ABSTRACT
Background:
Gestational diabetes insipidus (DI) is a very rare complication of
pregnancy. We present a case of gestational DI combining two different types of DI. Case Presentation. A 39-year-old
pregnant woman suddenly presented with
thirst,
polydipsia, and
polyuria after 31
gestation weeks (GWs). Based on
laboratory findings of hypotonic
urine (78 mOsm/kgH2O) with higher
plasma osmolality (298 mOsm/kgH2O) and higher
serum sodium levels (149 mEq/L), gestational DI was suspected, and the
clinical course was monitored without
therapy until the results of a measurement of
plasma arginine vasopressin (AVP) levels were available. However, she subsequently developed acute prerenal failure and underwent an
emergency cesarean section at 34 GWs. Her resected
placenta weighed 920 g, nearly twice the normal weight. Immediately following delivery, intranasal 1-desamino-8-D-
arginine vasopressin was administered, and her symptoms promptly disappeared. Afterward, her predelivery
plasma AVP level was found to have been inappropriately low (0.7 pg/mL) given her
serum sodium level. The
patient's
serum vasopressinase level just before delivery was 2,855 ng/mL, more than 1,000 times the upper limit of the
normal range, suggesting excess
vasopressinase-induced DI. The presence of anti-
rabphilin-3A antibodies in the
patient's
blood, a hypertonic saline infusion test result, and loss of the high-intensity signal of the posterior pituitary on fat-suppressed T1-weighted
magnetic resonance images without thickening of the stalk and enlargement of the
neurohypophysis suggested concurrent central DI-like lymphocytic infundibulo-neurohypophysitis (LINH).
Conclusion:
In addition to the degradation of AVP by excess placental
vasopressinase due to the enlarged
placenta, an insufficient compensatory increase in AVP
secretion from the
posterior pituitary gland due to LINH-like pathogenesis might have led to DI symptoms.