Kidney stones
(also known as
renal calculi) are stones of varying sizes,
which form inside the kidneys, ureter, urinary bladder or the
urethra. The kidneys are situated at the back of the abdomen and
their function is to remove waste products from the blood and
from the body in the form of urine, which passes down a tube called
a ureter into the bladder.
If
the concentration of a particular mineral in the urine is too
high, crystals form which sometimes become kidney stone. Most
kidney stones are only the size of a grain of sand but some may
be large enough to fill the collection sack leading out of the
kidney.
Kidney
stones tend to form when the level of a particular substance in
the urine is too high. This can either happen because the body
produces too much of a substance due to a medical condition or
because the persons diet is too high in that particular mineral
therefore producing a higher concentration in the urine. Alternatively
if the urine is very concentrated a stone is most likely to be
produced. This is why a stone is most likely to occur in hot weather
or in people who do not drink much fluid.
Kidney
stones are not very common in children but however these stones
are being discovered now with increasing frequency amounting for
upto one in each 1000 childhood admissions. These stones are in
the kidney in two thirds of reported cases and in the ureter in
the remaining cases. Although urinary stones are uncommon in children
less than two years old, older children are at greater risk independent
of age and sex.
Symptoms: Very often it is
possible to have a kidney stone without it causing any symptoms
at all especially if it is lying stationary within the kidney.
They may be related to recurrent kidney infections. However if
a stone passes down the ureter towards the bladder it generally
causes a severe colicky pain in the back just above the ribs and
follows the course of the stone. Once the stone reaches the bladder,
the pain subsides. Stone blocking the flow of urine must be removed
(surgically or through sound/shock waves). Microscopic hematuria
(blood in urine) and abdominal pain are the presenting symptoms
in majority of the cases.
Causes:
Although primary hyperabsorption (increased absorption) of dietary
calcium is the most commonly detected metabolic abnormality in
children with urinary stones, other conditions including juvenile
rheumatoid arthritis, inflammatory bowel disease, hyperparathyroidism,
osteoporosis, gastrointestinal disorders and urinary tract infections
carry enhanced risk for stone formation.
Types
of stones: The types of minerals that create kidney
stones vary. Many are made from calcium in people who have a very
high calcium diet or who have a medical condition which causes
them to have high levels of calcium in their blood, such as hyperparathyroidism.
A substance called as oxalate can be found in some stones often
in people who have a diet high in spinach, nuts, etc. Uric acid
stones can occur as a result of gout or in certain metabolic disorders
(where there is too much uric acid in the blood). A very rare
component of kidney stones is a substance called cystine, which
in some people can be leaked in high quantities into the urine.
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