Symptoms & Diagnosis of Kidney & Urinary Tract Disorders

Diagnosis
During a physical examination of a person whose symptoms may indicate a kidney disorder, a doctor may attempt to feel the kidneys. Normal kidneys cannot usually be felt in children or adults (though they may be felt in newborn infants). Enlarged kidneys or a kidney tumor may be detectable.
Often, a distended bladder can be detected. The doctor may perform a rectal examination in a man to determine whether the prostate is abnormal or enlarged, although the size of the prostate does not always correlate with the degree of urethral obstruction. The doctor may perform a pelvic examination in a woman to determine whether vaginitis or the genital organs are contributing to urinary tract symptoms. Additional procedures may need to be performed to diagnose a kidney or urinary tract disorder.

Urinalysis
Urinalysis is testing of the urine. A urine sample is usually collected using the clean-catch method or another sterile method. For example, a method to obtain an uncontaminated urine sample involves passing a catheter through the urethra into the bladder.
Urinalysis can be used to detect and measure the level of various substances in the urine, including protein, glucose (sugar), ketones, blood, and other substances. These tests use a thin strip of plastic (dipstick) impregnated with chemicals that react with substances in the urine and quickly change color. Sometimes, the test results are confirmed with more sophisticated and accurate laboratory analysis of the urine. The urine may be examined under a microscope to check for the presence of red and white blood cells, crystals, and casts (impressions of the kidney tubules created when urinary cells, protein, or both precipitate out in the tubules and are passed in the urine).
Protein in the urine (proteinuria) can usually be detected by dipstick. Protein may appear constantly or only intermittently in the urine, depending on the cause. Proteinuria is usually a sign of kidney disorders, but it may occur normally after strenuous exercise, such as marathon running. Glucose in the urine (glucosuria) can be accurately detected by dipstick. The most common cause of glucose in the urine is diabetes mellitus, but absence of glucose does not mean a person does not have diabetes or that the diabetes is well controlled.
Ketones in the urine (ketonuria) can often be detected by dipstick. Ketones are formed when the body breaks down fat. Ketones can appear in the urine from starvation, uncontrolled diabetes mellitus, and occasionally after drinking significant amounts of alcohol.
Blood in the urine (hematuria) is detectable by dipstick and confirmed by viewing the urine with a microscope and other tests. Sometimes the urine contains enough blood to be visible, making the urine appear red or brown. Nitrites in the urine (nitrituria) are also detectable by dipstick. High nitrite levels indicate a urinary tract infection.
Leukocyte esterase (an enzyme found in certain white blood cells) in the urine can be detected by dipstick. Leukocyte esterase is a sign of inflammation, which is most commonly caused by a urinary tract infection. The acidity of urine is measured by dipstick. Certain foods, chemical imbalances, and metabolic disorders may change the acidity of urine.
The concentration of urine (also called the osmolality or specific gravity) can vary widely depending on whether a person is dehydrated, how much fluid a person has drunk, and other factors. Urine concentration is also sometimes important in diagnosing abnormal kidney function. The kidneys lose their capacity to concentrate urine at an early stage of a disorder that leads to kidney failure. In one special test, a person drinks no water or other fluids for 12 to 14 hours. In another test, a person receives an injection of antidiuretic hormone (also called vasopressin) . Afterward, urine concentration is measured. Normally, either test should make the urine highly concentrated. However, in certain kidney disorders (such as nephrogenic diabetes insipidus), the urine cannot be concentrated even though other kidney functions are normal.
Sediment in urine can be examined under a microscope to provide information about a possible kidney or urinary tract disorder. Normally, urine contains a small number of cells and other debris shed from the inside of the urinary tract. A person who has a kidney or urinary tract disorder usually sheds more cells, which form a sediment if urine is centrifuged or allowed to settle.

Urine Culture
Urine cultures, in which bacteria from a urine sample are grown in a laboratory, are performed to diagnose a urinary tract infection. Cultures are not part of routine urinalysis. The sample of urine must be obtained by the clean-catch method or by briefly inserting a sterile catheter through the urethra into the bladder.

