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19.5: Disorders of the Urinary System - Biology


Awareness Ribbon

Awareness ribbons are symbols meant to show support or raise consciousness for a cause. Different colors are associated with different issues, often relating to health problems. The first ribbon to gain familiarity for a health issue was the red ribbon for HIV/AIDS, created in 1991. The pink ribbon for breast cancer awareness is probably the best known today. Do you know what a green ribbon like the one pictured in Figure (PageIndex{1}) represents? Among several other health problems, a green ribbon is meant to show support or raise awareness for kidney disorders.

The kidneys play such vital roles in eliminating wastes and toxins and maintaining body-wide homeostasis that disorders of the kidneys may be life-threatening. The gradual loss of normal kidney function commonly occurs with a number of disorders, including diabetes mellitus and high blood pressure. Other disorders of the kidneys are caused by faulty genes that are inherited. Loss of kidney function may eventually progress to kidney failure.

Diabetic Nephropathy

Diabetic nephropathy is a progressive kidney disease caused by damage to the capillaries in the glomeruli of the kidneys due to long-standing diabetes mellitus (see Figure (PageIndex{2})). It is not fully understood how diabetes leads to damage of glomerular capillaries, but it is thought that high levels of glucose in the blood are involved. In people with diabetes, nephropathy is more likely if their blood glucose is poorly controlled. Having high blood pressure, a history of cigarette smoking and a family history of kidney problems are additional risk factors. Diabetic nephropathy often has no symptoms at first. In fact, it may take up to a decade after kidney damage begins for symptoms to appear. When they do appear, they typically include severe tiredness, headaches, nausea, frequent urination, and itchy skin.

Proteins are large molecules that usually are not filtered out of blood in the glomeruli. When the glomerular capillaries are damaged, it allows proteins such as albumin to leak into the filtrate from the blood. As a result, albumin ends up being excreted in the urine. Finding a high level of albumin in the urine is one indicator of diabetic nephropathy and helps to diagnose the disorder. Drugs may be prescribed to reduce protein levels in the urine. Controlling high blood sugar levels and hypertension (high blood pressure) is also important to help slow kidney damage, as is a reduction of sodium intake.

Polycystic Kidney Disease

Polycystic kidney disease (PKD) is a genetic disorder in which multiple abnormal cysts develop and grow in the kidneys. Figure (PageIndex{3}) shows a pair of kidneys that are riddled with cysts from PKD. In people who inherit PKD, the cysts may start to form at any point in life from infancy through adulthood. Typically, both kidneys are affected. Symptoms of the disorder may include high blood pressure, headaches, abdominal pain, blood in the urine, and excessive urination.

There are two types of PKD. The more common type is caused by an autosomal dominant allele, and the less common type is caused by an autosomal recessive allele. Both types collectively make PKD one of the most common hereditary diseases in the United States, affecting more than half a million people. There is little or no difference in the rate of occurrence of PKD between genders or ethnic groups. There is no known cure for this disease other than a kidney transplant.

Kidney Failure

Both diabetic nephropathy and PKD may lead to kidney (or renal) failure (classified as end-stage kidney disease), in which the kidneys are no longer able to adequately filter metabolic wastes from the blood. Long-term, uncontrolled high blood pressure is another common cause of kidney failure. Symptoms of kidney failure may include nausea, more or less frequent urination, blood in the urine, muscle cramps, anemia, swelling of the extremities, and shortness of breath due to the accumulation of fluid in the lungs. If kidney function drops below the level needed to sustain life, then the only treatment option is kidney transplantation or some means of artificial filtration of the blood, such as by hemodialysis.

Hemodialysis is a medical procedure in which blood is filtered externally through a machine. You can see how it works in the simplified diagram in Figure (PageIndex{4}). During dialysis, waste products such as urea as well as excess water are removed from the patient’s blood before the blood is returned to the patient. Hemodialysis is typically done on an outpatient basis in a hospital or special dialysis clinic. Less frequently, it is done in the patient’s home. Depending on the patient’s size, among other factors, the blood is filtered for 3 to 4 hours about 3 times a week. Because the treatment is needed so frequently, hemodialysis is one of the most common procedures performed in U.S. hospitals.

