Encyclopedia of Health and Medicine

hypospadias 197
Other causes of hypercalciuria include
endocrine disorders such as HYPERPARATHYROIDISM
and ADDISON’S DISEASE, kidney dysfunction, and
MALABSORPTION disorders of the gastrointestinal system.
Many people who have hypercalciuria do not
have nephrolithiasis or urolithiasis, though the
presence of excess calcium in the urine raises their
risk for developing either condition. Routine urinalysis
often detects hypercalciuria. Doctors generally
recommend increased water consumption,
maintaining dietary calcium intake at recommended
levels for BONE health, and daily physical
activity. Many people also benefit from thiazide
diuretic medications, which act to slow the extraction
of calcium in the kidneys as well as to
increase the volume of urine. Many stones that
form as a consequence of hypercalciuria will pass
through the urinary tract without medical intervention,
though they require treatment when
they cause significant pain or an obstruction in the
kidney, URETER, bladder, or URETHRA.
See also CYSTINURIA; FANCONI’S SYNDROME; HYPER-
OXALURIA; RENAL TUBULAR ACIDOSIS.
hyperoxaluria Excessive OXALATE excretion in the
URINE. Oxalate is a natural chemical that enters the
body through dietary sources such as vegetables,
fruits, and grains. The LIVER also metabolizes
oxalate. Researchers do not know what benefits the
body derives from oxalate. However, in the body
oxalate attracts calcium, creating the insoluble
compound calcium oxalate. About 80 percent of
kidney stones are made of calcium oxalate.
Deposits of calcium oxalate may also accumulate in
tissues such as the KIDNEYS, liver, HEART, and bones,
a circumstance known clinically as oxalosis.
Most hyperoxaluria is idiopathic (without a
clearly identifiable cause). Doctors believe about
50 percent of people who have mild to moderate
hyperoxaluria consume an abundance of foods
high in dietary oxalate. In some people the binding
between calcium and oxalate intensifies for
reasons researchers do not understand though
believe results from genetic factors. Less commonly,
hyperoxaluria occurs as an autosomal
recessive genetic disorder that results in the
absence of an enzyme the body requires to break
down oxalate into soluble components that are
more easily excreted. Genetic hyperoxaluria generally
causes symptoms (typically kidney or
bladder stones) in early childhood. Rarely, hyperoxaluria
is a secondary complication of MALABSORP-
TION disorders, such as SHORT BOWEL SYNDROME and
INFLAMMATORY BOWEL DISEASE (IBD), that alter the
gastrointestinal tract’s absorption of dietary calcium
and oxalate.
The most common symptoms are kidney stones
(NEPHROLITHIASIS) or bladder stones (UROLITHIASIS).
The diagnostic path includes laboratory tests to
measure the levels of oxalate in the urine and the
BLOOD, analysis of any stones, and family history.
Dietary modifications (eating fewer foods with
high oxalate content) are often treatment enough
for mild idiopathic hyperoxaluria. Other therapeutic
approaches include medications to increase the
ability of the urine to dissolve calcium and oxalate
salts, magnesium and pyridoxine (vitamin B 6 )
supplementation, and increasing water consumption
to dilute the urine. Primary (genetic) hyperoxaluria
typically results in RENAL FAILURE by early
adulthood with the only definitive treatment
being KIDNEY TRANSPLANTATION.
See also ADDISON’S DISEASE; HYPERCALCIURIA;
HYPERPARATHYROIDISM; ORGAN TRANSPLANTATION; SUR-
GERY BENEFIT AND RISK ASSESSMENT.
hypospadias A CONGENITAL ANOMALY in which the
URETHRA is shorter than normal and exits along the
underside of the PENIS in a boy or into the VAGINA
in a girl. Though uncommon overall, hypospadias
is very rare in girls. In boys, CHORDEE (severely
curved penis) often accompanies hypospadias.
The preferred treatment is surgery to extend the
urethra to its normal length and path. In boys,
such surgery also includes correction of the
chordee. The surgery establishes normal URINATION
and, in boys, restores structural integrity to the
penis that will permit sexual function and FERTILITY
later in life. The urologist typically performs the
OPERATION when the child is between 6 and 12
months of age. More than 90 percent of such corrective
surgery produces a functionally and cosmetically
acceptable repair. Some children may
need more than one operation, notably boys in
whom the urethral opening is near the base of the
penis.
See also BIRTH DEFECTS; BLADDER EXSTROPHY; EPIS-
PADIAS.