Kidney Function Tests
Doctors can assess kidney function by performing tests on blood and urine samples. Creatinine, a waste product, is increased in the blood when the kidney filtration rate is decreased by a large amount. Creatinine clearance-a more accurate test-can be approximated from a blood sample using a formula that relates the creatinine level in the blood to a person's age, weight, and sex. Determining creatinine clearance more precisely requires an accurately timed urine collection in conjunction with the blood creatinine determination. The level of blood urea nitrogen (BUN) can also indicate how well the kidneys are functioning, although many other factors can alter the BUN level.

Imaging Tests
Plain X-rays:
X-rays are usually not helpful in evaluating urinary tract disorders.

Ultrasonography:
Ultrasonography is often the initial imaging technique because it can be performed safely even when kidney function is impaired. It is noninvasive and painless and requires no radiopaque contrast agent. Ultrasound scans provide some indirect information about kidney function, are an excellent way to estimate kidney size and position, readily detect obstruction, and help diagnose structural abnormalities. Ultrasonography is not as accurate as computed tomography (CT) in the diagnosis of kidney tumors. Doctors also use ultrasonography to locate the best place for a kidney biopsy.
Urinary tract stones may be detected by ultrasonography, although stones smaller than about ¼ inch (5 millimeters) may be missed. When doctors suspect that the flow of urine from the bladder is obstructed, they sometimes use ultrasonography to measure the amount of urine that remains in the bladder after a person makes every effort possible to urinate.
Ultrasonography is not as accurate as CT in the diagnosis of bladder tumors.

Computed Tomography:
CT is used to evaluate kidney masses. Helical CT (sometimes called spiral CT), performed by continuously moving the person through the CT scanner, permits special images of certain structures and more rapid completion of the scanning process. Helical CT without the use of a radiopaque contrast agent is useful for people who may have kidney stones or for people who have suffered trauma in whom bleeding into the kidney or surrounding tissues must be identified rapidly. Radiopaque contrast is often used in CT examinations. The intravenous contrast agent provides extra detail about the kidney arteries and veins, about certain kidney tumors (such as renal cell cancer), and about polycystic kidney disease. Use of contrast agents may result in allergic-type reactions or, rarely, kidney damage.

Magnetic Resonance Imaging:
MRI can provide three-dimensional images of the kidneys, blood vessels, and structures surrounding the kidneys. MRI helps distinguish tumors from cysts. When used with a paramagnetic contrast agent to enhance images, MRI can identify disorders of kidney blood vessels. People who require evaluation of the kidney blood vessels and who are at risk for reactions to radiopaque contrast agents can undergo MRI rather than CT.

Intravenous Urography:
Intravenous urography (IVU, also called intravenous pyelography or IVP) uses a radiopaque contrast agent given through a vein to provide an x-ray image of the kidneys, ureters, and bladder. Usually, an ultrasound, CT scan, or MRI scan is done instead. However, IVU can better detect small abnormalities of the ureters and some abnormalities of the kidneys. IVU is often done for people with blood in the urine, even if the blood is not visible to the naked eye. It is also often done for people who doctors suspect may have cancer involving the ureters or other urinary passages. Use of contrast agents may result in allergic-type reactions or, rarely, kidney damage.

Cystourethrography:
In cystourethrography, a radiopaque contrast agent similar to that used in intravenous urography is injected directly through a scope or catheter passed through the urethra and into the bladder. When x-ray films of the bladder and urethra are taken during and immediately after urination, the study is called a voiding cystourethrogram, which is especially useful in evaluating recurring urinary tract infections. Cystourethrography may result in infection. Use of contrast agents may result in allergic-type reactions or, rarely, kidney damage.

Radionuclide Scanning:
A radionuclide scan of the kidneys is an imaging technique that relies on the detection of small amounts of radiation by a special gamma camera after the injection of a radioactive chemical. One type of radionuclide study assesses kidney blood flow (renogram). Radionuclide scans are useful in evaluating other kidney problems.

Angiography:
Angiography involves injecting a radiopaque contrast agent into an artery. Because it involves inserting a catheter into an artery and injecting the contrast agent under high pressure, angiography has higher risks than all other kidney imaging procedures. Thus, angiography is reserved for special situations (such as prior to balloon angioplasty and following angioplasty for the placement of a stent) to hold one of the kidney arteries open or to provide detailed information about the kidney arteries before kidney surgery. Complications of angiography may include injury to the injected arteries and neighboring organs, bleeding, and reactions to radiopaque contrast agents.

