voiding in older adults. We will start with two case scenarios to aid in understanding these concepts; near the end of the article, we will discuss the most appropriate management strategies for these two patients.
Case 1: An 82-year-old man with fatigue
An 82-year-old obese white man with a history of hypertension, diabetes, and benign prostatic hyperplasia comes in to see his primary care provider, complaining of fatigue. He wakes up tired and has difficulty completing his daytime tasks. He gets up every 1 to 2 hours at night to urinate and has slow urinary flow and a feeling of incomplete bladder emptying.
He says his wife has been increasingly bothered by his loud snoring. Recently, he had a car accident when he fell asleep while driving.
Case 2: An 85-year-old woman with incontinence
An 85-year-old white woman is in her family physician’s office with a primary complaint of waking up at least four times at night to urinate, and often ends up soaking her bed or adult diapers. She is bothered by urinary urgency and frequency during the day as well. She denies dysuria and hematuria.
She has a history of hypertension and urinary incontinence, and she has seven children. Her current medications are diltiazem (Cardizem), metoprolol (Toprol), and oxybutynin (Ditropan).
In these two cases, what would account for the nocturia? What would be the best way to help these patients?
THE NORM, NOT THE EXCEPTION
Although nocturia is defined as an awakening by the need to urinate even once in a night, many experts consider that it begins to be clinically significant only when the patient voids at least twice during the night.1
In older adults, nocturia is the norm rather than the exception. Studies done between 1990 and 2009 found that 68.9% to 93% of men age 70 and older get up at least once a night to void. The prevalence in women is somewhat lower, at 74.1% to 77.1%.2 Clinically significant nocturia is present in a majority of the elderly: more than 60% of both men and women.3
An Austrian study4 reported that elderly men got up to urinate a mean of 2.8 times per night, while women got up significantly more often—3.1 times. Women were also bothered more by this symptom, and their quality of life was significantly more decreased.
In another study,5 whites had a significantly higher nocturia ratio (ratio of nighttime urine volume to the 24-hour urine volume) than Asians. Asians, on the other hand, had a significantly higher nocturnal bladder capacity index than whites. (See below for definitions of the various indices of nocturia.) This information implies that nocturia may be a more prominent problem for elderly whites than for other racial groups.
In an epidemiologic study in Sweden,6 the death rate was as much as twice as high in both men and women who had three or more nocturnal voids, even after taking into account the influence of cardiac disease, diabetes mellitus, and stroke.
If nocturia is not addressed in the physician-patient encounter, patients may try to “self-manage” it by restricting their fluid intake or by limiting their social exposure,7 with limited success and with unwanted social isolation.
WHAT CAUSES NOCTURIA?
In almost all cases of nocturia in elderly people, the cause is multifactorial (Table 1).
Advancing age is primary among these factors. Age-related structural changes in the urinary system include decreased functional bladder capacity, a decreased maximum urinary flow rate,6 a decreased ability to postpone urination,8 and an age-related increase in postvoiding residual urine volume.9 The aging kidney is also less able to concentrate urine. Also implicated are histologic changes in the detrusor muscle10 that lead to diminished bladder compliance and, together with detrusor overactivity, result in increased urinary frequency.
Nocturnal polyuria or nocturnal urine overproduction is common in patients with nocturia.11
Although the pathophysiology of nocturnal polyuria is still unclear, some investigators believe that low levels of antidiuretic hormone (ADH) at night are involved, reflecting an alteration in the circadian rhythm seen in diurnal plasma arginine vasopressin levels.12 In patients with nocturnal polyuria, ADH levels drop to very low or undetectable levels at night, which increases nocturnal urine output. In some extreme cases, the low to absent levels of ADH increase nocturnal voiding to 85% of the total 24-hour urine volume.13
Other causes of nocturnal polyuria include mobilization of fluids in patients with edema,14 and autonomic dysfunction. Other biochemical changes that contribute to nocturia include a decrease in nighttime plasma melatonin levels, an increase in nighttime plasma catecholamine levels, an increase in nighttime plasma natriuretic peptide levels, an increase in blood pressure, and an increase in total urine volume.15
A decreased ability to store urine also leads to nocturia. This is caused by decreased nocturnal bladder capacity, more irritative symptoms, and comorbid conditions such as overactive bladder, pelvic floor laxity resulting in pelvic organ prolapse, and, in men, benign prostatic hyperplasia.
Neural inputs to the bladder can also be impaired, as in patients who have diabetes mellitus or spinal stenosis, leading to chronic urinary retention, detrusor dysfunction, nocturia, and incontinence.