Early inappropriate secretion of antidiuretic hormone after trans-sphenoidal pituitary adenomectomy

Delayed Hyponatremia after Transsphenoidal Surgery for Pituitary Adenomas: A Single Institutional Experience

Background

Hyponatremia is a common complication after transsphenoidal surgery (TSS) for pituitary adenomas. This study retrospectively reviewed various clinical factors of pituitary adenoma patients who underwent TSS and aimed to identify possible risk factors of postoperative hyponatremia.

Methods

Total 1,343 patients who underwent TSS for their pituitary adenomas in a single institution were enrolled to this study. We identified and analyzed 93 patients (6.9%) with postoperative hyponatremia and compared them with other 1,250 patients in a control group. Patients' age, sex, tumor extent based on the modified Hardy classification, tumor size and hormonal type of the tumors were analyzed in comparison between two groups. The results of pre- and post-operative combined pituitary function test and their comparison were analyzed to elucidate a possible association between postoperative hyponatremia and hypopituitarism.

Results

The onset of postoperative hyponatremia was 7.8 days after surgery (range: postoperative day 3–13). The initial level of serum sodium (Na) level at the start of treatment was 123.5 mmol/L (range: 114–131 mmol/L) and the duration of treatment was 2.7 days (range: 1–9 days). Female predominance was evident in the hyponatremia group (77.4% vs. 61.4%, p=0.02). Preoperative hypopituitarism (58.5% vs. 71.5%, p=0.007) and postoperative hypocortisolism (33.7% vs. 23.4%, p=0.029) were related to postoperative hyponatremia. Other pre- and post-operative clinical factors were not associated with postoperative hyponatremia.

Conclusion

Postoperative hyponatremia is a common complication after TSS and is potentially fatal. Female patients were more likely to develop delayed hyponatremia. We demonstrated possible associations of delayed postoperative hyponatremia with preoperative and postoperative pituitary functions, but the mechanism behind it should be further investigated.

Postoperative Care Following Pituitary Surgery

Patients undergoing surgery for pituitary tumors represent a heterogeneous population each with unique clinical, biochemical, radiologic, pathologic, neurologic, and/or ophthalmologic considerations. The postoperative management of patients following pituitary surgery often occurs in the context of a dynamic state of the hypothalamic-pituitary-end organ axis. Consequently, a significant component of the postoperative care of these patients focuses on vigilant screening and observation for neuroendocrinologic perturbations such as varying degrees of hypopituitarism and disorders of water balance (diabetes insipidus and the syndrome of inappropriate antidiuretic hormone). Additionally, one must be cognizant of other potential complications specific to the transsphenoidal approach for tumor removal including cerebrospinal fluid leakage and meningitis. This review addresses the postoperative management of patients undergoing pituitary surgery with an emphasis on careful screening and recognition of complications.

The Treatment of Cushing's Disease

Cushing's disease (CD), or pituitary-dependent Cushing's syndrome, is a severe endocrine disease caused by a corticotroph pituitary tumor and associated with increased morbidity and mortality. The first-line treatment for CD is pituitary surgery, which is followed by disease remission in around 78% and relapse in around 13% of patients during the 10-year period after surgery, so that nearly one third of patients experience in the long-term a failure of surgery and require an additional second-line treatment. Patients with persistent or recurrent CD require additional treatments, including pituitary radiotherapy, adrenal surgery, and/or medical therapy. Pituitary radiotherapy is effective in controlling cortisol excess in a large percentage of patients, but it is associated with a considerable risk of hypopituitarism. Adrenal surgery is followed by a rapid and definitive control of cortisol excess in nearly all patients, but it induces adrenal insufficiency. Medical therapy has recently acquired a more important role compared to the past, due to the recent employment of novel compounds able to control cortisol secretion or action. Currently, medical therapy is used as a presurgical treatment, particularly for severe disease; or as postsurgical treatment, in cases of failure or incomplete surgical tumor resection; or as bridging therapy before, during, and after radiotherapy while waiting for disease control; or, in selected cases, as primary therapy, mainly when surgery is not an option. The adrenal-directed drug ketoconazole is the most commonly used drug, mainly because of its rapid action, whereas the glucocorticoid receptor antagonist, mifepristone, is highly effective in controlling clinical comorbidities, mainly glucose intolerance, thus being a useful treatment for CD when it is associated with diabetes mellitus. Pituitary-directed drugs have the advantage of acting at the site responsible for CD, the pituitary tumor. Among this group of drugs, the dopamine agonist cabergoline and the somatostatin analog pasireotide result in disease remission in a consistent subgroup of patients with CD. Recently, pasireotide has been approved for the treatment of CD when surgery has failed or when surgery is not an option, and mifepristone has been approved for the treatment of Cushing's syndrome when associated with impairment of glucose metabolism in case of the lack of a surgical indication. Recent experience suggests that the combination of different drugs may be able to control cortisol excess in a great majority of patients with CD.

