Introduction
Nocturia is a condition that causes you to wake up in the night regularly with a strong urgency to urinate. Patients who suffer from chronic kidney disease (CKD) often suffer from the challenges presented by nocturia. CKD is a long-term condition where your kidneys slowly get damaged, losing the ability to filter your blood. Patients with CKD usually experience nocturia, due to the decline in kidney function. According to Kidney Research UK, CKD affects more than 10% of the UK population. Besides nocturia, CKD can also impact other areas of a person’s health including, cardiovascular health, blood pressure, cognitive function, and more. Despite a high prevalence of CKD, early detection and awareness is low. This article will bring awareness to the impact of nocturia in patients with CKD and focus on the importance of understanding nocturia in CKD patients.
Understanding nocturia
Nocturia is a condition leading to the need to pass urine during the main sleeping period. Contrary to the normal urinary pattern of minimal to no need to urinate at night. It usually increases with age and is common amongst elderly people, affecting more than 50% of adults over 50. However, it can affect up to 1 in 3 people over 30 years old.
Symptoms of nocturia include:
- Waking up twice or more to urinate at night
- Increase in urine production, if polyuria is present. Polyuria is urinating too much measured in millilitres (total volume of pee) but not necessarily urinating too many times
- Fatigue and sleepiness during the day due to urinating so frequently it can interrupt your sleep cycle
Nocturia can be further categorised into 3 categories: nocturnal polyuria, global polyuria, and bladder storage disorders. Global polyuria is described as a continuously raised urine output defined as >40 mL/kg/24 hours. Nocturnal polyuria (NP) is described as an increased urine production at night with a >20% increase in 24-hour voided urine volume in young adults and >33% in older adults. Bladder storage issues are due to changes to the reservoir capacity of the bladder that increase voiding frequency.
Overview of chronic kidney disease:
Chronic kidney disease (CKD) is the presence of kidney damage or an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m², lasting for 3 months or more. There are 5 stages of CKD, these 5 stages indicate the functionality level of the kidneys.
CKD Stages and its indication:
- Stage 1 - normal eGFR of 90 or greater with mild damage to your kidneys, but kidneys are performing normally
- Stage 2 - eGFR has dropped to between 60 and 89 with mild damage to the kidneys and kidneys still performing normally
- Stage 3 - eGFR between 30 and 59 and mild to moderate damage to your kidneys with kidneys not performing so well with a reduced ability to filter waste and extra fluid out of the blood. This is split into two substages:
- Stage 3a indicates an eGFR of 45 and 59
- Stage 3b indicates an eGFR of 30 and 44
- Stage 4 - eGFR between 15 and 29 and moderate to severe damage to your kidneys, the kidneys are close to not working at all. The build-up of waste products in the blood will lead to health problems, like high blood pressure, bone disease, and heart disease. This is also the last stage before kidney failure
- Stage 5:eGFR less than 15 and severe damage to your kidneys with the kidneys very close to not working or have stopped working. At this stage, due to the build of waste products in your blood, you will be very ill and other health conditions will likely be present
Loss of kidney function can lead to a buildup of fluid, body waste or electrolyte problems. Depending on the severity, symptoms can look like this:
- Nausea/vomiting
- Fatigue and weakness
- Urinating more or less
- Sleep problems
- Swelling of feet and ankles
CKD is a consequence of a condition or disease that damages kidney function, causing kidney damage to worsen over a long period. Diseases and conditions that cause CKD include:
- Type 1 or type 2 diabetes
- Hypertension (High blood pressure)
- Pyelonephritis (a recurring kidney infection)
- Glomerulonephritis (an inflammation of the kidney's filtering units, also known as the glomeruli)
- Prolonged obstruction of the urinary tract, from conditions like enlarged prostate, kidney stones and some cancers
Potential complications of CKD:
- Fluid retention, leading to swelling in your arms and legs, high blood pressure, or fluid in your lungs (pulmonary oedema)
- A sudden rise in potassium levels in your blood (hyperkalemia), impairs your heart's function and can be life-threatening
- Heart disease
- Irreversible damage to your kidneys also known as end-stage kidney disease, eventually needing either dialysis or a kidney transplant for survival
Mechanisms linking CKD and nocturia
Nocturia can happen early on during CKD. As the kidney function declines, different physiological changes and conditions can contribute to nighttime urination, such as:
- Hormonal changes: As you age there is less antidiuretic hormone (ADH) produced. ADH is a chemical that your body makes to help regulate water balance, this would be disrupted in CKD. As your kidney function declines, your kidneys may not respond efficiently enough to ADH. So, when lower levels of ADH are secreted, there will be decreased water reabsorption causing more urine to be produced at night
- Heart problems: If you have a heart condition, your heart and circulation become less efficient with symptoms of swelling around your ankles. When you lie down or your feet are raised up, fluid retention occurs and this fluid is absorbed into your blood. This leads to increased urine production. This is also known as ‘nocturnal diuresis’
- Diabetes: When poorly controlled, diabetes can lead to diabetic nephropathy, which can result in an increase in urine production, because of high blood sugar levels. High blood sugar levels increase your thirst, causing you to drink more than normal, leading to an increase in urination frequency and also irritating the bladder causing nocturia
Furthermore, a study on the pathophysiology of nocturnal polyuria associated with renal dysfunction was done by the Department of Urology, Osaka University Graduate School of Medicine. The study showed that a decrease in renal function causes a decrease in nighttime urine osmolality and an increase in the nighttime salt, K, and UN excretion rates. Moreover, a correlation between an increase in the nighttime salt excretion rate and an increase in the nighttime urine volume rate. These results suggest a decreased kidney function similar to CKD patients can lead to nocturia.
