Hyponatremia in pituitary insufficiency

Perioperative management of diabetes insipidus in children

Managing children with diabetes insipidus (DI) in the perioperative period is complicated and frequently associated with electrolyte imbalance compounded by over- or underhydration. In this study the authors developed and prospectively evaluated a multidisciplinary approach to the perioperative management of DI with a comparison to 19 historical control children. Eighteen children either with preoperative DI or undergoing neurosurgical operations associated with a high risk for developing postoperative DI were identified and managed using a standardized protocol. In all patients in whom DI occurred during or after surgery, a continuous intravenous infusion of aqueous vasopressin was initiated and titrated until antidiuresis was established. Intravenous fluids were given as normal saline and restricted to two thirds of the estimated maintenance rate plus amounts necessary to replace blood losses and maintain hemodynamic stability. In all children managed in this fashion, perioperative serum sodium concentrations were generally maintained between 130 and 150 mEq/L, and no adverse consequences of this therapy developed. In the 24-hour period evaluated, the mean change in serum sodium concentrations between the historical controls was 17.6 +/- 9.2 mEq/L versus 8.36 +/- 6.43 mEq/L in those children managed by the protocol. Hyponatremia occurred less frequently in the children managed with this protocol compared with historical controls.

Perioperative management of diabetes insipidus in children [corrected]

Managing children with diabetes insipidus (DI) in the perioperative period is complicated and frequently associated with electrolyte imbalance compounded by over- or underhydration. In this study the authors developed and prospectively evaluated a multidisciplinary approach to the perioperative management of DI with a comparison to 19 historical control children. Eighteen children either with preoperative DI or undergoing neurosurgical operations associated with a high risk for developing postoperative DI were identified and managed using a standardized protocol. In all patients in whom DI occurred during or after surgery, a continuous intravenous infusion of aqueous vasopressin was initiated and titrated until antidiuresis was established. Intravenous fluids were given as normal saline and restricted to two thirds of the estimated maintenance rate plus amounts necessary to replace blood losses and maintain hemodynamic stability. In all children managed in this fashion, perioperative serum sodium concentrations were generally maintained between 130 and 150 mEq/L, and no adverse consequences of this therapy developed. In the 24-hour period evaluated, the mean change in serum sodium concentrations between the historical controls was 17.6 +/- 9.2 mEq/L versus 8.36 +/- 6.43 mEq/L in those children managed by the protocol. Hyponatremia occurred less frequently in the children managed with this protocol compared with historical controls.

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.

Dual facets of hyponatraemia and arginine vasopressin in patients with ACTH deficiency

OBJECTIVE

Hyponatraemia is often observed in patients with ACTH deficiency who are thought not to suffer from volume depletion. Their high plasma AVP levels relative to plasma osmolality are presumed to be maintained by non-osmotic mechanisms. We attempted to assess volume status from changes in selected clinical measurements related to body fluid balance in the course of i.v. fluid supplementation and following glucocorticoid (GC) replacement in ACTH-deficient patients, and to interpret plasma AVP levels in the context of the estimated volume status.

PATIENTS AND DESIGN

This report consists of three parts. First, an ACTH-deficient patient with hyponatraemia and volume depletion who was followed through volume replacement to recovery after GC replacement is described (case report). Secondly, medical records of five ACTH-deficient patients with hypovolaemia and hyponatraemia were surveyed retrospectively to observe changes in serum levels of sodium, uric acid (UA) and haematocrit (Hct) following i.v. fluid supplementation of low sodium content (retrospective study). Thirdly, five ACTH-deficient patients with or without overt dehydration were studied with regard to body weight, blood pressure, serum sodium, total proteins, Hct and blood urea nitrogen before and after GC replacement (prospective study). Plasma AVP levels were measured after i.v. fluid supplementation without GC replacement in the patients of the retrospective study, and before and after GC replacement in the patients of the prospective study.

RESULTS

The first patient became more hyponatraemic after i.v. fluid supplementation and recovered ultimately from hyponatraemia after GC replacement. In five patients studied retrospectively, the serum sodium levels fell progressively following i.v. fluid supplementation, concurrent with reduction in UA levels and Hct, which indicated the dilutional nature of the hyponatraemia. In the patients observed prospectively, the accumulation of fluid and sodium was indicated by a rise in body weight, blood pressure and serum sodium levels and a decline in Hct and total proteins after GC replacement. Plasma AVP levels rose similarly in patients with dilutional hyponatraemia and in patients with borderline hyponatraemia before GC replacement.

CONCLUSION

Patients with untreated ACTH deficiency may have either of two kinds of hyponatraemia--i.e. borderline hyponatraemia associated with subclinical hypovolaemia, or dilutional hyponatraemia. Similarity of plasma AVP levels in two hyponatraemic states suggests their AVP secretion is regulated by non-osmotic, non-volume mechanisms, possibly released from GC suppression at low plasma osmolality.