Cystoscopy
A doctor can diagnose some disorders of the bladder and urethra by looking through a flexible viewing tube (cystoscope, a type of endoscope). A cystoscope, which has a diameter about the size of a pencil, may be between 1 and 5 feet (30 to 150 centimeters) in length, but only 6 to 12 inches (about 15 to 30 centimeters) of the scope are inserted into the urethra and bladder. Most contain a light source and a small camera, which allows the doctor to view the inside of the bladder and urethra. Many cystoscopes also contain a small clipping device on the tip, allowing the doctor to obtain a sample (biopsy) of the bladder lining. Cystoscopy can be done while a person is awake and causes only minor discomfort. The doctor usually inserts an anesthetic gel into the urethra before the procedure. Possible complications include bleeding in the urine and, rarely, perforation of the bladder.

Tissue and Cell Sampling
Kidney Biopsy: A kidney biopsy (in which a sample of kidney tissue is removed and examined under a microscope) is primarily used to help the doctor diagnose disorders that affect the specialized blood vessels of the kidney (glomeruli) and tubules and unusual causes of acute kidney failure. A biopsy is often performed on a transplanted kidney to look for signs of rejection.
When undergoing a kidney biopsy, the person lies face down, and a local anesthetic is injected into the skin and muscles of the back over the kidney. Ultrasonography or CT is used to locate the part of the kidney where the glomeruli are located and to avoid large blood vessels. The biopsy needle is inserted through the skin and into the kidney.
This procedure is not recommended for anyone with uncontrolled high blood pressure, bleeding disorders, active urinary tract infection, or only one kidney (except for a transplanted kidney). Complications include bleeding into the urine around the kidney and formation of small arteriovenous fistulas (abnormal connections between very small arteries and veins) within
the kidney.

Urine Cytology:
Urine cytology, microscopic examination of the urine to look for cancer cells, is sometimes useful in diagnosing cancers of the kidneys and urinary tract. For people at high risk-for example, smokers, petrochemical workers, and people with painless bleeding-urine cytology may be used to screen for cancer. For people who have had a bladder or kidney tumor removed, the technique may be used for follow-up evaluation. However, the results can sometimes indicate cancer when none is present, or they can fail to indicate cancer when it is present, especially if the cancer is very new or slow growing.

Symptoms
Some urinary tract disorders rarely cause symptoms until the problem is very advanced; these include kidney failure, tumors and stones that do not block urine flow, and some low-grade infections. Sometimes, symptoms occur but are very general and difficult for the doctor to connect to the kidney. For example, a general feeling of illness (malaise), loss of appetite, nausea, or generalized itching may be the only symptoms of chronic kidney failure. In older people, mental confusion may be the first recognized symptom of infection or kidney failure. Symptoms that are more suggestive of a kidney or urinary problem include pain in the side (flank), swelling of the lower extremities, and problems with urination.

Burning or Pain with Urination
Burning or pain with urination (dysuria) may be felt at the opening to the urethra or, less often, over the bladder (in the pelvis, the lower part of the abdomen just above the pubic bone). Occasionally, if a woman has vaginal irritation (for example, due to inflammation or infection of the vagina or of the area surrounding the vaginal opening, called vulvovaginitis) , she may feel a burning sensation when urinating.
Dysuria is very common, particularly among adult women, in whom it is often caused by urinary tract infections, such as cystitis and urethritis. However, dysuria can occur in men and women of any age and can have many noninfectious causes.
Doctors can sometimes get clues to the cause based on where symptoms are most severe. For example, if symptoms are most severe just above the pubic bone, a bladder infection (cystitis) may be the cause. Women with frequent episodes of cystitis may recognize characteristic symptoms that suggest another episode. If symptoms are most severe at the opening of the urethra, urethritis may be the cause. In men with a penile discharge, urethritis is often the cause. If burning affects mainly the vagina and the woman has a discharge, vaginitis may be the cause.
Examination may confirm a condition that could be causing dysuria. For example, vaginal or penile discharge can be confirmed. Inflammation or atrophy of the vagina or vulva may confirm vulvovaginitis. An enlarged prostate may confirm benign prostatic hyperplasia. Tenderness of the epididymis or testes may suggest epididymo-orchitis, and tenderness of the prostate may suggest prostatitis.
Doctors do not always agree on the need for tests. Some doctors just treat adult women who have symptoms that suggest cystitis. Other doctors usually do testing for all people or for people in whom the diagnosis is not clear. The first test is usually a urinalysis. Urine culture is often done to identify the organism causing infection and to determine which antibiotics will be effective. For women, a sample of vaginal discharge is examined on a slide using a microscope. Men and women with a urethral discharge are tested for gonorrhea and chlamydia.
The cause is treated. Often, the cause is an infection, and treatment produces relief in 1 or 2 days. If dysuria is severe, phenazopyridine can be taken for the first 2 days to relieve discomfort. Phenazopyridine turns the urine a red-orange color.