Prognostic factors for impaired plasma sodium homeostasis after transsphenoidal surgery

OBJECTIVE

Surgical manipulation of the pituitary stalk, neurohypophysis or the hypothalamus may disturb control of the plasma sodium level. The factors that might predict the risk of postoperative sodium imbalance are not clear, and were investigated in this study.

METHODS

A retrospective survey of 129 surgical records for the occurrence of plasma sodium levels outside the normal range, following transsphenoidal procedures. Median patient age was 49 (range 20-78) years, 65 female. 73 of the operated lesions were non-functioning pituitary adenomas. Patients were considered to have impaired plasma sodium balance if the range of 135-145 mmol/L was not maintained.

RESULTS

Of all 129 surgical cases, 68 (53%) experienced an imbalance in sodium levels. Severe sodium imbalance (≥ 149 or ≤ 131 mmol/L) was observed in 28 patients (22%). 13 showed hypernatraemia (median day 1), and 15 hyponatraemia (median day 6). Tumour size was associated with an increased incidence of sodium imbalance, particularly in patients younger than 49 years; surgery resulted in sodium imbalance in 38% of young patients operated on for tumours < 22 mm and in 76% of young patients, operated on for tumours ≥ 22 mm. Overall, tumour size increased with patients' age, and tumour size was less predictive for sodium disturbances in elderly patients. Median time in hospital was 5 days for patients without sodium imbalance, 6 days for patients with hypernatraemia and 11 days for patients with hyponatraemia.

CONCLUSIONS

Following pituitary surgery, patients with large tumours, in particular those of young age, are at higher risk for losing control of their plasma sodium level. Increased ADH secretion (hyponatraemia), but not transient diabetes insipidus was associated with a prolonged hospital stay. Postoperative follow-up of patients with sellar tumours should include careful monitoring of plasma sodium levels within the first two postoperative weeks and clear patients' instructions.

Hyponatremia after transsphenoidal surgery for hypothalamo-pituitary tumors

Transient diabetes insipidus is a well-known complication after transsphenoidal surgery (TSS). On the other hand, transient hyponatremia has been reported as being a delayed complication of TSS. Transient hyponatremia has been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the details of hyponatremia have not been clarified. In the present study, we retrospectively reviewed 110 consecutive patients (39 males and 71 females, age 9-80 years) operated on transsphenoidally for pituitary and hypothalamic tumors. We investigated the frequency, time of onset, duration of hyponatremia after TSS, and analyzed possible factors associated with it. A postoperative sodium concentration <135 mEq/l was observed in 29 (26%) patients. Five patients were excluded from this study because their hyponatremia could be due to either overdose of desmopressin or SIADH for meningitis. Therefore, we investigated 24 (22%) patients with hyponatremia in this study. The sodium levels in the patients with hyponatremia ranged from 110 to 134, with a mean of 126.2 +/- 5.3 mEq/l. Hyponatremia was observed on average on postoperative day 9.5 +/- 2.4, the serum sodium levels normalized within 3.8 +/- 1.7 days. Hyponatremia occurred in patients with non-functioning pituitary adenoma (26%, 11/42), Rathke's cleft cyst (29%, 5/17), prolactinoma (31%, 4/13) and acromegaly (15%, 4/27). 18 patients (75%, 6/24) who developed hyponatremia had macrotumor (>10 mm), and 6 patients (25%, 6/24) had microtumor. The plasma arginine vasopressin (AVP) levels in the patients with hyponatremia ranged from 0.21 to 2.1, with a mean of 0.79 +/- 0.46 pg/ml, and the levels were inversely correlated with plasma osmolality (r = -0.80, p = 0.002). The urine to plasma osmolality ratios were >1. All the patients received appropriate hormonal replacement, including hydrocortisone. These data showed that postoperative hyponatremia after TSS was not rare, and the hyponatremia was mainly associated with SIADH. As the hyponatremia could be a life-threatening complication, all patients should be screened for serum electrolytes after TSS.

