Delayed Onset of Hyponatremia after Transsphenoidal Surgery for Pituitary Adenomas:

Prevention of Hyponatremia After Transsphenoidal Surgery: A Systematic Review

Context: Pituitary adenomas are amongst the most common tumors with a low mortality rate compared to other intracranial malignancies. Delayed hyponatremia (DH) is a common finding after transsphenoidal resection (TSS), which is the basis for the management of these tumors. Although DH is one of the leading causes of readmission after TSS, no unified guidelines exist with regard to the prevention of this electrolyte disturbance. Objectives: This study aims to evaluate and compare existing preventive protocols for DH in order to identify and signify their common grounds. Methods: After a search in electronic databases, including PubMed (NCBI), Embase, Scopus, and Google Scholar with the keywords of “pituitary adenoma,” “hyponatremia,” “transsphenoid surgery”, “water electrolyte balance,” “patient readmission", six original articles were included in the study. Results: We found that a protocol that both identifies groups susceptible to DH (males, older individuals, and those with a lower BMI) and consists of fluid restriction, sodium supplementation, and regular serum sodium monitoring could be utilized to prevent DH in patients with pituitary adenomas after TSS. Conclusions: Further studies with a larger sample size must be conducted to compare existing protocols for preventing DH and also investigate post-surgery optimal fluid-restricted diets and corticosteroid therapy in these patients.

Factors predicting postoperative hyponatremia and efficacy of hyponatremia management strategies after more than 1000 pituitary operations

Object

Syndrome of inappropriate antidiuretic hormone secretion–induced hyponatremia is a common morbidity after pituitary surgery that can be profoundly symptomatic and cause costly readmissions. The authors calculated the frequency of postoperative hyponatremia after 1045 consecutive operations and determined the efficacy of interventions correcting hyponatremia.

Methods

The authors performed a retrospective review of 1045 consecutive pituitary surgeries in the first 946 patients treated since forming a dedicated pituitary center 5 years ago. Patients underwent preoperative and daily inpatient sodium checks, with outpatient checks as needed.

Results

Thirty-two patients presented with hyponatremia; 41% of these patients were symptomatic. Postoperative hyponatremia occurred after 165 operations (16%) a mean of 4 days after surgery (range 0–28 days); 19% of operations leading to postoperative hyponatremia were associated with postoperative symptoms (38% involved dizziness and 29% involved nausea/vomiting) and 15% involved readmission for a mean of 5 days (range 1–20 days). In a multivariate analysis including lesion size, age, sex, number of prior pituitary surgeries, surgical approach, pathology, lesion location, and preoperative hypopituitarism, only preoperative hypopituitarism predicted postoperative hyponatremia (p = 0.006). Of patients with preoperative hyponatremia, 59% underwent medical correction preoperatively and 56% had persistent postoperative hyponatremia. The mean correction rates were 0.4 mEq/L/hr (no treatment; n = 112), 0.5 mEq/L/hr (free water restriction; n = 24), 0.7 mEq/L/hr (salt tablets; n = 14), 0.3 mEq/L/hr (3% saline; n = 20), 0.7 mEq/L/hr (intravenous vasopressin receptor antagonist Vaprisol; n = 22), and 1.2 mEq/L/hr (oral vasopressin receptor antagonist tolvaptan; n = 9) (p = 0.002, ANOVA). While some patients received more than 1 treatment, correction rates were only recorded when a treatment was given alone.

Conclusions

After 1045 pituitary operations, postoperative hyponatremia was associated exclusively with preoperative hypopituitarism and was most efficiently managed with oral tolvaptan, with several interventions insignificantly different from no treatment. Promptly identifying hyponatremia in high-risk patients and management with agents like tolvaptan can improve safety and decrease readmission. For readmitted patients with severely symptomatic hyponatremia, the intravenous vasopressin receptor antagonist Vaprisol is another treatment option.

Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors

Object

Transient delayed postoperative hyponatremia (DPH) after transsphenoidal surgery (TSS) is common and can have potentially devastating consequences. However, the true prevalence of transient symptomatic and asymptomatic DPH has not been studied in a large patient cohort with close and accurate follow-up.

Methods

A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130–134 mEq/L), moderate (125–129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics.

Results

Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = −0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality.

Conclusions

Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified.

Incidence, clinical manifestations, and course of water and electrolyte metabolism disturbances following transsphenoidal pituitary adenoma surgery: a prospective observational study

OBJECT

The authors prospectively studied the incidence, spectrum of clinical manifestations, course, and risk factors of water and electrolyte disturbances (WEDs) following transsphenoidal pituitary adenoma surgery.

METHODS

From the preoperative day to the 14th postoperative day, 57 successive patients undergoing transsphenoidal adenomectomy were monitored daily for body weight, balance of fluids, serum electrolytes, plasma osmolality, plasma antidiuretic hormone (ADH) levels, urinary sodium excretion, urinary osmolality, and subjective sensation of thirst. The type of adenoma operated on and the intraoperative manipulation of the neurohypophysis were also recorded.

RESULTS

Fifty-seven patients (mean age 55 years, 61.4% females) harbored 30 clinically hormone-inactive and 27 hormone-secreting pituitary adenomas. Postoperative WED occurred in 75.4% of the patients: in 38.5% as isolated diabetes insipidus (DI); in 21% as isolated hyponatremia; and in 15.7% as combined DI-hyponatremia. The maximum of medians of diuresis (5.750 L) in patients with isolated DI occurred on postoperative Day 2. Nadir of medians of hyponatremia (132 mmol/L) in patients with isolated hyponatremia occurred on postoperative Day 9. In patients with combined DI-hyponatremia, maximum of medians of diuresis (5.775 L) occurred on the 2nd day and nadir of medians of hyponatremia (130 mmol/L) on the 10th postoperative day. Altogether, 8.7% of the patients had to be treated with desmopressin because of DI persisting for >3 months. Of all the patients with hyponatremia, 42.8% were treated by transient fluid-intake restriction due to an IH of <130 mmol/L with or without clinical symptomatology. Transient acute renal failure occurred in one of these patients. Generally, the occurrence of postoperative WEDs was linked to the intraoperative manipulation of the neurohypophysis. Increased thirst correlated significantly with DI (p=0.001 and 0.02, respectively) and decreased thirst with the hyponatremic episode in patients with combined DI-hyponatremia (p=0.003). Decreased urine osmolality correlated significantly with the presence of DI (p=0.023). Electrolyte-free water clearance and urinary Na+ excretion were not correlated with DI and hyponatremia. Antidiuretic hormone was not suppressed during hyponatremia.

CONCLUSIONS

Water and electrolyte disturbances occurred in the majority of patients undergoing transsphenoidal adenomectomy and were usually transient. Diabetes insipidus is more frequent than hyponatremia. Diabetes insipidus usually occurs during the 1st postoperative day and resolves in the majority of cases within 10 days. In few patients, DI may persist and require therapy with ADH analogs. Hyponatremia usually occurs at the end of the 1st postoperative week and resolves in most cases within 5 days. Very few patients will need treatment other than fluid-intake restriction to avoid serious complications. Thus, careful monitoring of the WEDs in patients undergoing transsphenoidal pituitary adenoma surgery is mandatory for the first 10 postoperative days.

Recognition and management of delayed hyponatremia following transsphenoidal pituitary surgery

Object

The goal of this study was to assess the incidence of symptomatic and occult hyponatremia in patients who had undergone transsphenoidal pituitary surgery.

Methods

Patients who underwent transsphenoidal surgery at the University of Southern California University Hospital between 1997 and 2004 had serum sodium levels drawn on an outpatient basis on postoperative Day 7. Patient records were retrospectively reviewed to determine the incidence of, and risk factors for, symptomatic and asymptomatic hyponatremia.

