C h a p t e r 2 5
Disorders of Renal Function
629
(UTIs) and is believed to result from congenital defects in
length, diameter, muscle structure, or innervation of the
submucosal segment of the ureter. Vesicoureteral reflux
is discussed further in Chapter 27.
The onset of acute pyelonephritis is usually abrupt,
with shaking chills, moderate to high fever, and a con-
stant ache in the loin area of the back that is unilateral
or bilateral.
5,21,22
Lower urinary tract symptoms, includ-
ing dysuria, frequency, and urgency, also are common.
There may be significant malaise, and the person usu-
ally looks and feels ill. Nausea and vomiting may occur
along with abdominal pain. Palpation or percussion
over the costovertebral angle on the affected side usually
causes pain. Pyuria occurs but is not diagnostic because
it also occurs in lower UTIs.
A second and infrequent form of acute pyelonephri-
tis is characterized by ischemia and a condition known
as
papillary necrosis
, the suppurative necrosis of one or
several renal pyramids.
4,5
It occurs most commonly in
persons with diabetes mellitus who develop acute pyelo-
nephritis when there is significant urinary tract obstruc-
tion. The development of papillary necrosis is associated
with a much poorer prognosis. There is often evidence
of overwhelming sepsis with frequent development of
kidney failure.
Acute pyelonephritis is treated with appropriate anti-
microbial drugs. Unless obstruction or other compli-
cations occur, the symptoms usually disappear within
several days. Treatment with an appropriate antimicro-
bial agent usually is continued for 10 to 14 days. Persons
with complicated acute pyelonephritis and those who
do not respond to outpatient treatment may require
hospitalization.
22
Chronic Pyelonephritis and Reflux
Nephropathy
Chronic pyelonephritis represents a progressive process.
There is scarring and deformation of the renal calyces
and pelvis, along with atrophy and thinning of the over-
lying cortex
4,5
(Fig. 25-12). The disorder involves a recur-
rent or persistent bacterial infection superimposed on
urinary tract obstruction, urine reflux, or both. Chronic
obstructive pyelonephritis can be bilateral, caused by
conditions that obstruct bladder outflow; or unilateral,
such as occurs with ureteral obstruction. Reflux, which
is the most common cause of chronic pyelonephritis,
results from superimposition of infection on congenital
vesicoureteral reflux or intrarenal reflux.
The symptoms of chronic pyelonephritis may be simi-
lar to those of acute pyelonephritis, or its onset may be
insidious. Often there is a history of recurrent episodes
of UTI or acute pyelonephritis. Loss of tubular function
and the ability to concentrate urine give rise to polyuria
and nocturia, and mild proteinuria is common. Severe
hypertension often is a contributing factor in the prog-
ress of the disease. Chronic pyelonephritis is a signifi-
cant cause of chronic kidney disease and renal failure.
Drug-Related Nephropathies
Drug-related nephropathies involve functional or struc-
tural changes in the kidneys that occur after exposure to
a drug.
4,5,23–26
Because of their large blood flow and high
filtration pressure, the kidneys are exposed to any sub-
stance that is in the blood. The kidneys also are active in
the metabolic transformation of drugs and therefore are
exposed to a number of toxic metabolites. Renal tubular
cells, particularly proximal tubule cells, are vulnerable
to the toxic effects of drugs because their role in con-
centrating and reabsorbing glomerular filtrate exposes
them to high levels of circulating toxins. The tolerance
to drugs varies with age and depends on renal function,
RELAXED
MICTURITION
MICTURITION
NORMAL
SHORT INTRAVESICAL URETER
Flap
Bladder
wall
Ureter
A
B
FIGURE 25-11.
Anatomic features of the ureter and bladder
and their relationship to vesicoureteral reflux.
(A)
In the normal
bladder, the distal portion of the intravesical ureter courses
between the mucosa and the muscularis of the bladder. A
mucosal flap is thus formed. On micturition, the elevated
intravesicular pressure compresses the flap against the
bladder wall, thereby occluding the lumen.
(B)
Persons with
a congenitally short intravesical ureter have no mucosal flap
because the entry of the ureter into the bladder approaches
at a right angle.Thus, micturition forces urine into the ureter.
(Adapted from Jennette JC.The kidney. In: Rubin R., Strayer
DS, eds. Rubin’s Pathology: Clinicopathologic Foundations
of Medicine. 6th ed. Philadelphia, PA: Wolters Kluwer Health
| Lippincott Williams &Wilkins; 2012:795. Courtesy of Dmitri
Karetnikov, artist.)
