
the antidiuretic mechanism of hydrochlorothia-
zide in the treatment of diabetes insipidus
the changes in water and electro-
lyte balance during hydrochlorothiazide
therapy in 2 patients with vasopressin-
deficient diabetes insipidus were studi-
ed.  in 1 case, under fixed daily so-
dium intake, the urinary sodium excre-
tion markedly increased on the first day
of treatment, but the urinary volume
began to fall on the second day and per-
sisted low for 3 days after discontinua-
tion of the drug.  in the other case the
urinary volume markedly decreased
when the daily sodium intake was strict-
ly limited.  it further decreased on
hydrochlorothiazide therapy but after
sodium intake was restored it returned
to the pretreatment level despite con-
tinued use of the drug.
the antidiuretic action of hydro-
chlorothiazide in the treatment of dia-
betes insipidus is believed to be related
to the sodium depletion state of the body
brought about by increased output or
decreased intake of sodium.  sodium
and water reabsorption in the proximal
convoluted tubules in the kidney in-
creases and the amount of glomerular
filtrate reaching the distal convoluted
tubules decreases.  thus the final
urinary volume falls.
