Inappropriate secretion of antidiuretic hormone in Sheehan's syndrome: A rare cause of postpartum hyponatremia

A case of acute Sheehan's syndrome and literature review: a rare but life-threatening complication of postpartum hemorrhage

Background

Sheehan’s syndrome occurs because of severe postpartum hemorrhage causing ischemic pituitary necrosis. Sheehan’s syndrome is a well-known condition that is generally diagnosed several years postpartum. However, acute Sheehan’s syndrome is rare, and clinicians have little exposure to it. It can be life-threatening. There have been no reviews of acute Sheehan’s syndrome and no reports of successful pregnancies after acute Sheehan’s syndrome. We present such a case, and to understand this rare condition, we have reviewed and discussed the literature pertaining to it. An electronic search for acute Sheehan’s syndrome in the literature from January 1990 and May 2014 was performed.

Case presentation

A 27-year-old woman had massive postpartum hemorrhage (approximately 5000 mL) at her first delivery due to atonic bleeding. She was transfused and treated with uterine embolization, which successfully stopped the bleeding. The postpartum period was uncomplicated through day 7 following the hemorrhage. However, on day 8, the patient had sudden onset of seizures and subsequently became comatose. Laboratory results revealed hypothyroidism, hypoglycemia, hypoprolactinemia, and adrenal insufficiency. Thus, the patient was diagnosed with acute Sheehan’s syndrome. Following treatment with thyroxine and hydrocortisone, her condition improved, and she was discharged on day 24.

Her next pregnancy was established 2 years after her first delivery. She required induction of ovulation for the next conception. The pregnancy, delivery, and postpartum period were uneventful. An electronic search of the literature yielded 21 cases of acute Sheehan’s syndrome. Presenting signs varied, including adrenal insufficiency (12 cases), diabetes insipidus (4 cases), hypothyroidism (2 cases), and panhypopituitarism (3 cases), with a median time of presentation after delivery for each of those conditions being 7.9, 4, 18, and 9 days, respectively. Serial changes in magnetic resonance imaging were reported in some cases of acute Sheehan’s syndrome.

Conclusion

Clinicians should be aware of the risk of acute Sheehan’s syndrome after a massive postpartum hemorrhage in order to diagnose it accurately and treat it promptly.

Sodium and water disturbances in patients with Sheehan's syndrome

Sheehan's syndrome has been attributed to ischemic damage of the pituitary gland or hypothalamic-pituitary stalk during the peripartum period. Well-described clinical features of Sheehan's syndrome include hypothyroidism, adrenal insufficiency, hypogonadism, growth hormone deficiency, hypoprolactinemia, and different sodium and water disturbances. The occurrence of sodium and water disturbances associated with Sheehan's syndrome depends on the degree of pituitary damage, time of onset since the initial pituitary insult, and concurrent medical conditions that also may play a role in sodium and water balance. We present a patient with Sheehan's syndrome with severe chronic hyponatremia; discuss a potential problem in the patient's management; and review the literature for various sodium and water disturbances, including acute and chronic hyponatremia as well as overt and subclinical central diabetes insipidus. Although Sheehan's syndrome is more prevalent in developing countries, the increasingly large immigrant population within the United States warrants better awareness of this syndrome and its potential complicating sodium and water disturbances. Prompt diagnosis and an understanding of the pathogenic mechanisms of sodium and water disturbances associated with Sheehan's syndrome may avoid potential treatment-related complications.

Demonstration of reserved anterior pituitary function among patients with amenorrhea after postpartum hemorrhage

To demonstrate the residual pituitary function of patients with Sheehan's syndrome years after the obstetric complication, 14 patients with postpartum hemorrhage followed by secondary amenorrhea and agalactia were included in this review. Due to their unfamiliarity with the clinical symptoms, these patients did not receive pretreatment hormonal therapy. The mean age at their last delivery was 29 years (range 21-38 years). The mean duration between postpartum hemorrhage and the subsequent clinical manifestations leading to the endocrine investigation was 18 years (range 1-33 years). Eight patients presented with symptoms of severe hyponatremia (serum sodium less than 125 mmol/l) more than 16 years (mean 23 +/- 10) after the occurrence of postpartum hemorrhage. The electrolyte abnormality was primarily due to adrenal dysfunction. Seven out of 14 patients had normal basal luteinizing hormone (LH) levels and adequate LH responses to gonadotropin releasing hormone stimulation. Administration of thyrotropin releasing hormone provoked thyrotropin release and/or prolactin secretion in four cases. The manifestation of clinical hypopituitarism and the degree of empty sella on computed tomography scanning did not accurately indicate the secreting ability of the pituitary in patients with Sheehan's syndrome. Although all the patients had amenorrhea, the gonadotropic functions of the pituitary still remain in some patients. Various degrees of other pituitary functions can also been demonstrated even several decades after the occurrence of obstetric complications. Our data suggest that the amenorrhea of Sheehan's patients is not simply due to a dysfunction of the pituitary gonadotrophs.

Case series: hyponatremia associated with moderate exercise

Exercise-induced hyponatremia is commonly believed to be associated only with extraordinary physical efforts, or particularly strenuous exercise. Hyponatremia complicating moderate exercise has not been described previously. The authors describe the characteristics of seven patients with life-threatening hyponatremia associated with mild to moderate exercise. All patients suffered from nausea, vomiting, agitation, and confusion, appearing during or after moderate physical activity. Grand mal convulsions occurred in five of the patients. In laboratory results, hyponatremia was as low as 115 mEq/L, with a relatively high sodium concentration in the urine. High serum creatine kinase activity levels were found in most of the patients. All patients were discharged in good condition, without neurologic sequela. The authors conclude that hyponatremia is a possible complication of moderate exercise, and not only of endurance sports, and that exercise-induced hyponatremia can produce severe neurologic manifestations. The mechanism of the hyponatremia is unclear, but may be due to a hemodynamically inappropriate stimulus for antidiuretic hormone secretion.