Flank pain
Pain caused by kidney disorders usually is felt in the side (flank) or small of the back. Occasionally, the pain radiates to the center of the abdomen. Usually pain occurs because the kidney's outer covering (renal capsule) is stretched by a disorder that causes rapid swelling of the kidney. Severe kidney pain is often accompanied by nausea and vomiting. A kidney stone causes excruciating pain when it enters a ureter. The ureter contracts in response to the stone, causing severe, crampy pain (renal or ureteral colic) in the flank or lower back that often radiates to the groin or, in men, to the testis. The pain typically comes in waves. A wave may last 20 to 60 minutes and then stop. The pain stops without resuming again when the ureter relaxes or the stone passes into the bladder.
A kidney infection (pyelonephritis) produces swelling of the kidney tissue, which stretches the renal capsule, causing steady, aching pain. Kidney tumors do not usually cause pain until they have become very large. Other disorders that cause pain in the flank include acute blockage of blood flow to the kidney or intestine, ruptured and occasionally unruptured abdominal aortic aneurysms, problems with the spine or spinal nerves, musculoskeletal injuries, and tumors that involve the back of the abdomen (retroperitoneum) .
After noting symptoms, the doctor examines the person and usually obtains a urinalysis to check for red blood cells or excess white blood cells, which suggest an infection, and a urine culture when appropriate. A person with very severe, colicky pain and blood in the urine is very likely to have a kidney stone. A person with milder, steady pain, tenderness when the doctor taps over one kidney, fever, and excess white blood cells in the urine is likely to have a kidney infection. If a kidney stone is suspected, the doctor usually obtains a computed tomography (CT) scan to determine the size and location of the stone and whether it significantly obstructs urine flow.
An intravenous contrast agent is not used for this CT scan. If the doctor is not sure of the cause of pain, often a CT scan that uses an intravenous contrast agent or another imaging test is done.
The underlying disorder is treated. Mild pain can be relieved by taking paracetamol/ acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Pain from kidney stones may be severe and may require use of intravenous opioids.

Swelling
Swelling results from accumulation of fluid in the tissues (edema). The swelling may cause weight gain. Swelling is usually most noticeable in the ankles and feet, but it may also involve the abdomen, lower back, hands, and face. If swelling is particularly severe, fluid may accumulate in the lungs, causing difficulty breathing.
Swelling may occur if the kidneys are unable to excrete excess water and sodium from the body, as in kidney failure. Swelling may also develop from a kidney disorder that causes the loss of large amounts of blood protein (especially albumin) in the urine (nephrotic syndrome). When the albumin level in the blood drops sufficiently, swelling occurs as fluid leaks from the circulation into the tissues.
Other disorders may also cause swelling. Heart failure, caused by inadequate pumping by the heart, signals the kidneys to retain salt and fluid, which may accumulate in tissues. Advanced liver disease also signals the kidneys to retain salt and fluid; swelling is worsened by the reduction in blood protein that occurs. This protein decrease causes fluid to leak into the tissues. If swelling occurs in only one limb, the cause is probably something related to the limb (such as a blood clot in a vein or an injury) rather than a kidney, heart, or liver problem.
Doctors usually assess the presence and degree of swelling by pressing on the person's shins. If the skin retains the impression of the doctor's finger, extra fluid is present. The person's symptoms and the doctor's physical examination suggest whether the kidneys, liver, or heart is the cause, but doctors also obtain a urinalysis and blood tests of liver and kidney function. If heart failure is suspected, a chest x-ray and sometimes an echocardiogram are obtained. To diagnose nephrotic syndrome, doctors may assess urinary loss of protein by calculating the ratio of total protein to creatinine in a urine specimen.
The underlying disorder is treated when possible. Swelling can often be relieved by a diuretic if the kidneys are working properly. If the kidneys are not working properly and fluid has collected in the lungs, the person may need dialysis.