Hyponatremia in the neurosurgical patient: diagnosis and management

Hyponatremia is frequently encountered in patients who have undergone neurosurgery for intracranial processes. Making an accurate diagnosis between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) in patients in whom hyponatremia develops is important because treatment differs greatly between the conditions. The SIADH is a volume-expanded condition, whereas CSW is a volume-contracted state that involves renal loss of sodium. Treatment for patients with SIADH is fluid restriction and treatment for patients with CSW is generally salt and water replacement. In this review, the authors discuss the differential diagnosis of hyponatremia, distinguish SIADH from CSW, and highlight the diagnosis and management of hyponatremia, which is commonly encountered in patients who have undergone neurosurgery, specifically those with traumatic brain injury, aneurysmal subarachnoid hemorrhage, recent transsphenoidal surgery for pituitary tumors, and postoperative cranial vault reconstruction for craniosynostosis.

Very delayed hyponatremia after surgery and radiotherapy for a pituitary macroadenoma

Severe hyponatremia (118 mmol/l) with natriuresis, consistent with cerebral salt wasting syndrome (CSWS), occurred 38 days after transsphenoidal surgery in a 59-year-old woman affected by a pituitary non-functioning macroadenoma. From the 35th day after surgery, she showed progressive polyuria, hypotension and hyponatremia associated with natriuresis, decreased plasma and increased urinary osmolality. The clinical examination revealed signs of dehydration and gradual decline in the level of consciousness. The anterior pituitary function was normal due to appropriate replacement of thyroid and adrenal axis. The patient was treated with saline administration until normal natremia and water balance were restored and neurological symptoms had completely disappeared. This case focuses on the unusually prolonged time of development of post-surgery hyponatremia, despite delayed symptomatic hyponatremia being reported to commonly occur 7 days after transsphenoidal surgery. Therefore, we would advise not to limit the periodic follow-up of the hydroelectrolytic balance to the first two weeks after surgery, but to prolong it until after discharge from hospital. In fact, an early diagnosis is of great importance to prevent permanent neurological damage or death. Since CSWS and syndrome of inappropriate secretion of ADH, the two disorders alternatively imputed to generate post-surgical hyponatremia, are characterized by different pathogenic mechanisms and require opposing therapeutic approaches, the occurrence of extracellular volume dilution or of increased sodium renal loss should be carefully investigated. The evidences in favor of CSWS, the possible mechanisms behind the syndrome and diagnosis and management of patients with post-transsphenoidal surgery CSWS are discussed.

Complications in a contemporary series of patients who underwent transsphenoidal surgery for Cushing's disease

OBJECT

Transsphenoidal surgery is the usual treatment of choice for adrenocorticotropic hormone-secreting pituitary adenomas associated with Cushing's disease. In this paper the authors investigate the complications of transsphenoidal surgery in the treatment of a contemporary series of patients with Cushing's disease.

