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Chief Compliant:
A 56-year-old lady with a prior renal stent and calculi presented
for renal evaluation prior to percutaneous nephrolithotomy
History of Present Illness:
Patient
has a history of kidney stones and had a ureteral stent placed in
the summer of 2006 when purulent urine was drained and she was
started on antibiotic therapy. She went for a second opinion in
September and at that time she appeared to have a heavy stone burden
in the right kidney and was referred for further management to UAMS.
Patient was informed she only had 28% right kidney function on this
visit.
Past Medical History:
hypertension,
diabetes, myocardial infarction, cardiac failure, partial
thyroidectomy in 1980, hepatitis A in 1959, lumpectomy for breast
benign mass, cholecystectomy in 1973.
Medications Prior to Admission: The patient is
currently on Plavix and aspirin (will be stopped 1 week prior to
percutaneous nephrolithotomy)
Allergies: Sulfa, Macrodantin and MSG
Physical Exam: BP: 147/70, wt: 253 pounds.
Radiology: Patient's KUB x-ray shows a
ureteral stent on the right side, calcified at the lower end. She
has a large stone burden within the right kidney and based on the
CT, it does appear that part of the ureteral stent is calcified. Due
to the large stone burden it is likely that she will need a
percutaneous nephrolithotomy and a cystoscopy will be performed to
remove the encrustation from the distal end of the stent and attempt
to remove the stent from below. A Lasix renogram was arranged to
confirm kidney function.
A lasix renogram was performed using 10.04
millicuries of technetium-99m MAG3 and 40 mg of Lasix. Dynamic
imaging was obtained of the kidneys in the posterior projection to
evaluate both the flow and the excretory phase after the
administration of Lasix. Curves were generated to measure the renal
functioning bilaterally.
There was prompt and equal flow to both kidneys with
the left being significantly larger than the right. Lasix was given
at 15 minutes at which time the left kidney had already started
emptying but the Lasix prompted the right kidney to start emptying.
Excretion occurred completely from both kidneys post Lasix. There
was evidence of a dilated right ureter present but no evidence of
obstruction.
The differential functioning was assessed to be 67%
on the left and 33% on the right, probably due to the size
difference between the kidneys.
Teaching Note:
Types of Kidney
Stones:
v
Calcium stones.
Roughly four out of five kidney stones are calcium stones. These
stones are usually a combination of calcium and oxalate. Oxalate is
a compound that occurs naturally in some fruits and vegetables. A
number of factors can cause high concentrations of these substances
in urine. Excess calcium, for instance, may result from ingesting
large amounts of vitamin D, from treatment with thyroid hormones or
certain diuretics, and from some cancers and kidney conditions. You
may also have high levels of calcium if your parathyroid glands,
which regulate calcium metabolism, are overactive
(hyperparathyroidism). On the other hand, certain genetic factors,
intestinal bypass surgery and a diet high in oxalic acid may cause
excess amounts of oxalate in your body.
v
Struvite stones.
Found more often in women than in men, struvite stones are almost
always the result of chronic urinary tract infections caused by
bacteria that produce specific enzymes. These enzymes increase the
amount of ammonia in the urine, which is incorporated in the
crystals of struvite stones. These stones are often large, may have
a characteristic stag's-horn shape and can seriously damage your
kidneys.
v
Uric acid stones.
These stones are formed of uric acid, a byproduct of protein
metabolism. You're more likely to develop uric acid stones if you've
undergone chemotherapy, you eat a high-protein diet or you have
certain genetic factors that predispose you to the condition.
v
Cystine stones.
These stones represent only a small percentage of kidney stones.
They form in people with a hereditary disorder that causes the
kidneys to excrete excessive amounts of certain amino acids (cystinuria).
Risk factors for kidney stones & treatment options
v
Dehydration
v
Family or personal history.
v
Age, sex and race.
Most people who develop kidney stones are between 20 and 70 years of
age. Men are more likely to develop kidney stones than are women. In
addition, white Americans are at higher risk of kidney stones than
are black Americans.
v
Certain diseases.
Rare, inherited diseases such as renal tubular acidosis and
cystinuria can increase your risk of kidney stones. So can more
common disorders such as gout, chronic urinary tract infections and
hyperparathyroidism.
v
Certain medications.
Medications can have variable effects on stone formation. For
example, diuretics may increase risk of developing kidney stones in
some situations and decrease it in others.
v
Diet.
A diet that's high in protein (meat, chicken and fish) and sodium
(salt), and low in whole grains and calcium may increase risk of
some types of kidney stones.
v
Limited activity.
Limited activity can cause bones to release more calcium and
increase risk for stone formation
Treatment for kidney stones varies, depending on the
type of stone and the cause. Patients may be able to move a stone
through the urinary tract simply by drinking plenty of water but
many may need more invasive treatments.
v
Extracorporeal shock wave lithotripsy (ESWL).
This is a commonly used procedure for treating kidney stones. It
uses shock waves to break the stones into tiny pieces that are then
passed in the urine.
v
Percutaneous nephrolithotomy.
When ESWL isn't effective, or the stone is very large, this surgical
procedure is used. A surgeon removes the kidney stone through a
small incision in the back using an instrument called a nephroscope.
v
Ureteroscopic stone removal.
This procedure may be used to remove a stone lodged in a ureter. The
stone is snared with a small instrument (ureteroscope) that's passed
into the ureter through the bladder. Ultrasound or laser energy can
also be directed through the scope to shatter the stone. These
methods work especially well on stones in the lower part of the
ureter.
v
Parathyroid surgery.
Some calcium stones are caused by overactive parathyroid glands,
which are located on the four corners of the thyroid gland. When
these glands produce too much parathyroid hormone, the body's level
of calcium can become too high
BACK
© 2007 Nuclear Education Online
Case study contributed by Amanda Galiano, PharmD
candidate, UAMS
- Images courtesy of University
of Arkansas for Medical Sciences Dept of Nuclear Medicine.
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