Massive vasopressin-resistant polyuria induced by dexamethasone

Glucocorticoid-induced acute diuresis in rats in relation to the reduced renal expression of sodium-dependent cotransporter genes

Although several studies have shown that glucocorticoids exert diuretic effects in animals and humans, the underlying mechanism responsible for the acute diuretic effect remains obscure. Here we examined the mechanism in terms of gene-expression. We observed that glucocorticoids, including dexamethasone (Dex) and prednisolone (PSL), acutely induced diuresis in rats in a dose-dependent manner. Free water clearance values were negative after Dex or PSL treatment, similar to those observed after treatment with osmotic diuretics (furosemide and acetazolamide). Dex significantly increased the urinary excretion of sodium, potassium, chloride, glucose, and inorganic phosphorus. Renal microarray analysis revealed that Dex significantly altered the renal expression of genes related to transmembrane transport activity. The mRNA levels of sodium/phosphate (NaPi-2a/Slc34a1, NaPi-2b/Slc34a2, and NaPi-2c/Slc34a3) and sodium/glucose cotransporters (Sglt2/Slc5a2) were significantly reduced in the Dex-treated kidney, being negatively correlated with the urinary excretion of their corresponding solutes. Dex did not affect renal expression of the natriuretic peptide receptor 1 (Npr1) gene, or the expression, localization, and phosphorylation of aquaporin-2 (AQP2), a water channel protein. These findings suggest that the acute diuretic effects of glucocorticoids might be mediated by reduced expression of sodium-dependent cotransporter genes.

A case of neonatal diabetes insipidus following dexamethasone for bronchopulmonary dysplasia

BACKGROUND

Diabetes insipidus (DI) is a disease resulting from defects in the arginine vasopressin system responsible for regulating body water homeostasis. It is characterized by polyuria with increased serum osmolality and sodium and can result from congenital or acquired disorders.

CLINICAL PRESENTATION

A baby was admitted to NICU for extreme prematurity (25 weeks gestation), extreme low birth weight (900 grams) and respiratory distress. He received one dose of Surfactant and was ventilated using high frequency jet ventilation for development of pulmonary interstitial emphysema. After nine days, he still required high settings with development of early chronic lung changes in the form of atelectasis. Therefore, he was started on a course of dexamethasone following the DART study protocol (Dexamethasone: A Randomized Trial). However, after six days (cumulative dose of 0.75 mg/kg/day) he developed polyuria (7.4 ml/kg/h) with increased serum sodium (150 mmol/L) and osmolality (348 mmol/L). He lost 85 grams of his weight in 24 hours, which represented a 9.8 %weight loss. The findings were suggestive of DI and given there were no apparent causes other than dexamethasone, it was discontinued. Over the following 48 hours, polyuria and hypernatremia gradually resolved, reaching 3.5 ml/kg/h, and 140 mmol/L respectively.

CONCLUSION

The use of dexamethasone is not an uncommon practice in tertiary care neonatal units. To our knowledge, our case is the first report of neonatal DI secondary to the use of dexamethasone. We recommend closely monitoring urine output and serum electrolytes in preterm infants receiving dexamethasone.

Central diabetes insipidus unveiled by glucocorticoid therapy in a patient with an empty sella: A case report and literature review

RATIONALE

Some diseases contribute to hypopituitarism without clinical manifestations and the glucocorticoid therapy may unveil central diabetes insipidus. The condition is rare and usually causes problems for clinical physicians.

PATIENT CONCERNS

A 59-year-old woman presented to our hospital due to facial numbness and persistent eyelid heaviness.

DIAGNOSIS

Physical examination and cerebrospinal fluid examination supported a diagnosis of Guillain-Barre[Combining Acute Accent] syndrome. Magnetic resonance imaging showed an empty sella. Hormone test indicated hypopituitarism.

INTERVENTIONS

The patient received intravenous immunoglobulin and glucocorticoid. Central diabetes insipidus appeared after 20 days. Subsequently, the patient was prescribed 1-desamino-8-D-arginine vasopressin and prednisone.

OUTCOMES

During 6 months' follow-up, the patient's urine output was gradually reduced to normal level.

LESSONS

This case indicated that hypopituitarism may be caused by an empty sella and be masked by adrenal insufficiency. Central diabetes insipidus may present after glucocorticoid therapy.