Kidney Stones

A kidney stone, also known as a renal calculus, is a solid crystal that forms in a kidney from minerals in urine (see Figure (PageIndex{5})). The majority of kidney stones consist of crystals of calcium salts. Kidney stones typically leave the body in the urine stream. A small stone may pass through the ureters and other urinary tract organs without causing symptoms and go undetected. A larger stone may cause pain when it passes through the urinary tract. If a kidney stone grows large enough, it may block the ureter. Blockage of a ureter may cause a decrease in kidney function and damage to the kidney.

A kidney stone that causes pain is generally treated with pain medication until it passes through the urinary tract. A stone that causes a blockage may be treated with lithotripsy. This is a medical procedure in which high-intensity ultrasound pulses are applied externally to cause fragmentation of the stone into pieces small enough to pass easily through the urinary tract. Although lithotripsy is noninvasive, it can cause damage to the kidneys. An alternative treatment for a stone that blocks urine flow is to insert a stent into the ureter to expand it and allow both urine and the stone to pass. In some cases, surgery may be required to physically remove a large stone from the ureter.

A combination of lifestyle and genetic factors seem to predispose certain people to develop kidney stones. Risk factors include high consumption of cola soft drinks, eating a diet high in animal protein, being overweight, and not drinking enough fluids. Preventive measures are obvious. They include limiting cola consumption, eating less animal protein, losing weight, and increasing fluid intake.

Other Urinary System Disorders

Although disorders of the kidneys are generally the most serious urinary system disorders, problems that affect other organs of the urinary tract are generally more common. They include bladder infections and urinary incontinence.

Bladder Infection

A bladder infection, also called cystitis, is a very common type of urinary tract infection in which the urinary bladder becomes infected by bacteria (typically Escherichia coli), rarely by fungi. Symptoms of bladder infections may include pain with urination, frequent urination, and feeling the need to urinate despite having an empty bladder. In some cases, there may be blood in the urine. A much less common type of urinary tract infection is pyelonephritis, in which the kidney becomes infected. If a kidney infection occurs, it is generally because of an untreated bladder infection. Bladder infections are treated mainly with antibiotics.

Risk factors for urinary bladder infections include sexual intercourse (especially when spermicide or a diaphragm, as shown in Figure (PageIndex{6}), is used for contraception), diabetes, obesity, and most importantly, female sex. Bladder infections are four times more common in women than in men. In fact, in women, they are the most common type of bacterial infection, and as many as 1 in 10 women has a bladder infection in any given year. Female anatomy explains the sex difference in the incidence of bladder infections. The urethra is much shorter and closer to the anus in females than in males, so contamination of the urethra and then the bladder with GI tract bacteria is more likely in females than in males. Once the bacteria reach the bladder, they can attach to the bladder wall and form a biofilm that resists the body’s immune response.

Urinary Incontinence

Urinary incontinence is a chronic problem of uncontrolled leakage of urine. It is very common, especially at older ages and especially in women. Sometimes urinary incontinence is a sign of another health problem, such as diabetes or obesity. Regardless of the underlying cause, the symptoms of urinary incontinence alone may have a large impact on the quality of life, frequently causing inconvenience, embarrassment, and distress.

In a person with male anatomy, urinary incontinence is most commonly caused by an enlarged prostate gland or treatment for prostate cancer. In genetically female individuals, there are two common types of urinary incontinence with different causes: stress incontinence and urge incontinence.

