Management of hyponatremia: causes, clinical aspects, differential diagnosis and treatment.

INTRODUCTION: Hyponatremia is the most frequent electrolyte disorder in hospitalised patients. Acute and severe hyponatremia may be a life-threatening situation. However, also mild and chronic hyponatremia may negatively affect the health status (i.e. gait disturbances, attention deficits, falls and fractures, and bone loss) and may increase the risk of death. Therefore, it is of paramount importance for clinicians to have an in-depth knowledge on this topic, in order to appropriately manage patients affected by hyponatremia. AREAS COVERED: This review will cover different areas related to this electrolyte disorder. Because many pathologic conditions may be associated with hyponatremia, thorough investigations have to be performed in order to establish the underlying etiology. To establish the cause of hyponatremia is of great importance, because an appropriate therapeutic strategy is strictly dependent on a correct diagnosis. A description of the different available therapeutic approaches for the correction of hyponatremia, including vaptans, will follow. EXPERT COMMENTARY: Undoubtedly, the studies that have been published in recent years and the introduction of vaptans in clinical practice have contributed to increase the awareness on hyponatremia among clinicians. Nevertheless, additional studies are needed in order to clarify some partially uncovered areas.

Recurrent Rathke's Cleft Cysts: Incidence and Surgical Management in a Tertiary Pituitary Center over 2 Decades.

BACKGROUND: Limited data exist pertaining to outcomes following surgery for recurrent Rathke's cleft cysts (RCC). OBJECTIVE: To determine treatment outcomes in patients undergoing reoperation for recurrent or residual RCCs. METHODS: A retrospective analysis of 112 consecutive RCC operations in 109 patients between 1995 and 2017 was conducted. RESULTS: Eighteen patients underwent 21 RCC reoperations with a mean follow-up of 58 mo. Patient symptoms prior to reoperation included headaches (14, 66.7%) and vision loss (12, 57.1%). Thirteen of 18 patients (72.2%) required hormone supplementation prior to reoperation including 5 with diabetes insipidus (DI). Mean RCC diameter was 16 mm and 76% had suprasellar extension. Compared to index RCC cases, intraoperative cerebrospinal fluid leak repair was more common in reoperation cases (15/21, 71% vs 43/91, 47%, P = .05). There was 1 carotid artery injury without neurological sequelae, and 2 postoperative cerebrospinal fluid (CSF) leaks (9.5%). Rates of transient hyponatremia (3/10, 30% vs 4/91, 4.4%, P = .04) and transient DI (5/10, 50% vs 17/91, 18.7%, P = .04) were higher in the reoperation vs index group. Improved headaches and vision were reported in 4/12 (33%) and 8/12 (61.5%) of RCC reoperation patients, respectively. Two patients developed new permanent DI. A higher proportion of reoperation patients had RCC squamous metaplasia (24% vs 5.4%, P = .02) or wall inflammation (42.9% vs 2.2%, P < .001) on pathological examination. CONCLUSION: Reoperation for RCCs is generally safe at tertiary pituitary centers and often results in improved vision. Hypopituitarism is less likely to improve following reoperation for recurrent RCCs. Several histopathological features may help characterize "atypical RCCs" with a higher likelihood of recurrence/progression.

Venlafaxine hyponatraemia: incidence, mechanism and management.

OBJECTIVE: This prospective study was performed on patients aged >65 years commencing therapy with venlafaxine, in order to determine the incidence of hyponatraemia induced by the drug, to investigate the underlying pathophysiological mechanisms, and to evaluate a simple approach to management of this condition. METHOD: All patients aged >65 years seen by one author (MR) from all referral sources were entered into the study. Baseline biochemical tests were ordered, and if hyponatraemia developed (plasma Na <130 mmol L(-1)) additional tests were performed to ascertain the mechanism, while the patient continued on venlafaxine and fluid restriction was instituted. RESULTS: A total of 58 patients were seen, of whom 10 developed hyponatraemia, giving an incidence of 17.2%. Of these 10 patients, five were excluded from prolonged observation because of either severe medical illness, side-effects from the antidepressant or being lost to follow up. When hyponatraemia developed, it invariably did so within a few days of starting venlafaxine, and was associated with non-suppression of antidiuretic hormone in the face of a low serum osmolality. Fluid restriction (800 mL day(-1)) was effective in raising the plasma sodium to the normal range within 2 weeks, after which the fluid restriction could be relaxed without relapse occurring. These patients remained well for the follow-up period of up to 6 months. CONCLUSIONS: Patients >65 years of age should have their electrolytes measured 3-5 days after starting venlafaxine therapy. If hyponatraemia develops, it can be managed with modest fluid restriction without discontinuing drug treatment, subject to close continued clinical observation and biochemical monitoring.