Increased Urination
Most people urinate about 4 to 6 times a day, mostly in the daytime. Normally, adults pass between 3 cups (700 milliliters) and 2 quarts (2 liters) of urine a day. Infants may pass as little as 1 cup (230 milliliters) per day. Urination can be increased if a person produces an excess volume of urine or produces a normal volume of urine but feels the need to go more often (urinary frequency).

Increased Volume:
Excess urine can be caused by drinking too much fluid (polydipsia) , by taking diuretic drugs or substances that have a diuretic effect, such as alcohol or caffeine, or by having a high level of sugar in the blood (as in diabetes mellitus). A rare condition called diabetes insipidus causes excess urine because of problems with a brain hormone called antidiuretic hormone (also called vasopressin) . Antidiuretic hormone helps the kidney reabsorb fluid. If too little antidiuretic hormone is produced (a condition called central diabetes insipidus) or if the kidney is unable to properly respond to it (nephrogenic diabetes insipidus), the person urinates excessively.
Increased Frequency: A frequent need to urinate without an increase in the total daily output of urine can occur when something irritates or presses on the bladder. A urinary tract infection (UTI) is the most common cause of bladder irritation. Rarer causes include a stone or tumor in the bladder. A tumor or other mass (or even the uterus if a woman is pregnant) pressing on the outside of the bladder can also cause a frequent urge to urinate because the mass reduces the capacity of the bladder. An inability to fully empty the bladder because of partial obstruction, often from an enlarged prostate (in men), can produce frequency.
The doctor asks about the use of diuretics. Symptoms such as pain or burning may indicate infection. For men, the doctor will examine the prostate by putting a gloved, lubricated finger in the man's rectum. If the prostate is enlarged, a blood test (prostate specific antigen, or PSA, test) and sometimes a prostate ultrasound are done. The doctor usually checks the urine for glucose (suggesting diabetes mellitus) and bacteria or excess white blood cells (indicating infection). If the cause is not clear, the doctor may measure levels of electrolytes in the blood and urine and sometimes perform imaging tests of the kidney, ureters, or bladder (such as CT, ultrasound, or magnetic resonance imaging [MRI]). Treatment is directed at the underlying disorder.

Urinating at Night
Needing to urinate during the night (nocturia) is more common among older people. It can contribute to sleep problems and to falls, especially if a person is rushing to the bathroom or if the area is not well lit. Nocturia may occur in the early stages of many kidney disorders. Nocturia is also common in people with heart failure, liver failure, poorly controlled diabetes mellitus, or diabetes insipidus. A person may have nocturia if the kidneys cannot concentrate urine normally. Frequent urination of very small amounts at night may result when the flow of urine into and through the urethra is obstructed and urine backs up in the bladder. An enlarged prostate is the most common cause of obstruction in older men. Sometimes, however, the cause of nocturia may simply be drinking a large amount of fluids, especially alcohol or caffeinated beverages (such as coffee or tea) in the late evening.
Bed-wetting (enuresis) is normal in young children. After about age 5 or 6, it may indicate a delay in the maturation of the muscles and nerves of the lower urinary tract, which most often resolves without treatment. If bed-wetting persists, other causes are considered, such as UTI, diabetes, inadequate control of the nerves of the bladder, or psychologic causes. The cause of nocturia is often evident from the person's symptoms and the results of the examination. In men, doctors examine the prostate. Testing may be needed, depending on what possible causes are suspected. Treatment is directed at the underlying disorder. In all people, minimizing intake of fluids, alcohol, and caffeinated beverages during the late evening and voiding immediately before going to bed may help limit nocturia.

Hesitating, Straining, and Dribbling
A hesitating start when urinating, a need to strain, a weak and trickling stream of urine, and dribbling at the end of urination are common symptoms of a partially obstructed urethra. In men, these symptoms are caused most commonly by an enlarged prostate that compresses the urethra and less often by a narrowing (stricture) of the urethra. Similar symptoms in a boy may mean that he was born with an abnormally narrow urethra or has a urethra with an abnormally narrow external opening. The opening may also be abnormally narrow in women.
A doctor examines the prostate by inserting a gloved, lubricated finger into the man's rectum. If the prostate is enlarged, a blood test to measure the PSA level and sometimes a prostate ultrasound are obtained. If a urethral stricture is suspected, the doctor may insert a flexible viewing tube into the bladder (cystoscopy) .
To treat an enlarged prostate, drugs or surgery can be used. To treat a urethral stricture in a man, doctors may insert a catheter into the bladder through the penis and perform dilation (stretching the urethra). It may be necessary to insert a hollow tube to hold the urethra open (a stent). Surgeons may rebuild the urethra or perform other surgical treatments.

