Q: 28 year old diabetic female is transferred from OB/Gyn floor with mental status change. 48 hours before, patient had a prolonged labor complicated with bouts of hypotension. On arrival to ICU patient is found to be with blood glucose of 55 mg/dL and sodium of 118 mEq/L. Potassium level was in normal range. Your likely diagnosis?

A) Inadequate nutrition
B) Massive IVF resuscitation
C) post labor diuresis
D) Sheehan's syndrome
E) Overdose of insulin


Answer: D

Pregnancy causes physiological enlargement of pituitary gland and is therefore very sensitive to any kind of hypovolemic shock. Various explanations have been provided of sheehan syndrome presenting as hyponatremia including decrease free-water clearance due to hypothyroidism or from glucocorticoid deficiency or  vasopressin secretion due to hypopituitarism  resulting in inappropriate secretion of antidiuretic hormone. Also, lack of cortisol may cause hypoglycemia. To note, potassium level stays normal as adrenal production of aldosterone is independent of the pituitary gland.


References:

1.Boulanger E, Pagniez D, Roueff S, et al. Sheehan syndrome presenting as early post-partum hyponatremia. Nephrol Dial Transplant 1999;14:2714-5. 

2. Putterman C, Almog Y, Caraco Y, Gross DJ, Ben-Chetrit E. Inappropriate secretion of antidiuretic hormone in Sheehan's syndrome: a rare cause of postpartum hyponatremia. Am J Obstet Gynecol 1991;165(5 Pt 1):1330-3.

3. Bunch TJ, Dunn WF, Basu A, Gosman RI (October 2002). "Hyponatremia and hypoglycemia in acute Sheehan's syndrome". Gynecol. Endocrinol. 16 (5): 419–23