A case of Sheehan's syndrome with delirium

A 53 year old woman was brought to a psychiatric clinic because of delirium. Upon immediate examination, severe hyponatremia (105 mEq/L) was detected. She was suspected of having internal diseases and referred to our university hospital. When she reached our hospital she was delirious and showed excitement and agitation. Her electroencephalogram showed low voltage theta waves (20 microV) in all leads. She was hospitalized and diagnosed with acute tonsillar abscess and panhypopituitarism based on various endocrine tests. Her past history suggested that Sheehan's syndrome had developed after child-bearing at age 31, resulting in panhypopituitarism. After administration of antibiotics, the fever and tonsillar abscess gradually recovered, and the correction of electrolytes improved the level of consciousness, suggesting that the hyponatremia had been closely related to the clouding of consciousness. As the subsequent administration of cortisol kept the patient's serum sodium levels within the normal range, a decrease in plasma cortisol seemed to be the major cause of the hyponatremia. Psychological symptoms of panhypopituitarism often included abulia, apathy and occasionally coma. However, it is rare for a patient with panhypopituitarism to be misdiagnosed as having a psychiatric disease with delirium. This rare case is presented.

Severe hypotension and coma secondary to unrecognized chronic anterior hypophysitis

We report an endocrine emergency of a 52-year-old woman with chronic anterior-pituitary failure of autoimmune origin who developed hypopituitary crisis with coma and severe hypotension provoked by an intercurrent bronchopneumonia. At admission to the ICU hypopituitarism had not been diagnosed and only Hashimoto's thyroiditis with thyroid replacement therapy could be obtained from the patient's history. Although the patient presented with somatic signs suggestive of hypopituitarism, other causes of coma and hypotension had first to be excluded. In the absence of specific treatment the patient died 18 h later with refractory cardiac arrest. Diagnosis of acute decompensated chronic hypophyseal failure must be considered if hypothermia, refractory hypotension and signs of infection without fever are associated with a short stature and the loss of axillary and public hair. Waiting for laboratory confirmation of the diagnosis must not delay immediate life-saving specific glucocorticoid treatment.

Bilateral carotid aneurysms unmasked by severe hypopituitarism

We describe a patient who initially presented with severe hyponatraemia and grand mal seizures, without any focal neurological symptoms. The final diagnosis was that of giant bilateral carotid aneurysms extending into the sella turcica with anterior hypopituitarism. To the best of our knowledge, this is the first case report of symmetrical carotid aneurysms manifested exclusively by an acute endocrine emergency with none of the concomitant usual focal signs such as headache, failing vision, oculomotor palsy or subarachnoid hemorrhage.

Hyponatremia and inappropriate secretion of vasopressin (antidiuretic hormone) in patients with hypopituitarism

Severe hyponatremia occurs in some patients with untreated hypopituitarism, but it is not known whether such hyponatremia is caused by the hypersecretion of vasopressin (antidiuretic hormone). This report describes severe, symptomatic hyponatremia in five women 59 to 83 years old (serum sodium, 111 to 118 mmol per liter) who presented with hypopituitarism (which had been previously undiagnosed in four). Plasma vasopressin was inappropriately high (1.3 to 25.8 pmol per liter [1.4 to 28 ng per liter]) in relation to plasma osmolality (236 to 260 mOsm per kilogram of body weight). All five patients had normal renal function and no signs of dehydration or volume depletion. The hyponatremia was resolved within a few days after the institution of hydrocortisone therapy, after infusion of normotonic or hypertonic saline had been found to be less effective. When four of the patients were later restudied while receiving maintenance hydrocortisone treatment, the relation between plasma vasopressin and osmolality was normal. We conclude that ACTH deficiency may cause the syndrome of inappropriate secretion of antidiuretic hormone. The beneficial effect of hydrocortisone is probably exerted through the suppression of vasopressin secretion.

Renal hemodynamics and water excretion in Addison's disease

Patients with Addison's disease have impaired ability to excrete free water. The mechanism of this defect is still not clear. These experiments were designed to help clarify the role of altered renal hemodynamics in the genesis of the defect. Six patients with Addison's disease were studied. Enough salt and water was administered to maintain adequate hydration throughout the study but no hormonal replacement was instituted. After a water load, the urine output (V), free water clearance (CH2O), sodium excretion (UNaV), total solute clearance (COsm), inulin clearance (CIn), and para-aminohippurate clearance (CPAH) were measured by standard clearance techniques. In the control studies V and CH2O were abnormally low. The studies were repeated after administration of DOCA, 2.5 mg daily, for a week. This medication decreased UNaV and improved the plasma electrolyte profile but did not cause a significant change in V, CH2O, GFR, or RPF. The same studies were repeated once more after administration of prednisone, 5 mg daily in divided doses, for a week. This drug induced a marked water diuresis while GFR and RPF remained unchanged. It is concluded that hypovolemia and altered renal hemodynamics are not the only mechanisms of the impaired water excretion in Addison's disease. A severe defect remains after normalization of hypovolemia and this is corrected by prednisone but not by DOCA, through mechanisms which do not involve changes in GFR or RPF.

