Water intoxication: a complication of pelvic US in a patient with syndrome of inappropriate antidiuretic hormone secretion

Iatrogenic water intoxication after pelvic ultrasonography imaging

Ultrasound (US) is a simple, easily accessible, and noninvasive method. Thus, it is commonly used. The bladder should be sufficiently filled to acquire pelvic images by US. This report describes water poisoning in 3 patients with no hepatic, cardiac, or renal disease. Both patients had a history of excessive fluid intake.

Hyponatremic encephalopathy after excessive water ingestion prior to pelvic ultrasound: neuroimaging findings

We report two patients with acute hyponatremic encephalopathy which developed after massive water ingestion for pelvic ultrasound and emphasize the findings of magnetic resonance (MR) imaging including diffusion-weighted imaging (DWI). Both subjects had completely recovered within 24 hours following fluid restriction and salt replacement. MR imaging revealed cortical sulcal narrowing, restricted diffusion and sulcal T2 hyperintensity along with diffuse pial enhancement suggesting diffuse cerebral cortical cytotoxic edema and blood-brain barrier breakdown. In addition to the first illustration of multimodality MR imaging features of water-intoxication, these two cases also highlight the need for standardized practice on the quantity of water intake recommended to distend the bladder for pelvic ultrasound, especially in patients at risk for serum inappropriate ADH syndrome-related hyponatremia.

Hyponatraemia and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by psychotropic drugs

The use of psychotropic drugs has been associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in a number of case reports. SIADH is characterised by the sustained release of antidiuretic hormone (ADH) from the posterior pituitary. The patients have a reduced ability to excrete diluted urine, ingested fluid is retained, and the extracellular fluid expands and becomes hypo-osmolar. The cardinal signs are hyponatraemia, serum hypoosmolality and a less than maximally diluted urine. Common symptoms include weakness, lethargy, headache, anorexia and weight gain. These symptoms may be followed by confusion, convulsions, coma and death. The early symptoms are vague and nonspecific, and they may even mimic the symptoms of the psychiatric disorder itself. For antidepressants, the risk of SIADH seems to be highest during the first weeks of treatment. For antipsychotics, the risk seems to be more spread out in time. The causative role of the drug may sometimes be difficult to estimate, as even drug-free psychiatric patients, mostly those with schizophrenia, develop SIADH on the basis of psychogenic polydipsia. Smoking is another factor associated with the development of SIADH, and the risk may also increase with age. The acute treatment of SIADH induced by a psychotropic drug includes discontinuation of the drug as well as restriction of fluid intake. In cases with significant clinical symptoms, infusion of sodium chloride is recommended. After the acute management, it is useful to evaluate the causative role of the drug by performing a water loading test and/or drug rechallenge. If continued treatment with an antidepressant or antipsychotic is indicated, a drug with a different pharmacological profile should be chosen, and the serum sodium levels should be monitored closely. If treatment with the drug that caused SIADH must be continued, concomitant treatment with demeclocycline may reduce the tendency of hyponatraemia.

Case report: hyponatremia associated with nonsteroidal antiinflammatory drugs

The effects of renal prostaglandins on medullary blood flow, active chloride transport, and antidiuretic hormone are important in urine dilution. It is surprising, therefore, that drugs that inhibit prostaglandin synthesis rarely cause hyponatremia. A patient in whom hyponatremia developed during ibuprofen administration is described and other reported cases of this association in adults are reviewed. The previous case reports fall into two well defined groups: first, neonates treated with indomethacin for patent ductus, and second, adults, often elderly, who usually have other diseases that impair urinary dilution. Although hyponatremia is a rare consequence of therapy with prostaglandin inhibitors, certain individuals are at increased risk and should be monitored for this side effect.