Encyclopedia of Health and Medicine

208 The Urinary System
Because the kidneys play key roles in regulating
BLOOD PRESSURE kidney disease that interferes with
such functions can result in HYPERTENSION (high
blood pressure), which requires treatment. The
doctor may recommend dietary changes to limit
sodium, protein, and water intake. Treatment for
lupus nephritis often includes IMMUNOSUPPRESSIVE
THERAPY.
Risk Factors and Preventive Measures
The primary risk factors for nephritis are the conditions
that can cause it. Nephrotoxins are generally
avoidable once the doctor identifies them as
responsible for the nephritis. Bacterial infections
nearly always migrate to the kidneys from elsewhere
in the body. Early and appropriate treatment
for the primary infection, particularly strep
throat, helps prevent the infection from spreading
to the kidneys.
See also GLOMERULONEPHRITIS; GLOMERULOSCLERO-
SIS; INHERITANCE PATTERNS; NEPHROPATHY; NEPHROTIC
SYNDROME.
nephrolithiasis The formation of calcifications
(also called calculi) in the KIDNEYS, usually called
kidney stones. Kidney stones are common, with
about 1 in 10 adults in the United States likely to
have at least one over the course of adulthood.
Some people pass kidney stones with little discomfort
and may not even be aware of them, though
for many people nephrolithiasis is extremely
painful and debilitating. Kidney stones may lodge
in the ureters or within the kidney, usually in the
renal pelvis or a structure within the renal
medulla called the calyx where the collection
tubules empty their URINE.
Kidney stones that block the flow of
URINE constitute a medical emergency
that may require immediate treatment.
About 75 percent of kidney stones are made of
calcium in combination with oxalate, phosphate,
or carbonate. Calcium oxalate stones are the most
common. About 10 percent of stones are made of
uric acid and occur most frequently in men who
have GOUT (a form of arthritis) or in people who
are undergoing CHEMOTHERAPY. Other stones may
form of cystine, an amino acid compound, or of
struvite, a compound of magnesium, ammonia,
and phosphate that tends to form in women who
have frequent bacterial urinary tract infections
(UTIs).
Symptoms and Diagnostic Path
Common symptoms of kidney stones include
• rapid onset of excruciating PAIN in the side
(flank) or back
• persistent or colicky (wavelike) ABDOMINAL PAIN
• NAUSEA and VOMITING
• URINARY FREQUENCY and URINARY URGENCY
• FEVER and chills
• NOCTURIA (urination at night)
• groin pain in men or women or testicular pain
in men
The diagnostic path may include abdominal X-
RAY, ULTRASOUND, OR COMPUTED TOMOGRAPHY (CT)
SCAN to detect the location of the stone. The doctor
may also choose to conduct an INTRAVENOUS PYELO-
GRAM (IVP) to assess the extent to which a stone is
blocking the flow of BLOOD or urine. Blood and
urine tests may show elevated levels of calcium,
uric acid, or oxalate.
Treatment Options and Outlook
Treatment for nephrolithiasis with severe pain
begins with analgesic medication, often narcotic,
to relieve the pain. Further treatment to move the
stone out of the urinary tract may include EXTRA-
CORPOREAL SHOCK WAVE LITHOTRIPSY (ESWL), a noninvasive
method that effectively disperses stones up
to 2 centimeters in diameter, or surgery such as
percutaneous lithotomy in which the nephrologist
uses laparoscopic surgery to snare and remove the
stone. Most urologists prefer to take a course of
watchful waiting with calculi that are not causing
symptoms or that appear small enough to be able
to pass through the urinary tract on their own,
often recommending increased water consumption
to increase the volume of the urine.
Kidney stones tend to recur, so often it is useful
to determine the stone’s composition, as this helps
the nephrologist or urologist assess appropriate
measures to reduce the risk for future stone formation.
The doctor will likely recommend strain-