METHODS

Between January 1992 and December 1997, 105 patients with Cushing's disease underwent transsphenoidal surgery at the University of Virginia Health Sciences Center. A retrospective analysis of the complications was conducted, and the mortality rate was found to be 0.9% and permanent morbidity was 1.8%. The overall number of complications was 14 (13.3%), which included seven complications directly related to surgery; one instance of permanent diabetes insipidus; one syndrome of inappropriate secretion of antidiuretic hormone; and five medical complications (four patients developed deep vein thrombosis and one developed pneumonia).

CONCLUSIONS

Transsphenoidal surgery for Cushing's disease has a higher complication rate than that for pituitary adenomas in general. This is primarily related to a greater number of medical complications, most notably deep vein thrombosis, resulting from the generally debilitated state of most patients with Cushing's disease. In view of the high incidence of deep vein thrombosis in these patients, prophylaxis for thromboembolism during the perioperative period is recommended.

Prevalence, predictors and patterns of postoperative polyuria and hyponatraemia in the immediate course after transsphenoidal surgery for pituitary adenomas

OBJECTIVE

Disturbances of osmoregulation, leading to diabetes insipidus and hyponatraemia are well known complications after surgery in the sella region. This study was performed to examine the prevalence and predictors of polyuria and hyponatraemia after a complete and selective removal of pituitary adenomas was attempted via the transnasal-transsphenoidal approach.

DESIGN

1571 patients with pituitary adenomas (238 Cushing's disease, 405 acromegaly, 534 hormonally inactive adenomas, 358 prolactinoma, 23 Nelson's syndrome, and 13 thyrotropinoma) were daily examined within a 10-day postoperative inpatient observation period. Prevalence of patterns of polyuria (> 2500 ml) and oliguria/hyponatraemia (< 132 mmol/l) were surveyed as well as predictors of postoperative morbidity.

RESULTS

487 patients (31%) developed immediate postoperative hypotonic polyuria, 161 patients (10%) showed prolonged polyuria and 37 patients (2.4%) delayed hyponatraemia. A biphasic (polyuria-hyponatraemia) and triphasic (polyuria-hyponatraemia-polyuria) pattern was seen in 53 (3.4%) and 18 (1.1%) patients, respectively. Forty-one patients (2.6%) displayed immediate postoperative (day 1) hyponatraemia. Altogether, 8.4% of patients developed hyponatraemia at some time up to the 10th day postoperative, with symptomatic hyponatraemia in 32 patients (2.1%). Risk analysis showed that patients with Cushing's disease had a fourfold higher risk of polyuria than patients with acromegaly and a 2.8-fold higher risk for postoperative hyponatraemia. Younger age, male sex, and intrasellar expansion were associated with a higher risk of hypotonic polyuria, but this was not considered clinically relevant.

CONCLUSIONS

The analysis illustrates that disturbances in osmoregulation resulting in polyuria and pertubations of serum sodium concentration are of very high prevalence and need observation even after selective transsphenoidal surgery for pituitary adenomas, especially in patients with Cushing's disease.

