the KIDNEYS. Among those most commonly associ-
ated with altered kidney function and RENAL FAIL-
UREare
- heavy metals such as lead, mercury, cadmium,
and arsenic; exposure to these metals is most
often occupational - NONSTEROIDAL ANTI-INFLAMMATORY DRUGS(NSAIDS)
such as ibuprofen, naproxen, and ketoprofen - possibly acetaminophen
- Contrast dyes used in radiologic procedures
- certain ANTIBIOTIC MEDICATIONS, notably strepto-
mycin and gentamicin - organic solvents such as benzene
People who already have compromised kidney
function or conditions such as DIABETESor HYPER-
TENSION(high BLOOD PRESSURE) are at greater risk
for kidney damage resulting from nephrotoxins.
Chronic DEHYDRATION, such as may occur with
diuretic therapy or insufficient water consump-
tion, increases the risk for kidney damage result-
ing from medications, especially NSAIDs.
See also HEPATOTOXINS; NEPHRON; NEPHROPATHY.
neurogenic bladder A condition in which the
nerves that control the BLADDERdo not work prop-
erly, allowing the bladder to be underactive
(hypotonic) or overactive (spastic). Damage may
occur to the SPINAL CORD AND SPINAL NERVES, BRAIN,
orPERIPHERAL NERVESthat serve the bladder. Condi-
tions that can cause such damage include trau-
matic injury, STROKE, degenerative neurologic
disorders such as MULTIPLE SCLEROSISand PARKIN-
SON’S DISEASE, NEUROPATHYof DIABETESand neuropa-
thy of HIV/AIDS, and injury to the nerves of the
bladder as a consequence of pelvic surgery (such
as PROSTATECTOMY in men or HYSTERECTOMY in
women). URINARY INCONTINENCEis the most com-
mon consequence of neurogenic bladder.
The diagnostic path includes urinalysis, BLOOD
tests, and diagnostic imaging procedures such as
CYSTOSCOPY, ULTRASOUND, or COMPUTED TOMOGRAPHY
(CT) SCAN. The urologist may also perform a void-
ing CYSTOURETHROGRAM to evaluate the flow of
URINE through the urinary system. Electromyo-
gram (EMG) measures the response of the nerves
and muscles of the bladder and urethra to mild
electrical stimuli. Other tests can measure the
capacity and rate of emptying of the bladder.
Treatment targets the underlying cause of the
neurogenic bladder when possible. Other treat-
ment measures aim to improve urinary inconti-
nence. The success of the treatment often depends
on the underlying cause. Various medications may
increase or decrease the bladder’s responses.
Surgery is sometimes an option. Though it may
take time and much trial and error, most people
find acceptable measures for accommodating neu-
rogenic bladder.
See also SPINAL CORD INJURY; TRAUMATIC BRAIN
INJURY(TBI); URINARY TRACT INFECTION(UTI).nocturia The need to get up from nighttime
sleep to urinate. Nocturia is a significant cause of
SLEEP DISORDERSthough has numerous potential
causes. Nocturia becomes more common with
increasing age in both women and men, some-
times simply as a consequence of normal age-
related changes that occur in the urinary tract.
Key among these changes is the reduced ability of
the BLADDER to distend because lost elasticity in
the tissues, effectively shrinking the bladder’s
capacity.
Many people are unaware how much fluid
they drink in the evening. The urinary system is
still processing all this fluid when the person lies
down to go to bed. Often, simply changing habits
to minimize fluid consumption after dinner is
enough to slow URINE production through the
night. When nocturia persists despite such meas-
ures, the urologist may prescribe medications such
as tolterodine or oxybutynin that slow the blad-
der’s response.CONDITIONS FOR WHICH
NOCTURIA IS A COMMON SYMPTOM
BENIGN PROSTATIC HYPERPLASIA(BPH) CYSTITIS
CYSTOCELE HYDRONEPHROSIS
NEPHROLITHIASIS NEUROGENIC BLADDER
PROSTATITIS URINARY TRACT INFECTION(UTI)
UROLITHIASIS VAGINITISSee also AGING, URINARY SYSTEM CHANGES THAT
OCCUR WITH; ENURESIS; URINARY INCONTINENCE.212 The Urinary System