Urgency
A compelling need to urinate (urgency), which may feel like almost constant painful straining (tenesmus), can be caused by bladder irritation. Incontinence may occur if a person does not urinate immediately. Urgency may be caused by a bladder infection. Caffeine and alcohol use may contribute to urgency but rarely cause severe urgency by themselves. Rarely, a poorly understood inflammation of the bladder (interstitial cystitis) is the cause. Doctors can usually determine the cause of urgency by the person's symptoms, the results of the physical examination, and urinalysis. If infection is suspected, urine culture may be needed. Sometimes, particularly if interstitial cystitis is suspected, cystoscopy and bladder biopsy are necessary. Treatment is directed at the underlying disorder.

Incontinence
An uncontrollable loss of urine (incontinence) can have a variety of causes.

Blood in the Urine
Blood in the urine (hematuria) can make the urine appear red or brown, depending on the amount of blood, how long it has been in the urine, and how acidic the urine is. An amount of blood too small to turn the urine red may be detected by chemical tests or microscopic examination.
Blood in the urine may be caused by infection, stones, tumors, injuries, or other problems in the bladder, urethra, ureters, or kidneys. About half of the people who have blood in the urine without pain have a disorder affecting primarily certain specialized blood vessels of the kidney (glomeruli). Sometimes, sickle cell anemia or a related disorder is the cause. Blood in the urine with pain is often the result of a kidney, bladder, or prostate infection or a stone or a blood clot moving through one of the ureters or the urethra.
Sometimes, a diagnosis can be made on the basis of the person's symptoms and the results of the doctor's physical examination, urinalysis, and, if infection is suspected, urine culture. Often, however, cystoscopy, imaging studies (such as CT, ultrasound, or MRI), or other tests are needed. If a tumor is suspected, urine is examined for tumor cells. A blood test for sickle cell anemia may be needed for people of African descent who are not known to have the disease. Treatment is directed at the underlying disorder.

Gas in the Urine
Passing gas (air) in the urine, a rare symptom, usually indicates an abnormal connection (fistula) between the urinary tract and the intestine, which normally contains gas. A fistula may be a complication of diverticulitis, other types of intestinal inflammation, an abscess, or cancer. A fistula between the bladder and the vagina may also cause gas to escape into the urine. Rarely, certain bacteria in the urine may produce gas.
Doctors perform a pelvic examination in affected women. To diagnose fistulas, doctors may perform cystoscopy, sigmoidoscopy, or both and obtain imaging studies, such as CT, MRI, or ultrasound. Fistulas are usually repaired surgically.

Changes in the Urine's Color
Normally, dilute urine is nearly colorless. Concentrated urine is deep yellow. Colors other than yellow are abnormal. Food pigments can make the urine red, and drugs can produce a variety of colors: brown, black, blue, green, orange, or red. Brown urine may contain broken-down hemoglobin (the protein that carries oxygen in red blood cells).
Broken-down hemoglobin can leak into the urine when bleeding occurs in the kidney, ureter, or bladder, or it can be excreted into the urine as the result of certain disorders that damage or destroy red blood cells (hemolytic anemia). Brown urine may contain muscle protein (myoglobin), which is excreted into the urine after severe muscle injury. Urine may be red because of pigments caused by porphyria, or black because of pigments produced by melanoma. Cloudy urine suggests the presence of excess white blood cells from a UTI, the presence of crystals of salts from uric acid or from phosphoric acid, or the presence of a vaginal discharge.
Doctors usually can identify the cause of an abnormal color by examining the urine under a microscope or by performing chemical tests. Treatment is unnecessary except if needed to treat the underlying disorder.

Changes in the Urine's Odor
The odor of urine can vary and does not usually indicate a disorder except in people who have certain rare metabolic disorders.
[Merck]