State of affairs in use of steroids in diffuse intrinsic pontine glioma: an international survey and a review of the literature

Children diagnosed with diffuse intrinsic pontine glioma (DIPG) face a dismal prognosis, with severe neurologic deterioration and inevitable death at a median of 9 months from diagnosis. Steroids are widely prescribed as supportive or palliative treatment although they are known to cause severe side effects that may reduce the quality of life. This study aims to review the current knowledge on, and use of, steroids in DIPG patients. A global questionnaire-study among health care professionals was performed to ascertain information on the current (multi-)institutional and (multi-)national use of steroids, the availability of clinical guidelines, and the need for improvements in prescribing steroids to DIPG patients. In addition, an extensive literature search was performed to review studies investigating steroids in pediatric brain tumor patients. From 150 responding health care professionals, only 7 % had clinical guidelines. The use of steroids was heterogeneous and over 85 % of respondents reported serious side effects. Fourteen articles, with low level of evidence, described the use of steroids in pediatric brain tumor patients. Clinical trials investigating optimal dose or regimen were lacking. This study is a first inventory of the availability of evidence-based information and clinical guidelines, and the current attitude towards the use of steroids in DIPG patients. To date, the risk–benefit ratio of steroids in this disease is yet to be determined. We emphasize the need for clinical trials resulting in guidelines on steroids, and possibly alternative drugs, to optimize the quality of care and quality of life of DIPG patients.

Dexamethasone increases aquaporin-2 protein expression in ex vivo inner medullary collecting duct suspensions

Aquaporin-2 (AQP2) is the vasopressin-regulated water channel that controls renal water reabsorption and plays an important role in the maintenance of body water homeostasis. Excessive glucocorticoid as often seen in Cushing's syndrome causes water retention. However, whether and how glucocorticoid regulates AQP2 remains unclear. In this study, we examined the direct effect of dexamethasone on AQP2 protein expression and activity. Dexamethasone increased AQP2 protein abundance in rat inner medullary collecting duct (IMCD) suspensions. This was confirmed in HEK293 cells transfected with AQP2 cDNA. Cell surface protein biotinylation showed an increase of dexamethasone-induced cell membrane AQP2 expression and this effect was blocked by glucocorticoid receptor antagonist RU486. Functionally, dexamethasone treatment of oocytes injected with an AQP2 cRNA increased water transport activity as judged by cell rupture time in a hypo-osmotic solution (66 ± 13 s in dexamethasone vs. 101 ± 11 s in control, n = 15). We further found that dexamethasone treatment reduced AQP2 protein degradation, which could result in an increase of AQP2 protein. Interestingly, dexamethasone promoted cell membrane AQP2 moving to less buoyant lipid raft submicrodomains. Taken together, our data demonstrate that dexamethasone promotes AQP2 protein expression and increases water permeability mainly via inhibition of AQP2 protein degradation. The increase in AQP2 activity promotes water reabsorption, which may contribute to glucocorticoid-induced water retention and hypertension.

Causes of reversible nephrogenic diabetes insipidus: A systematic review

BACKGROUND

In nephrogenic diabetes insipidus (NDI), the kidney is unable to produce concentrated urine because of the insensitivity of the distal nephron to antidiuretic hormone (arginine vasopressin). In settings in which fluid intake cannot be maintained, this may result in severe dehydration and electrolyte imbalances. The risk for conversion of reversible to irreversible NDI seems to be a potential complication. This review summarizes the reversible causes of acquired NDI to facilitate earlier recognition and more effective treatment by clinicians.

METHODS

Two reviewers independently searched MEDLINE, Experta Medica (EMBASE), and ISI bibliographic databases. Human studies that described NDI caused by drugs, substances, or metabolic disturbances were included. To evaluate the causal role of the risk factor, data were abstracted according to Koch's postulates.

RESULTS

One hundred fifty-five studies published between 1957 and March 2004 described 30 risk factors. Of 155 studies, 58 studies provided a "definite" diagnosis of NDI; 83 studies, a "probable" diagnosis; and 14 studies, a "possible" diagnosis. Nine factors were considered "definite" causes of NDI; 15 factors, "probable" causes; and 6 factors, "possible" causes. The most reported risk factors were lithium (84 studies), antibiotics (16 studies), antifungals (11 studies), antineoplastic agents (9 studies), antivirals (8 studies), and metabolic disturbances (8 studies). Duration of NDI reversal, as well as conversion to irreversible symptoms, seemed to depend on the duration of exposure.

CONCLUSION

Most risk factors for reversible NDI were medications, and their identification and removal resulted in resolution of the condition. Long-term treatment with lithium seemed to result in irreversible NDI.

Excruciating perineal pain after intravenous dexamethasone

We describe two cases of unexpected perineal pain immediately after intravenous injection of fentanyl and dexamethasone (100 microg and 8 mg respectively) during induction of general anaesthesia. In both cases the pain was immediate (onset within 30 seconds), severe, localized to the genital region and of shooting and burning character No other clinical signs or symptoms were observed in either case and both patients made an uneventful recovery without neurological sequelae. We review the existing literature on perineal pain as an adverse effect of intravenous corticosteroid esters and recommend their administration either in diluted form or after induction of general anaesthesia.