Book of Medical Disorders in Pregnancy - Tintash

Chapter No: 6
RENAL DISEASE IN PREGNANCY
Fig6.1: Shows locations of kidneys and
its relations with pancreas
In pregnancy, physiological and
anatomical changes in the urinary tract
occur in response to a variety of factors.
Knowledge of these changes is important
for the understanding and management
of the various disease entities
that occur in the genitourinary system of
the pregnant patient.
Major physiological changes in the
urinary tract in pregnancy - The
increased b100d flow to the kidney
during pregnancy, which approximates
50% above normal, begins early in
pregnancy and by the second month is
well established. As a result of the
increased renal blood flow both in the
erect and supine positions, changes
occur in many of the fundamental
physiological functions of the kidney,
they include. Glomerular filtration rate
88
(GFR) is increased by 50% by the
second month and increases steadily to
term. BUN (b blood urea nitrogen) is
reduced to 8.5 = 1.5 mg, %. The normal
level in the non pregnant state is 1.3 + 3
mg %. serum creatinine is reduced to
0.46 = 0.6 mg%. The normal level in the
non pregnant state is 0.767 1: 0.17 mg
%. clearance studies are not particularly
reliable in pregnancy (i.e. inulin etc.).
However, creatinine clearance parallels
roughly to the glomerular filtration rate,
so it is increased in pregnancy. These
changes in GFR, BUN and serum creatinine
may lead to a false assumption
that the diseased kidney in pregnancy is
functioning satisfactorily, other changes
which are important to the kidney's
function should be noted but are less
important clinically; plasma aldosterone
level is increased; and sodium reabsorption
is increased.
These physiological alterations may be
necessary for the maintenance of fluid
homeostasis and blood pressure. Glucosuria
and lactosuria may occur in the
normal pregnant patient due to failure of
the kidney to increase its resorptive
power".
Anatomical changes in the renal tract:
From early pregnancy and throughout
the puerperium, the renal collecting
system is dilated (physiological hydronephrosis);
peristalsis is decreased.
These changes are clearly established as
early as the second trimester. Dilatation
is usually greater on the right side. The
cause of the dilatation is unknown, but it
is assumed to be largely hormonal, although
mechanical obstruction of the