By Martha A. Simpson, D.O., M.B.A.
Associate Professor of Family Medicine
Ohio University College of Osteopathic
A CONNECTION BETWEEN KIDNEY STONES AND
My friend recently had a kidney
stone. Now he says I shouldn’t drink
caffeinated beverages or I’ll get one, too.
I know lots of people who drink caffeine,
but he’s the only one I know with a kidney
stone. Is he right? What exactly is a kidney
stone, and what causes them?
Kidney stones are formed when minerals and
acid salts that are naturally present in
urine are out of balance with the amount of
fluid passing through the body. Thus, stones
sometime develop when urine is more
concentrated than it should be, causing
minerals and salts to crystallize and
combine. Normally, people drink enough fluid
to prevent his. However, dehydration, among
other, less common causes, can lead to the
formation of stones.
Different minerals in the body form kidney
stones. The most common type of stone is
primarily formed from calcium oxalate.
Oxalate is found in caffeinated beverages,
such as coffee, cola, and especially, tea.
It’s also found in many foods such as
chocolate, spinach and nuts. Consuming these
foods or beverages in very large amounts,
especially if you are not consuming enough
other liquids, may create the conditions for
kidney stones to form. Without knowing your
friend’s history, I can’t diagnose what type
of stone he had, but it may have been this
Another common type of stone is formed from
calcium phosphate. Struvite stones, which
often result from kidney infection, are
common, and uric acid stones, which are
associated with dehydration, excess protein
in the diet, and gout, are also fairly
Large stones can block the flow of urine
from the kidneys to the bladder, and can
cause severe pain in the lower back that can
radiate to the abdomen and into the groin.
Some people notice blood in their urine.
Kidney stones may also cause nausea,
vomiting and fever.
However, small stones often pass through the
urinary tract and exit the body without
Treatment usually involves a recommendation
to drink plenty of fluid to help pass the
stones, and medication is prescribed to
control pain. However, a medical procedure
is sometimes necessary to remove, or break
up, large stones.
One of these procedures called lithotripsy
uses “shock waves” to break up kidney
stones. Some stones that are very large or
“stuck” in the ureters, the tube that leads
from the kidney to the bladder, may need to
be removed through a moderately invasive
As often is the case, prevention is the best
treatment. Maintaining good hydration is key
to preventing the formation of kidney
stones. Water, ginger-ale, lemonade,
lemon-lime sodas and fruit juices are the
beverages of choice for this purpose. The
citric acid found in lemons and other citrus
fruits helps inhibit oxalate stone growth.
In fact, people who drink large amounts of
iced tea in the summer should add lemon
juice to their tea to decrease the risk of
developing calcium oxalate stones.
The bottom line is that most people with no
family history of kidney stones, if
conscientious about staying well hydrated,
can safely consume caffeinated beverages in
Family Medicine® is a weekly column. General
medical questions can be sent to Martha A.
Simpson, D.O., M.B.A., Ohio University
College of Osteopathic Medicine,
Communication Office, Athens, Ohio 45701, or
do not send letters asking Dr. Simpson to
diagnose a condition or suggest a treatment
plan. Medical information in Family
Medicine® is provided as an educational
service only and does not replace the
judgment of your personal physician, who
should be relied on to diagnose and
recommend treatment for your medical
conditions. Past columns are available
College of Osteopathic Medicine
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