  • Stress urinary incontinence is caused by loss of support of the urethra, usually due to stretching of pelvic floor muscles during childbirth. It is characterized by leakage of small amounts of urine with activities that increase abdominal pressure, such as coughing, sneezing, or lifting. Treatment of stress urinary incontinence may include Kegel exercises to strengthen the pelvic muscles (see Explore More below). More serious cases may call for surgery to improve support for the bladder.
  • Urge urinary incontinence (commonly called “overactive bladder”) is caused by uncontrolled contractions of the detrusor muscle in the wall of the bladder. This causes the bladder to empty unexpectedly. Urge incontinence is characterized by leakage of large amounts of urine in association with an insufficient warning to get to the bathroom in time. Treatment of urge incontinence may include taking medication to relax the detrusor muscle.

Feature: My Human Body

You probably have had to “donate” a urine specimen for analysis in conjunction with a medical visit. A thorough medical exam often includes clinical tests for urine. Understanding what your urine may reveal about your health may help you appreciate the need for such tests.

The most common urine test is called a urinalysis. In a routine urinalysis, a urine sample may be analyzed by sight and smell and with simple urine test strips. If a particular disorder is suspected, urinalysis may be more extensive. For example, the urine may be analyzed with specific tests or viewed under a microscope to identify abnormal substances in the urine. If a bacterial infection is suspected, a sample of urine may be cultured in the lab to see if it grows bacteria and which type of bacteria grow. Knowing the type of bacteria is important for deciding which class of antibiotics is likely to be most effective in treating the infection.

The color and clarity of urine may be obvious first indicators of disorders or other abnormalities. Normal urine is yellow to amber in color and looks clear. If urine is nearly colorless, it could be a sign of excessive fluid intake, or it might be a sign of diabetes. Very dark urine may indicate dehydration, but it could also be caused by taking certain medications or ingesting some other substances. If the urine has a reddish tinge, it is often a sign of blood in the urine, which could be due to a urinary tract infection, kidney stone, or even cancer. If the urine appears cloudy instead of clear, it could be due to white blood cells in the urine, which may be another sign of a urinary tract infection.

Normal urine may have virtually no odor if it is very dilute. It will have a stronger odor if it is concentrated. Brief changes in the normal odor of urine often occur due to the ingestion of certain foods or medications. For example, after eating asparagus, urine may have a peculiar and distinctive odor for several hours. More significant is urine that has a sweet smell, because this may indicate sugar in the urine, which is a sign of diabetes.

Urine test strips, much like the familiar litmus test strips used to detect acids and bases in a chemistry lab, are used to identify abnormal levels of certain components in the urine. For example, urine test strips can detect and quantify the presence of nitrites in urine, which is usually a sign of infection with certain types of bacteria. Urine test strips can also be used to identify proteins such as albumin in urine, which may be a sign of a kidney infection or of kidney failure. Levels of sodium in urine can also be measured with test strips, and higher-than-normal levels may be another indication of kidney failure. In addition, test strips can identify and quantify the presence of white blood cells and blood in a urine specimen, both of which are likely to be a sign of a urinary tract infection or some other urinary system disorder.

Besides the use of urine test strips, other simple urine tests that are often performed include Benedict’s test, which is a test for the presence and quantity of glucose in urine. If the level is high, it is likely to indicate diabetes. The test is so simple that it may even be done in the home by the patient to monitor how well sugar levels are being controlled. Testing for some other substances in urine requires the patient to collect urine over a 24-hour period. This is the case, for example, when testing for the adrenal hormone cortisol in urine. When urine cortisol levels are higher than normal it may indicate Cushing’s syndrome, and when the levels are lower than normal it may indicate Addison’s disease.

Review

  1. What is diabetic nephropathy and what causes it?
  2. Describe polycystic kidney disease (PKD).
  3. Define kidney failure.
  4. What are potential treatments for kidney failure when kidney function drops below the level needed to sustain life?
  5. Describe hemodialysis.
  6. What are kidney stones?
  7. How may a large kidney stone be removed from the body?
  8. How are bladder infections usually treated?
  9. Why are bladder infections much more common in females than in males?
  10. Define urinary incontinence.
  11. Compare and contrast stress incontinence and urge incontinence.
  12. Why is the presence of a protein such as albumin in the urine a cause for concern?
  13. Patients undergoing hemodialysis usually have to do this procedure a few times a week. Why does it have to be done so frequently?
  14. Which of the following is considered a genetic disorder?

