What Is Unilateral Renal Agenesis

Unilateral renal agenesis, often referred to as URA, is a rare congenital condition (the condition is present from birth) that occurs in approximately 1 in 1,000 live births.¹ It is characterized by the presence of only one kidney in the body of an infant, in contrast to the usual pair we are supposed to have.

While the idea of having just one kidney may not initially raise concerns because children with URA typically appear healthy and don't experience symptoms, there are potential health concerns that could develop in adulthood. Let's explore its causes, symptoms, diagnosis, and potential effects on an individual's health and investigate the available treatments for URA.

Understanding unilateral renal agenesis and its causes

To properly grasp the concept of URA, it's essential to have a basic understanding of how our kidneys develop. During prenatal development, our bodies start forming various organs, including a pair of kidneys — one on each side.

These kidney structures may resemble perfectly shaped beans, but their function is far from ordinary. They play a crucial role in our body by filtering our blood, maintaining fluid balance, regulating electrolytes, and controlling blood pressure.²

When it comes to URA, it means that one of those two kidneys didn't quite get the signal to grow or get the chance to fully develop in the womb, resulting in a single kidney at birth. In some cases, URA can follow an autosomal dominant inheritance pattern.³

This means that if one parent carries the altered gene responsible for URA, there is a 50% chance of passing it on to their children. URA can also be associated with certain genetic syndromes, such as VACTERL association, a complex condition that affects various organs in the body, including the kidneys.⁴ 

These two scenarios represent the possible causes of URA, but causes are still a subject of ongoing research. Some other potential factors include:

• Genetics: URA may be linked to genetic mutations or variations influencing kidney development. These genetic changes can disrupt the normal formation of fetal kidneys, particularly during the first trimester of pregnancy
• Environmental factors: Exposure to factors like maternal smoking, alcohol consumption, and certain medications may cause URA
• Idiopathic: In some instances, URA occurs without a clearly identifiable cause and is categorized as idiopathic
• Less common causes: Other causes may include gestational diabetes and multiple pregnancies, such as having twins, triplets, or more

The unilateral renal agenesis experience

In many cases, URA is asymptomatic, meaning individuals with this condition do not experience any noticeable symptoms or health issues related to their kidney absence, both in childhood and adulthood. This is because the single-functioning kidney can usually perform its necessary functions without causing problems.

However, it's important to note that while the condition may remain symptom-free in most cases, there is potential for certain health issues to develop over time. This risk becomes more apparent when we consider that the single kidney is tasked with double the workload and may be at a higher risk for diseases like kidney infections and kidney stones.

This insight is supported by a systematic review of over 40 studies, shedding light on URA's health implications.⁵ The study found that a small percentage of URA patients experienced kidney damage and reduced kidney function, while a larger portion suffered from urinary tract problems, such as vesicoureteral reflux.^6,7 Additionally, patients exhibited health issues beyond the kidneys, including high blood pressure.

These findings suggest that, despite the relative rarity of the condition, URA can have more significant health implications than previously believed. Therefore, it's crucial to identify symptoms early on if they present themselves.

Symptoms and possible complications of unilateral renal agenesis

While URA can be present with no symptoms or complications, it's essential to understand that the possibility of them still exists. Let's look at the possible symptoms and health issues that can come with the condition:

• Kidney-related symptoms: URA can occasionally lead to kidney problems, such as recurrent kidney infections or kidney stones, which are noticed through pain and discomfort in the back or side
• High blood pressure (Hypertension): The single present kidney in URA patients has to work harder to carry out functions of the kidney, which increases stress and strain, potentially leading to elevated blood pressure
• Urinary tract issues: In some cases, individuals with URA may experience urinary tract problems, including vesicoureteral reflux (a condition where urine flows backwards from the bladder into the ureters – two thick tubes that move urine from the kidney to the bladder
• Potential complications: Although URA itself may be asymptomatic, it's important to be aware of the potential for health issues related to having a single kidney, such as an increased risk of kidney disease

Again, not everyone with URA will experience these symptoms or complications, and some individuals may remain symptom-free throughout their lives. Regular medical check-ups and monitoring are crucial for individuals with URA. This will help detect and manage any of the symptoms or potential health issues that may arise.

Diagnosing unilateral renal agenesis

Diagnosing URA typically occurs through prenatal ultrasounds early in life. In other cases, when individuals experience symptoms associated with kidney problems, further investigations may reveal URA.

Methods of diagnosis include:

• Ultrasound: Prenatal ultrasounds can reveal the absence of one kidney
• CT Scan or MRI: Imaging tests may be ordered if URA is suspected due to symptoms or findings during a physical examination
• Voiding Cystourethrogram (VCUG): This test is performed to assess the structure and function of the urinary tract

Once diagnosed, medical professionals will assess the individual's overall health and guide on maintaining kidney health.

Living with unilateral renal agenesis

Living with a single kidney due to Unilateral Renal Agenesis (URA) isn't viewed as an issue for many because it doesn't significantly affect daily life. However, some considerations and precautions are important:

Monitoring kidney health

Regular visits to the doctor, paired with kidney function monitoring, are essential for individuals with URA. This includes blood pressure checks, urine tests, and occasional kidney function tests. Detecting and managing any kidney-related issues as soon as possible is essential.

Staying hydrated

Adequate hydration is essential to help prevent kidney stones and maintain overall kidney health. Drinking ample water regularly can help flush out waste products and reduce the risk of kidney-related complications.

Healthy lifestyle

Adopting a healthy lifestyle can help protect the single kidney. This includes maintaining a balanced, kidney-friendly diet, engaging in regular physical activity, avoiding smoking, and moderating alcohol intake.⁸

Medical precautions

Individuals with URA should inform healthcare providers about their condition before undergoing any medical procedures, as it may affect the choice of medications, anaesthesia, or certain diagnostic tests.

Unilateral renal agenesis treatment and interventions

In most cases, individuals with URA do not require specific treatment for their condition. The single kidney typically functions adequately, and the absence of symptoms or complications means no intervention is needed.

However, there are instances where treatment or intervention may be necessary. These include:

• Complications: If complications arise due to the single-functioning kidney, such as recurrent kidney infections, high blood pressure, or kidney stones, medical treatment or management may be required
• Surgical procedures: In rare cases, corrective surgical procedures may be considered to address specific issues associated with URA

Summary

URA is a condition where individuals are born with only one kidney. While many individuals with URA do not experience symptoms or health problems related to their condition, regular monitoring of kidney function and lifestyle changes is essential. Treatment is typically only necessary in cases of complications or specific medical issues. Awareness and proactive care can help individuals with URA lead healthy and fulfilling lives.