Section 11. Kidney and Urinary Tract Disorders

Chapter 142. Symptoms and Diagnosis of Kidney and Urinary Tract Disorders

Topics: Introduction | Symptoms | Diagnosis

Symptoms

Symptoms of urinary tract disorders often provide important clues to doctors. However, some urinary tract disorders, including infection, stones, urinary tract obstruction, and tumors, may be present even when the person does not have symptoms. Chronic kidney failure, in particular, produces no symptoms until the disease has progressed to an advanced stage. The first symptom is often a general feeling of illness (malaise), or loss of appetite, which may lead to weight loss. In older people, mental confusion may be the first recognized symptom.

Fever

Fever can be a symptom of kidney inflammation (nephritis) or kidney stones due to infection. A bacterial infection of the kidney (pyelonephritis) almost always causes a high fever. Kidney cancer sometimes causes fever. A bladder infection (cystitis) rarely causes a fever unless complicated by stones or obstruction.

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 because of a disorder that produces swelling of the kidney tissue.

A kidney stone causes excruciating pain when it enters a ureter. The ureter contracts in response to the stone, causing severe, crampy pain (renal colic) in the lower back, often radiating to the groin. The pain stops when the ureter relaxes or once the stone passes into the bladder.

Pain in the bladder is most often caused by a bacterial infection. The discomfort is usually felt above the pubic bone and at the outer end of the urethra while the person is urinating. Blocked urine outflow causes pain above the pubic bone. However, a blockage that develops slowly may enlarge the bladder painlessly.

Fatigue, Nausea, Vomiting, and Itching

Fatigue, nausea, vomiting, and overall itching of the skin commonly develop in people who have kidney failure. These symptoms result from the accumulation of metabolic waste, including acids, which the diseased kidneys are unable to excrete. Fatigue may also result from decreased production of red blood cells, a frequent problem in chronic kidney failure.

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.

Swelling may occur if the kidneys are unable to excrete excess water and sodium from the body. Swelling may also develop from a kidney disorder that causes the loss of large amounts of 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.

Problems With Urination

Most people urinate about 4 to 6 times a day, mostly in the daytime. Normally, adults pass about 3 cups to 2 quarts of urine a day. Infants may pass as little as 1 cup per day.

Frequency: Anything that increases urine production, such as diuretics and a high level of sugar in the blood, can cause frequency. A frequent need to urinate without an increase in the total daily output of urine is a symptom of a urinary tract infection (UTI) or of something irritating the bladder, such as a stone or tumor. A tumor or other mass 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, can produce frequency.

Changes in Output: A kidney disorder can impair the kidney's ability to concentrate urine, increasing the daily output of urine. Very large amounts of urine are often a response to a high level of glucose (sugar) in the blood (as in diabetes mellitus), decreased production of antidiuretic hormone by the pituitary gland (diabetes insipidus), or the kidneys' lack of response to antidiuretic hormone (nephrogenic diabetes insipidus).

Certain kidney disorders (such as kidney failure) and urinary tract disorders (such as obstruction of both ureters, an obstruction of the outlet of the bladder, or an obstruction of the urethra) may cause the daily output of urine to suddenly decrease to less than 2 cups a day. A persistently reduced output of less than about 1 cup of urine a day leads to the buildup of metabolic wastes in the blood (azotemia).

Urinating at Night: In the early stages of many kidney disorders, a person may need to urinate frequently during the night (nocturia). 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 (see Section 21, Chapter 239). Sometimes, however, the cause of nocturia may simply be drinking a large amount of fluids, especially alcohol, 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 an infection or narrowing (stricture) of the urethra, inadequate control of the nerves of the bladder, or psychologic causes.

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.

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.

Incontinence: An uncontrollable loss of urine (incontinence) can have a variety of causes (see Section 11, Chapter 147).

Blood or Gas 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 without pain may be caused by problems in the bladder, urethra, ureters, or kidneys. Causes of blood in the urine that may or may not be accompanied by pain include kidney stones, kidney cysts, sickle cell disease, hydronephrosis, and cancer. Blood in the urine with pain is often the result of a kidney or bladder infection, or of a stone, or a blood clot moving through one of the ureters or the urethra.

Passing gas (air) in the urine, a rare symptom, usually indicates an abnormal connection (fistula) between the urinary tract and the intestine. 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, bacteria in the urine may produce gas.

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, or red. Brown urine may contain broken-down hemoglobin (the protein that carries oxygen in red blood cells), which is present if blood leaks into the urine from kidney, ureter, or bladder disease. Less commonly, broken-down hemoglobin may be present because of certain disorders, such as hemolytic anemia. Brown urine may contain muscle proteins 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 pus from a urinary tract infection or the presence of crystals of salts from uric acid or from phosphoric acid. Doctors usually can identify the cause of an abnormal color with chemical tests or by examining the urine under a microscope.

Changes in the Urine's Odor: The odor of urine may provide clues about certain diseases and conditions. The odor is usually stronger if the urine is more concentrated, as occurs in dehydration. The urine may smell foul in a person who has a bacterial infection of the kidneys or the urinary tract. The urine may smell sweet in a person with uncontrolled diabetes mellitus. The urine may smell musty in a child with phenylketonuria (see Section 23, Chapter 274).