    A. Polycystic kidney disease

    B. Diabetic nephropathy

    C. Kidney failure

    D. Urinary incontinence

  15. What is the most common cause of a kidney infection?

Explore More

Kegel exercises can strengthen the muscles of the pelvic floor and help many cases of urinary incontinence. You can learn more by watching this video:

Urinary tract infections can be very painful. Learn more about their symptoms, causes, complications and treatments here:


Medical Careers Involved With the Urinary System

Of the many medical specialties available for physicians, several deal with the urinary system. These urinary system specialists may provide medical management, surgical management or gynecological management. The primary specialties that deal with the urinary tract system are urology, nephrology, gynecology and transplant surgery. Several subspecialties, such as female pelvic medicine and reconstructive surgery, also exist. All require extensive training and a great deal of responsibility. Surgical residencies can last up to seven years, according to the American College of Surgeons.


Urinary Bladder

The urinary bladder is a hollow, muscular, and stretchy organ that rests on the pelvic floor. It collects and stores urine from the kidney s before the urine is eliminated through urination . As shown in Figure 16.5.4, urine enters the urinary bladder from the ureters through two ureteral openings on either side of the back wall of the bladder. Urine leaves the bladder through a sphincter called the internal urethral sphincter. When the sphincter relaxes and opens, it allows urine to flow out of the bladder and into the urethra.

Figure 16.5.4 This diagram of the urinary bladder shows (a) a cross-sectional drawing of the entire bladder and (b) a microscopic cross-section of the tissues in the wall of the bladder.

Like the ureters, the bladder is lined with transitional epithelium, which can flatten out and stretch as needed as the bladder fills with urine. The next layer (lamina propria) is a layer of loose connective tissue, nerves, and blood and lymphatic vessels. This is followed by a submucosa layer, which connects the lining of the bladder with the detrusor muscle in the walls of the bladder. The outer covering of the bladder is peritoneum, which is a smooth layer of epithelial cells that lines the abdominal cavity and covers most abdominal organs.

The detrusor muscle in the wall of the bladder is made of smooth muscle fibres controlled by both the autonomic and somatic nervous systems. As the bladder fills, the detrusor muscle automatically relaxes to allow it to hold more urine. When the bladder is about half full, the stretching of the walls triggers the sensation of needing to urinate. When the individual is ready to void, conscious nervous signals cause the detrusor muscle to contract, and the internal urethral sphincter to relax and open. As a result, urine is forcefully expelled out of the bladder and into the urethra.


Ayurvedic Treatment for Urinary Problem

Diseases affecting the urinary tract and kidneys are broadly termed as Mutravahasrota Roga in Ayurveda.
Generally, the diseases affecting the bladder and urethra are known as Mutraghata.
According to the Madhav Nidaan, Mutraghata is of 13 kinds:
1. Vatakundalika (spasmodic stricture of the bladder)
2. Vatasthila (Enlargement of prostate)
3. Vatavasti (Obstruction of the bladder outlet retention of urine)
4. Mutratita (Decrease in force of urinary stream incontinence of urine)
5. Mutrajathara (Distended bladder with urine and gas)
6. Mutrasanga (Stricture of urethra)
7. Mutrakshaya (Anuria)
8. Mutragranthi (Malignant neoplasm/tumor of the bladder)
9. Mutrashukra (Semen in urine)
10. Usnavata (Cystitis, gonorrhea)
11. Vastikundalam (Atonic condition of the bladder)
12. Vidavighat (Retrovesical fistula)
13. Mutrasada (Crystalluria scanty urination)

Metabolic diseases that are characterized by excessive urination (polyuria) are usually known as Prameha.
As is mentioned before and as the names suggest, disorders of the urinary tract are caused by the Vata dosha. The diseases can be treated with the help of diuretics (mutravirechana). Diuretics stimulate the flow of urine and balance the downward flow of Vata dosha.