Pathophysiology of hyponatremia after transsphenoidal pituitary surgery

Hyponatremia after pituitary surgery is presumed to be due to antidiuresis; however, detailed prospective investigations of water balance that would define its pathophysiology and true incidence have not been established. In this prospective study, the authors documented water balance in patients for 10 days after surgery, monitored any sodium dysregulation, further characterized the pathophysiology of hyponatremia, and correlated the degree of intraoperative stalk and posterior pituitary damage with water balance dysfunction. Ninety-two patients who underwent transsphenoidal pituitary surgery were studied. To evaluate posterior pituitary damage, a questionnaire was completed immediately after surgery in 61 patients. To examine the osmotic regulation of vasopressin secretion in normonatremic patients, water loads were administered 7 days after surgery. Patients were categorized on the basis of postoperative plasma sodium patterns. After pituitary surgery, 25% of the patients developed spontaneous isolated hyponatremia (Day 7 +/- 0.4). Twenty percent of the patients developed diabetes insipidus and 46% remained normonatremic. Plasma arginine vasopressin (AVP) was not suppressed in hyponatremic patients during hypoosmolality or in two-thirds of the normonatremic patients after water-load testing. Only one-third of the normonatremic patients excreted the water load and suppressed AVP normally. Hyponatremic patients were more natriuretic, had lower dietary sodium intake, and had similar fluid intake and cortisol and atrial natriuretic peptide (ANP) levels compared with normonatremic patients. Normnonatremia, hyponatremia, and diabetes insipidus were associated with increasing degrees of surgical manipulation of the posterior lobe and pituitary stalk during surgery. The pathophysiology of hyponatremia after transsphenoidal surgery is complex. It is initiated by pituitary damage that produces AVP secretion and dysfunctional osmoregulation in most surgically treated patients. Additional events that act together to promote the clinical expression of hyponatremia include nonatrial natriuretic peptide-related excess natriuresis, inappropriately normal fluid intake and thirst, as well as low dietary sodium intake. Patients should be monitored closely for plasma sodium, plentiful dietary sodium replacement, mild fluid restriction, and attention to symptoms of hyponatremia during the first 2 weeks after transsphenoidal surgery.

Delayed onset of hyponatremia after transsphenoidal surgery for pituitary adenomas

Hyponatremia is rarely reported as a delayed complication of transsphenoidal resection of pituitary adenoma. Usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), hyponatremia causes nonspecific symptoms, often after hospital discharge. To clarify the frequency, presentation, and outcome of this poorly understood complication, we reviewed our database of 2297 patients who underwent transsphenoidal pituitary surgery between February 1971 and June 1993. Of 53 patients (2.3%) treated for symptomatic hyponatremia, 11 were excluded (2 received arginine vasopressin within 24 hours, 1 had untreated hypothyroidism, 4 had untreated adrenal insufficiency, and 4 had incomplete records). The remaining 42 patients (1.8%), 11 men and 31 women aged 21 to 79 years, presented 4 to 13 days (mean, 8 d) postoperatively with nausea and vomiting (20 patients), headache (18 patients), malaise (12 patients), dizziness (4 patients), anorexia (2 patients), and seizures (1 patient). Hyponatremia was unrelated to sex, age, adenoma type, tumor size, or glucocorticoid tapering. Although the clinical picture in our patients is consistent with SIADH, this was not supported by the antidiuretic hormone levels, which were normal or low-normal in the two patients in whom they were measured, suggesting the possibility that low serum sodium may not reflect SIADH. In all patients, hyponatremia resolved within 6 days (mean, 2 d); treatment consisted of salt replacement and mild fluid restriction in 37 patients and fluid restriction only in 4 (treatment unknown in 1). Delayed hyponatremia after transsphenoidal resection of pituitary adenoma is not as rare as previously thought, nor is it necessarily associated with SIADH or with hypoadrenalism during glucocorticoid tapering.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. Report of nine cases

Hyponatremia, usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone, typically occurs in a delayed fashion following transsphenoidal removal of a pituitary adenoma. In a series of 99 consecutive patients who underwent transsphenoidal surgery for pituitary adenoma, nine patients developed delayed hyponatremia, seven of whom were symptomatic. Of these seven patients, four had been discharged from the hospital and required readmission on postoperative Day 7 to 9. In the nine patients who developed hyponatremia, on the average, serum sodium levels began to fall on Day 4 and reached a nadir on Day 7 (mean serum sodium nadir 123 mmol/L). The development of delayed hyponatremia was associated with the presence of a macroadenoma in eight of the nine patients. Seven of the nine patients had serum sodium levels less than 130 mmol/L and required treatment. One patient was treated with fluid restriction alone and six were treated with both fluid restriction and intravenous urea therapy. Twenty-four and 48 hours after urea administration, serum sodium levels rose by an average of 6 and 10 mmol/L, respectively, and at discharge, levels averaged 136 mmol/L. Intravenous administration of urea provides a rapid yet safe means of correcting symptomatic hyponatremia when fluid restriction alone is inadequate. In this article, the authors discuss the pathogenesis of delayed hyponatremia.