Diplomate, Board Certification of Emergency Medicine
Chairman, Department of Emergency Medicine Ma'ayenei Hayeshua
Hospital
Our next series concerns the kidneys and urinary tract. Of
course, there are topics in urology that are not appropriate
for public discussion so feel free to write me if you have
any private questions.
What we eat and what gets absorbed through our skin is often
toxic. Furthermore, our cells produce byproducts that also
must be excreted. Materials that are soluble in water are
dealt with by the kidney. Non-water- soluble ones are dealt
with by the liver.
The blood goes through the kidneys continuously, and there
filters deal with these poisons. The kidney also maintains
electrolyte and fluid balance. If you drink too much, then
your kidneys will excrete more salt, bringing water with it.
Potassium, magnesium, calcium and other ions are also dealt
with here. Acid-base balance is done here too. Furthermore,
the kidneys are responsible for the secretion of the hormones
for making blood. We see what an important organ this is.
Once the urine has been formed and appropriately
concentrated, it goes through a bigger tube called the renal
pelvis and then into the ureter -- a long tube that drains
into the bladder. The bladder then stores the urine until
such time as it can be excreted. Note that once the urine
leaves the kidney, its components cannot be changed.
Before we focus on the kidney and diseases affecting it, let
us speak about how we study the kidney. The easiest way is by
urinalysis. With the dip of a small stick we can see
infection, concentration of the urine, invisible blood,
protein, sugar, and acids. Inappropriate concentrating of
urine can be a sign of kidney failure, or SIADH/diabetes
insipidus. The last two are diseases that make the sodium
concentration too low or too high.
The presence of blood can be sign of muscle injury, kidney
disease, kidney stones, cancer, or trauma. Protein can be a
sign of kidney disease. Sugar can be a sign of diabetes, but
can also be a result of eating a very sugary meal. Acids in
the urine can be a sign of diabetes gone bad.
Urine under a microscope can show us infection, blood or
signs of crystals that can be kidney failure as well. Urine
electrolytes can tell us the status of the kidneys and help
us know if a patient is dehydrated or truly with kidney
disease. The best test is a 24 hour collection of urine which
gives us the most information. Blood tests of urea and
creatinine -- two substances excreted by the kidney -- allow
us to know the level of kidney failure, although measuring pH
and potassium must be done to make sure a dangerous situation
does not exist.
Kidney function can also be measured by a nuclear scan.
Structural problems once were investigated by an IVP, a dye
study with x-ray, but this has largely been supplanted by CT.
Ultrasound can give some detail as well, but it is inferior
to CT. More next week. Write me in care of the
Yated.
A message from Glaxo, sponsor of this column. The
American Association of Pediatrics has released their
guidelines on head lice, and Lyclear appears as a treatment.
Our particular form of head lice in Israel is a tough one to
deal with, but Lyclear can be effective. Works well for
scabies as well. This problem may be especially worrying in
the elderly.
