Kidney Stone Symptoms and Detection
History is very important in evaluating kidney stone disease.
Family history of kidney
stones may indicate an increased propensity to
form stones. Also, patients with a history of Crohn’s
disease, colectomy, sarcoidosis, hyperparathyroidism, RTA,
and gout, have an increased incidence of stones. Medications
are also implicated in kidney stone formation and may include
acetazolamide, Vitamin C or ascorbic acid, calcium-containing
antacids, traimterine, acyclovir, and indinavir. Those who
have a diet high in protein from meat, fish, chicken, those
whose intake of salt (sodium chloride) is excessive, and those
who drink fluids high in oxalates such as tea and some soft
drinks may be at an increased risk of stone formation.
Physical examination may find a patient in obvious distress.
Often times the patients are unable to remain still, and trying
to find a position that will make them more comfortable. They
may be sweating, have a rapid heart rate, and rapid respirations.
Often times blood pressure is elevated due to the severe discomfort.
Fever is usually absent unless infection is present. During
the examination, it is not uncommon for the patient to have
sudden onset of nausea and vomiting. Tenderness to percussion
of the costovertebral angle is often present and it is not
unusual for bowel sounds to be hypoactive resulting in an
ileus with abdominal distention.
Laboratory
Evaluation
A urinalysis may provide an enormous amount of information.
Not only is blood detected, but pH of the urine may indicate
the type of stone present. Calcium oxalate stones are found
in acid urine with pH less than 6.0. Uric acid stones are found
in acid urine with pH less than 5.5. Calcium phosphate and struvite
stones develop in alkaline urine with a pH greater than 7.2. If
white blood cells are noted in the urine, an infection may
be indicated. Also, if microscopic evaluation is carried out,
crystals may be identified. Cystine crystals are hexagonal,
calcium phosphate crystals are shaped like a coffin lid, and
uric acid crystals are rhomboidal.
If bacteria and white blood cells are present in the urine,
a urine culture may be obtained to identify the exact type
of bacteria present and their susceptibility to antibiotics.
Blood tests may show an increase in the white blood cell
count. If there is mild elevation, there may be no infection
but an extremely high white count may indicate serious infection.
Sometimes the infection may enter the blood stream-causing
what is called urinary sepsis, in this case there is usually
high fevers and shaking chills.
Blood chemistry tests are usually done for calcium, phosphate,
uric acid, sodium, potassium, chloride, bicarbonate, albumin,
and creatinine. If the serum calcium level is elevated, then
a test for hyperparathyroidism is performed by obtaining an
intact parathyroid hormone test.
A twenty-four hour urine collection is performed once the
acute episode is over. This checks total urine volume, pH,
calcium, oxalate, uric acid, citrate, magnesium, phosphate,
sodium, and creatinine. Cystine may also be checked if one
suspects cystinuria.
A kidney stone analysis is also performed to identify all the crystalline
components. As has been stated previously, the stones may
be made of , calcium oxalate, calcium phosphate, combination
of these two, struvite, uric acid, cystine, or secondary to
drug metabolite. |
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| X-ray Evaluation
KUB
A KUB is a plain film of the abdomen with the letters standing
for Kidneys-Ureters-Bladder. Approximately, 85% of kidney stones
can be identified with the KUB. Most kidney stones have a calcium
component and can be seen on the KUB. Only uric acid is truly
radiolucent, that is, can’t be seen on the KUB. It’s
a quick, inexpensive x-ray that can often tell the size and
number of stones present. Small stones less than 2mm may not
be identified and uric acid stones definitely cannot be seen.
IVP
IVP stand for intravenous pyelogram. IV contrast is injected
and several films are obtained as the contrast moves through
the kidneys and ureters to the bladder. An IVP is very reliable
at detecting stones and obstruction. It can often identify
uric acid stones or filling defects in the contrast and can
also identify obstruction. It does have drawbacks in that
some people are allergic to IV contrast and it shouldn’t
be used in patients with poor renal function.
Ultrasound
Ultrasonography can be used in patients with an allergy to
IV contrast, and is also useful in pregnancy, since there
is no radiation to the patient or fetus. It is very good at
picking up obstruction to the kidney. Small kidney stones, however,
that are not obstructing may be missed. |
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