Management of diabetes insipidus in neurosurgical patients

The authors present a brief review of the problem of diabetes insipidus in neurosurgical patients, with particular emphasis on the differential diagnosis of postoperative and posttraumatic polyuria and the management of diabetes insipidus in these periods. A listing of drugs currently used in its treatment is given.

Role of antidiuretic hormone in the abnormal water diuresis of anterior hypopituitarism in man

To evaluate the role of antidiuretic hormone (ADH) in the defect in water excretion which is characteristic of glucocorticoid deficiency, the effects of hydrocortisone and ethanol upon urinary dilution during a sustained water load were studied in patients with anterior hypopituitarism. A spectrum of defects in urinary dilution was found in the seven patients with anterior hypopituitarism, and the subjects were separable into two groups. Four patients were unable to excrete a urine hypotonic to plasma (group I) while three diluted the urine (group II). In two of the group II patients, despite maintenance of hydration, urinary osmolality later rose to hypertonicity. Physiological doses of hydrocortisone improved urinary dilution in all patients. Submaximal doses of oral hydrocortisone, when given to the group I patients, converted their response to hydration to one characteristic of the group II patients, i.e., an initial hypotonic urine followed by a secondary rise to hypertonicity. Ethanol, a known inhibitor of ADH secretion, had no effect in the group I patients. When two of these patients were pretreated with sub-maximal doses of hydrocortisone, however, so that they were able to transiently dilute the urine, ethanol prevented the secondary rise in urine osmolality. Similarly, the administration of ethanol to the untreated group II patients, when the urine was hypotonic, improved diluting ability as characterized by a lowering of urinary osmolality and an increased excretion of solute-free water in all three patients. Hydrocortisone did not improve urinary dilution in three patients with complete hypophyseal diabetes insipidus and one with both anterior and posterior insufficiency receiving constant infusions of vasopressin. These data suggest, therefore, that inappropriately elevated levels of ADH play a major role in the defect in water excretion of anterior hypopituitarism. Glucocorticoids appear to be necessary for a normal neurohypophyseal response to inhibitory stimuli.

"Essential" hypernatremia due to ineffective osmotic and intact volume regulation of vasopressin secretion

A physiological explanation for sustained hyperosmolality was sought in a patient with histiocytosis. During 23 days of observation with only sodium intake regulated at 100 mEq daily, elevation (mean 310 mOsm/kg of water) and fluctuation (range 298-323) of the fasting plasma osmolality were recorded. The presence of endogenous vasopressin was indicated by the patient's ability to concentrate the urine to as high as 710 mOsm/kg of water with a creatinine clearance of 84 cc/min, and by dilution of the urine in response to alcohol. The failure of increasing fluid intake to as high as 6.2 liters daily to lower the plasma osmolality indicated that deficient fluid intake was not solely responsible for the elevated plasma osmolality. Hypertonic saline infusion during water diuresis resulted in the excretion of an increased volume of dilute urine. The water diuresis continued despite a rise in plasma osmolality from 287 to 339. An isotonic saline infusion initiated during hydropenia resulted in a water diuresis which continued despite a rise in the plasma osmolality from 303 to 320. Stable water diuresis induced during recumbency by either oral ingestion of water or intravenous infusion of normal saline was terminated by orthostasis and resumed with the return to the recumbent position. Antecedent alcohol ingestion blocked the antidiuresis of orthostasis. The data are interpreted as indicating impairment of the osmoreceptor mechanism as the primary cause of the hyperosmolar syndrome. They also indicate that vasopressin secretion was regulated primarily by changes in effective blood volume. Chlorpropamide was found to be an effective treatment for the syndrome.

On the role of antidiuretic hormone in the inhibition of acute water diuresis in adrenal insufficiency and the effects of gluco- and mineralocorticoids in reversing the inhibition

In order to determine whether or not antidiuretic hormone (ADH) is essential to the inhibition of an acute water diuresis in adrenal insufficiency, the response to oral water loads was tested in rats with hereditary hypothalamic diabetes insipidus (DI) which lack ADH. It was found that 60 min after water loads of 3 or 5% of body weight urine flow was significantly lower and urine osmolality significantly higher in adrenalectomized DI rats than in the same DI rats before removal of their adrenal glands. The efficacy of gluco- and mineralocorticoids in reversing the inhibition was then determined in the same adrenalectomized DI rats. Prednisolone alone, administered either acutely or chronically, restored the response in urine flow to that seen in the same rats before adrenalectomy, but failed to correct the defect in urinary dilution. Aldosterone when given alone tended to correct the diluting ability but not the response in urine flow. When these two adrenal cortical hormones were given simultaneously, both the urine flow and urine osmolality were nearly identical to what they had been in the same DI rats before adrenalectomy. These studies strongly suggest (a) that ADH is not essential to the inhibition of an acute water diuresis in adrenal insufficiency, although it may abet the inhibition in individuals without diabetes insipidus, which can elaborate ADH; and (b) that both gluco- and mineralocorticoids are required in adrenal insufficiency in order to fully restore the water diuresis as judged by the dual criteria of urine flow and urine osmolality.