Anatomy and physiology of the lower urinary tract

Functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. Neural control of micturition is organized as a hierarchic system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brainstem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brainstem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily during the early postnatal period, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults cause re-emergence of involuntary micturition, leading to urinary incontinence. The mechanisms underlying these pathologic changes are discussed.

Keywords: afferent nerves parasympathetic periaqueductal gray pontine micturition center smooth muscle spinal cord sympathetic urethra urinary bladder urothelium.


Analysis of urinary exosomes applications for rare kidney disorders

Introduction: Exosomes are nanovesicles that play important functions in a variety of physiological and pathological conditions. They are powerful cell-to-cell communication tool thanks to the protein, mRNA, miRNA, and lipid cargoes they carry. They are also emerging as valuable diagnostic and prognostic biomarker sources. Urinary exosomes carry information from all the cells of the urinary tract, downstream of the podocyte. Rare kidney diseases are a subset of an inherited diseases whose genetic diagnosis can be unclear, and presentation can vary due to genetic, epigenetic, and environmental factors. Areas covered: In this review, we focus on a group of rare and often neglected kidney diseases, for which we have sufficient available literature data on urinary exosomes. The analysis of their content can help to comprehend pathological mechanisms and to identify biomarkers for diagnosis, prognosis, and therapeutic targets. Expert opinion: The foreseeable large-scale application of system biology approach to the profiling of exosomal proteins as a source of renal disease biomarkers will be also useful to stratify patients with rare kidney diseases whose penetrance, phenotypic presentation, and age of onset vary sensibly. This can ameliorate the clinical management.

Keywords: Exosomes biomarker proteomics rare kidney diseases.


19.5: Disorders of the Urinary System - Biology

Renal failure uremia is a syndrome of renal failure characterized by elevated levels of urea and creatinine in the blood.

Learning Objectives

Distinguish between acute kidney injury and chronic kidney disease

Key Takeaways

Key Points

  • The type of renal failure is determined by the trend in the serum creatinine.
  • In renal failure, there may be problems with increased fluid in the body (leading to swelling), increased acid levels, raised levels of potassium, decreased levels of calcium, increased levels of phosphate, and in later stages, anemia.
  • The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.

Key Terms

  • renal calculus: A solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine a kidney stone.
  • creatinine: A heterocyclic amine 2-amino-1-methyl-5H-imidazol-4-one formed by the metabolism of creatine.
  • renal failure uremia: Uremia is a term used to loosely describe the illness accompanying kidney failure (also called renal failure), in particular the nitrogenous waste products associated with the failure of this organ.

Examples

Before dialysis or kidney transplants were widely available treatments, patients with kidney failure had progressive uremic poisoning. These days, most patients have some early symptoms of uremia as their kidney function declines, but prompt dialysis treatments or transplantation avoids most symptoms.

Renal failure (also kidney failure or renal insufficiency) is a medical condition in which the kidneys fail to adequately filter waste products from the blood. The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.

Diagnosis

Renal failure is mainly determined by a decrease in the glomerular filtration rate, which is the rate at which blood is filtered in the glomeruli of the kidney. This is detected by a decrease in or absence of urine production or determination of waste products (creatinine or urea ) in the blood. Depending on the cause, hematuria (blood loss in the urine) and proteinuria (protein loss in the urine) may be noted.

In renal failure, there may be problems with increased fluid in the body (leading to swelling), increased acid levels, raised levels of potassium, decreased levels of calcium, increased levels of phosphate, and in later stages, anemia. Bone health may also be affected. Long-term kidney problems are associated with an increased risk of cardiovascular disease.

Categories of Renal Failure

Renal failure can be divided into two categories: acute kidney injury or chronic kidney disease. The type of renal failure is determined by the trend in the serum creatinine. Other factors that may help differentiate acute kidney injury from chronic kidney disease include anemia and the kidney size on ultrasound. Chronic kidney disease generally leads to anemia and small kidney size.