Two hundred forty-one patients had routine serum sodium levels drawn as outpatients on postoperative Day 7. Twenty-three percent of these patients were found to be hyponatremic (Na ≤ 135 mEq/L). The overall incidence rate of symptomatic hyponatremia in the 241 patients was 5%. The majority of hyponatremic patients (80%) remained asymptomatic, whereas 20% became symptomatic. In patients with symptomatic hyponatremia, the mean sodium level at diagnosis was 120.5 mEq/L, compared with 128.4 mEq/L in asymptomatic, hyponatremic patients (p < 0.0001). Female patients were more likely to develop hyponatremia than male patients (33% compared with 22%, p < 0.03). Fifty-two percent of patients who had transient diabetes insipidus (DI) early in their postoperative course subsequently developed hyponatremia, compared with 21% of those who did not have DI (p < 0.001). Patient age, tumor type, and tumor size did not correlate with development of delayed hyponatremia. Outpatients with moderately and severely low sodium levels were 5 and 12.5 times more likely, respectively, to be symptomatic than were patients with mild hyponatremia.

Conclusions

Delayed hyponatremia occurs more frequently than was previously suspected in patients who have undergone transsphenoidal surgery, especially in female patients and those who have previously had transient DI. The majority of hyponatremic patients remain asymptomatic. Obtaining a serum sodium value on an outpatient basis 1 week after pituitary surgery is helpful in recognition, risk stratification, and subsequent intervention, and may prevent potentially serious complications.

Results of transsphenoidal hypophysectomy in 52 dogs with pituitary-dependent hyperadrenocorticism

OBJECTIVE

To evaluate microsurgical transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism (PDH).

STUDY DESIGN

Prospective study to evaluate the results (survival and disease-free interval, remission, recurrence) and complications of microsurgical transsphenoidal hypophysectomy by clinical follow-up, computed tomography (CT), and urinary corticoid-to-creatinine (C/C) ratios in dogs with PDH. The effect of surgical experience was investigated by comparing results of hypophysectomy cases 1 through 26 and 27 through 52.

ANIMALS OR SAMPLE POPULATION

52 dogs with PDH.

RESULTS

Preoperative CT enabled accurate assessment of pituitary size (24 nonenlarged and 28 enlarged) and localization relative to intraoperative anatomic landmarks. Treatment failures included procedure-related mortalities (five dogs) and incomplete hypophysectomies (four dogs). The 1-year estimated survival rate was 84% (95% confidence interval [CI], 71% to 92%). The 2-year estimated survival rate was 80% (95% CI, 65% to 90%). In 43 dogs, the hyperadrenocorticism went into remission. Hyperadrenocorticism recurred in five dogs. The 1-year estimated relapse-free fraction was 92% (95% CI, 76% to 97%). The main complications were transient, mild, postoperative hypernatremia; transient reduction or cessation of tear production (25 eyes in 18 dogs); permanent (five dogs) or prolonged (nine dogs) diabetes insipidus; and secondary hypothyroidism. Normal tear production had resumed in all but one case after a median period of 10 weeks. In the second case series (27 through 52), the hospitalization period was shorter, the number of dry eyes fewer, the survival fraction greater, and the postoperative mortality lower than in the first series. In 15 dogs in which remission was obtained, postoperative CT images suggested the presence of small pituitary remnants; in 1 of these, hyperadrenocorticism recurred. In 46 dogs, the histological diagnosis was pituitary adenoma.

CONCLUSIONS

Microsurgical transsphenoidal hypophysectomy in dogs with PDH is an effective method of treatment in specialized veterinary institutions having access to advanced pituitary imaging techniques. Postoperative CT findings do not correlate well with remission or subsequent recurrence of hyperadrenocorticism.

CLINICAL RELEVANCE

The neurosurgeon performing hypophysectomies must master a learning curve and must be familiar with the most frequent complications of the operation to recognize them as early as possible and to treat them immediately and effectively. Urinary C/C ratios are sensitive indicators for the assessment of remission and recurrence of hyperadrenocorticism.