Consequences of nocturia in CKD patients:
Nocturia can have significant consequences on CKD patients, impacting their quality of life, especially for the elderly. For example, they could experience :
- Disruptive sleeping habits: The increase in nighttime urination frequency can lead to interrupted sleep. Decreased sleep can cause daytime fatigue, poor concentration, memory impairment, and mood alterations and affect overall work performance
- Increased risks of falls and injuries: Fall and hip fracture risk is increased in elderly patients as they may already have compromised mobility and balance
- Electrolyte imbalance: Nocturia may worsen kidney function, leading to possible complications, such as electrolyte imbalance
Management and treatment options:
Proper management and effective treatment of nocturia are vital for enhancing the quality of life in CKD patients. This could include:
- Lifestyle management:
- Restricting fluids in the evening (especially caffeinated beverages)
- Elevating your legs while you’re sitting at home helps with fluid distribution
- Pelvic floor exercises to strengthen your pelvic floor muscles
- Wearing compression stockings can also help with fluid distribution
- Medications:
- Anticholinergics: These medications reduce symptoms of overactive bladder. Up to 40% of people find success with anticholinergics. Examples of this type of medication include mirabegron, darifenacin, oxybutynin, and tolterodine
- Diuretics: Medications like bumetanide and furosemide assist in regulating how much pee you produce
- Patient education: Educating patients about nocturia and CKD is vital because it can encourage patient compliance with their management plan
Summary
Nocturia is a challenging condition that is present in patients with chronic kidney disease that can impact their quality of life and sleep. Physiological changes can include decreased kidney function, which can lead to an increased frequency of nighttime urination. Alongside this, complications and consequences can occur like disruptive sleeping habits, increased risk of falls and injuries, and electrolyte imbalance. Implementing management strategies with lifestyle management and pharmacological management with medications can help improve the quality of life for CKD patients. Furthermore, addressing underlying health conditions can optimize health outcomes. Most importantly, patient education on the complexities of nocturia in CKD patients is crucial for enhancing the quality of life and patient comfortability.
References
- Kidney Research UK. Kidney disease: A UK public health emergency The health economics of kidney disease to 2033 [Internet]. 2023 Jun [cited 2024 Sep 5]. Available from: https://www.kidneyresearchuk.org/wp-content/uploads/2023/06/Economics-of-Kidney-Disease-full-report_accessible.pdf
- Cleveland Clinic. Nocturia [Internet]. Cleveland Clinic. 2020 [cited 2024 Sep 5]. Available from: https://my.clevelandclinic.org/health/diseases/14510-nocturia
- Prince D, Pedler K, Rashid P. Nocturia A guide to assessment and management [Internet]. 2012 [cited 2024 Sep 5]. Available from: https://www.racgp.org.au/getattachment/b43c05ba-e29e-47c3-b816-ec47ceeafe97/Nocturia-a-guide-to-assessment-and-management.aspx
- American Kidney Fund. Stages of kidney disease [Internet]. www.kidneyfund.org. 2022 [cited 2024 Sep 5]. Available from: https://www.kidneyfund.org/all-about-kidneys/stages-kidney-disease
- Mayo Clinic. Chronic kidney disease [Internet]. Mayo Clinic. 2023 [cited 2024 Sep 5]. Available from: https://www.mayoclinic.org/diseases-conditions/chronic-kidney-disease/symptoms-causes/syc-20354521
- Takezawa K, Kuribayashi S, Okada K, Sekii Y, Inagaki Y, Fukuhara S, et al. Decreased renal function increases the nighttime urine volume rate by carryover of salt excretion to the nighttime. Scientific Reports. 2021 May 19;11(1).