Kidney Transplantation: Kidney transplantation requires a person to be at the end stage of renal failure.

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine production, quantified as less than 400 mL per day in adults, less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants) and fluid and electrolyte imbalance. AKI can result from a variety of causes, generally classified as prerenal, intrinsic, and postrenal. An underlying cause must be identified and treated to arrest the progress, and dialysis may be necessary to bridge the time gap required for treating these fundamental causes.

Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms. CKD can be the long-term consequence of irreversible acute disease or part of a disease progression.

Acute kidney injuries can be present on top of chronic kidney disease, a condition called acute-on-chronic renal failure (AoCRF). The acute part of AoCRF may be reversible, and the goal of treatment, as with AKI, is to return the patient to baseline renal function, typically measured by serum creatinine. Like AKI, AoCRF can be difficult to distinguish from chronic kidney disease if the patient has not been monitored by a physician and no baseline (i.e., past) blood work is available for comparison.

Symptoms can vary from person to person. Someone in early stage kidney disease may not feel sick or notice symptoms as they occur. When kidneys fail to filter properly, waste accumulates in the blood and the body, a condition called azotemia. Very low levels of azotaemia may produce few, if any, symptoms. If the disease progresses, symptoms become noticeable (if the failure is of sufficient degree to cause symptoms). Renal failure accompanied by noticeable symptoms is termed uraemia.

Renal Failure Uremia

Renal failure uremia is a syndrome of renal failure that includes elevated blood urea and creatinine levels. Acute renal failure can be reversed if diagnosed early. Acute renal failure can be caused by severe hypotension or severe glomerular disease. Diagnostic tests include BUN and plasma creatinine level tests. It is considered to be chronic renal failure if the decline of renal function is to less than 25%.


Cause Cause

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

  • To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from MedlinePlus Genetics.

Urinary Bladder Function

The function of the urinary bladder is to collect and store urine from the kidneys until it can be excreted via urination. The typical human bladder can store an average of 300 mL to 500 mL of urine. As described above, the urinary bladder is highly elastic and is able to accommodate an increased volume of liquid due to the flattening of the rugae folds. Urination is not controlled by the bladder, but rather the pontine micturition center in the brain.


More than just anatomy—sex differences in the lower urinary tract

The biological differences between women and men go beyond basic anatomy. Researchers must consider sex differences down to the cellular level in order to discover crucial information about the varied development, function, and biology between women and men.

A new report written by the Society for Women's Health Research's Interdisciplinary Network on Urological Health in Women and published today in the Biology of Sex Differences journal highlights how improving our knowledge about sex differences in cell biology in the female and male lower urinary tract may help stimulate breakthroughs in the diagnosis and management of urinary dysfunction for both women and men.

For example, while anatomical differences between the sexes have long been thought to be the reason women experience significantly more urinary tract infections (UTIs) than men, more recent evidence supports the existence of other, non-anatomical contributors to women's increased vulnerability.

The location of the female external urethra and the shorter length of that urethra are typically cited as why women get UTIs up to 30 times more often than men do, with more than half of all women experiencing at least one UTI during their lifetime. However, recent research investigating the role of the reticuloendothelial system, which provides immunity against microbes, suggests that differential expression of immune cells in the bladder may amplify the rate of UTIs in women.

"In addition to our basic anatomy, women and men exhibit sex differences at the cellular level that influence both the form and function of the lower urinary tract," said senior author Margot S. Damaser, Ph.D., staff and professor at the Cleveland Clinic and senior research scientist at the Cleveland VA Medical Center. "These differences need to be taken into account when treating urinary dysfunction in order to provide optimal treatment for both women and men."

The authors note that the review paper should serve as an overview of the current knowledge regarding sex differences in the lower urinary tract, as well as a catalyst for investigators seeking to contribute to the field.

Further investigation of sex differences in lower urinary tract cell types is necessary to better develop our understanding of normal and abnormal function, and specifically, the paper states that more research is needed regarding: