Refractory hyponatremia

Cerebral salt-wasting syndrome in a patient with status epilepticus: a rare association

Hyponatraemia is one of the most common and serious electrolyte abnormalities in patients with neurological diseases. Assessing the intravascular fluid status, urine sodium, urine and serum osmolality helps to narrow down the differential diagnosis. Differentiation between cerebral salt-wasting syndrome (CSWS), diabetes insipidus and syndrome of inappropriate antidiuretic hormone (SIADH) secretion is absolutely necessary for correct management of hyponatraemia in this group of patients. In this case report, we have presented a 46-year-old gentleman who was admitted to intensive care unit (ICU) with status epilepticus and developed hyponatraemia during course of his ICU stay, diagnosed as CSWS and managed with normal saline and fludrocortisone. His serum sodium gradually improved, consciousness was regained and later shifted to general ward on antiepileptic treatment.

Childhood acute disseminated encephalomyelitis: an Egyptian pilot study

Describing the variable clinical features, laboratory findings, neuroimaging findings, and treatments given to children who presented with ADEM and following them up both clinically and radiologically. 21 patients were recruited: 14 new cases, and 7 old ones presenting over the preceding 5 years (retrospective review of existing data). 11 males and 10 females, with a mean age of 4.4 years ± 2.7 SD, were included. All new patients were subject to full history, examination and a panel of investigations including MRI of the brain. Treatment was given in the form of pulsed methyl prednisolone or intravenous immunoglobulin (IVIG), followed by clinical and radiological follow-up every 3 months as needed. 11 cases occurred in spring, 8 post vaccine, of which 5 were after oral polio vaccine (OPV). MRI was done for all 21 patients and was abnormal in all of them, CT was done in only 10 patients as was normal in 9. Hyponatremia was seen in 11 patients. All patients who received corticosteroids showed prompt improvement. 6 out of 10 patients who received IVIG first failed treatment. Of the 17 treated patients, 10 had no sequelae and 10 had total lesion resolution on MRI at 3 months, versus 1 and 0 patients, respectively, in the untreated group. We found a disproportionately large number of post vaccination cases, especially after OPV. The association of ADEM with hyponatremia needs further study. MRI is central to diagnosis. Outcome is much better with treatment with steroids being far superior to IVIG. Excess use of IVIG should be discouraged.

Clinico-etiological profile of hyponatremia among elderly age group patients in a tertiary care hospital in Sikkim

Background

Hyponatremia is a common condition observed in hospitalized patients. The incidence is much more in the elderly patients owing to impaired ability to maintain water and electrolyte homeostasis. It is important to evaluate and understand the causes and patient characteristics in order to deliver precise management.

Materials and Methods

Study was conducted at a teaching referral hospital in Sikkim and total of 100 elderly patients, diagnosed with hyponatremia, were enrolled in the study. Detailed medical history, clinical and laboratory examination were performed and data including treatment details were collected. Descriptive analysis was performed and results were correlated with patient characteristics.

Results

Mean age of the patients was 73.87 ± 6.54 years with a male to female ratio of 1:0.96. About 81% of patients were symptomatic among which lethargy (50%), drowsiness (40%), and abnormal behavior (39%) were common symptoms. Most patients (51%) had profound hyponatremia and Syndrome of inappropriate antidiuretic hormone secretion (SIADH) (36%) and drugs (26%) were the most common cause of hyponatremia in this study. The common treatment given in this study was 0.9% NaCl (71%). Mortality of patients in this study was 20%.

Conclusion

Clinicians need to be aware of the common occurrence of hyponatremia in the elderly, especially acutely sick elderly. A systematic approach to its diagnosis with the application of simple standardized diagnostic algorithms can significantly improve the assessment and management of hyponatremia as the outcome in profound hyponatremia is governed by etiology, and not by the serum sodium level.

Determining Fractional Urate Excretion Rates in Hyponatremic Conditions and Improved Methods to Distinguish Cerebral/Renal Salt Wasting From the Syndrome of Inappropriate Secretion of Antidiuretic Hormone

Our evaluation of hyponatremic patients is in a state of confusion because the assessment of the volume status of the patient and determinations of urine sodium concentrations (UNa) >30–40 mEq/L have dominated our approach despite documented evidence of many shortcomings. Central to this confusion is our inability to differentiate cerebral/renal salt wasting (C/RSW) from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), syndromes with diametrically opposing therapeutic goals. The recent proposal to treat most or all hyponatremic patients makes differentiation even more important and reports of C/RSW occurring without cerebral disease leads to a clinically important proposal to change cerebral to renal salt wasting (RSW). Differentiating SIADH from RSW is difficult because of identical clinical parameters that characterize both syndromes. Determination of fractional urate excretion (FEurate) is central to a new algorithm, which has proven to be superior to current methods. We utilized this algorithm and differences in physiologic response to isotonic saline infusions between SIADH and RSW to evaluate hyponatremic patients from the general medical wards of the hospital. In 62 hyponatremic patients, 17 (27%) had SIADH, 19 (31%) had reset osmostat (RO), 24 (38%) had RSW, 1 due to HCTZ and 1 Addison's disease. Interestingly, 21 of 24 with RSW had no evidence of cerebral disease and 10 of 24 with RSW had UNa < 20 mEqL. We conclude that 1. RSW is much more common than is perceived, 2.the term cerebral salt wasting should be changed to RSW 3. RO should be eliminated as a subclass of SIADH, 4. SIADH should be redefined 5. The volume approach is ineffective and 6. There are limitations to determining UNa, plasma renin, aldosterone or atrial/brain natriuretic peptides. We also present data on a natriuretic peptide found in sera of patients with RSW and Alzheimer's disease.

Identifying Different Causes of Hyponatremia With Fractional Excretion of Uric Acid

BACKGROUND

There is controversy over the prevalence of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral or renal salt wasting (RSW), 2 syndromes with identical common clinical and laboratory parameters but different therapies. The traditional approach to the hyponatremic patient relies on volume assessment, but there are limitations to this method.

METHODS

We used an algorithm that relies on fractional excretion of urate (FEurate) to evaluate patients with hyponatremia and present 4 illustrative cases.

RESULTS

Overall, 2 patients had increased FEurate [normal: 4-11%], as is seen in SIADH and RSW. A diagnosis of SIADH was made in 1 patient by correcting the hyponatremia with 1.5% saline and observing a characteristic normalization of an elevated FEurate that is characteristic of SIADH as compared to FEurate being persistently increased in RSW. A patient with T-cell lymphoma had symmetrical leg edema due to lymphomatous obstruction of the inferior vena cava, postural hypotension, pleural effusion, ascites, decreased cardiac output and urine sodium level of 10mmol/L. Saline-induced excretion of dilute urines and undetectable plasma antidiuretic hormone were consistent with RSW. Furosemide, given for presumed heart failure, induced a profound diuresis that required large volumes of fluid resuscitation. A normal FEurate identified a reset osmostat in a transplant patient with a slowly developing pneumocystis carinii pneumonia. A volume-depleted hyponatremic patient with Addison׳s disease had a low FEurate of 1.4%.

CONCLUSIONS

These illustrative cases suggest that an approach to hyponatremia using FEurate may be a useful alternative to traditional volume-based approaches.

[A Case of Severe Hyponatremia Caused by Renal Salt Wasting Syndrome in Oropharyngeal Cancer]

Hyponatremia is one of the electrolyte abnormalities frequently encountered in cancer therapy. Cisplatin is a well-known drug which can raise various adverse events, including hyponatremia. A male with advanced oropharyngeal cancer is presented in the present report, who was treated with radiotherapy with concurrent administration of cisplatin and who underwent a total of three episodes of severe hyponatremia in the course of therapy. The first two attacks of hyponatremia following cisplatin administration were accompanied by dehydration and excessive urination, and the patient recovered in one week with rehydration and salt supplementation. Excessive loss of salt in urine confirmed that these events were caused by renal salt wasting syndrome after cisplatin administration. On the other hand, the third attack was due to the syndrome of inappropriate antidiuretic hormone secretion after surgery for a bone fracture. Estimation of the extracellular fluid volume and salt intake/output balance is always believed to be necessary for the diagnosis and proper management of severe hyponatremia after chemotherapy-based treatment with cisplatin.

Paraneoplastic syndromes in olfactory neuroblastoma

Olfactory neuroblastoma (ONB) is a rare malignant neoplasm of sinonasal tract, derived from olfactory epithelium. Unilateral nasal obstruction, epistaxis, sinusitis, and headaches are common symptoms. Olfactory neuroblastoma shows neuroendocrine differentiation and similarly to other neuroendocrine tumors can produce several types of peptic substances and hormones. Excess production of these substances can be responsible for different types of endocrinological paraneoplastic syndromes (PNS). Moreover, besides endocrinological, in ONB may also occur neurological PNS, caused by immune cross-reactivity between tumor and normal host tissues in the nervous system. Paraneoplastic syndromes in ONB include: syndrome of inappropriate ADH secretion (SIADH), ectopic ACTH syndrome (EAS), humoral hypercalcemia of malignancy (HHM), hypertension due to catecholamine secretion by tumor, opsoclonus-myoclonus-ataxia (OMA) and paraneoplastic cerebellar degeneration. Paraneoplastic syndromes in ONB tend to have atypical features, therefore diagnosis may be difficult. In this review, we described initial symptoms, patterns of presentation, treatment and outcome of paraneoplastic syndromes in ONB, reported in the literature.

Differentiating SIADH from Cerebral/Renal Salt Wasting: Failure of the Volume Approach and Need for a New Approach to Hyponatremia

Hyponatremia is the most common electrolyte abnormality. Its diagnostic and therapeutic approaches are in a state of flux. It is evident that hyponatremic patients are symptomatic with a potential for serious consequences at sodium levels that were once considered trivial. The recommendation to treat virtually all hyponatremics exposes the need to resolve the diagnostic and therapeutic dilemma of deciding whether to water restrict a patient with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or administer salt and water to a renal salt waster. In this review, we briefly discuss the pathophysiology of SIADH and renal salt wasting (RSW), and the difficulty in differentiating SIADH from RSW, and review the origin of the perceived rarity of RSW, as well as the value of determining fractional excretion of urate (FEurate) in differentiating both syndromes, the high prevalence of RSW which highlights the inadequacy of the volume approach to hyponatremia, the importance of changing cerebral salt wasting to RSW, and the proposal to eliminate reset osmostat as a subtype of SIADH, and finally propose a new algorithm to replace the outmoded volume approach by highlighting FEurate. This algorithm eliminates the need to assess the volume status with less reliance on determining urine sodium concentration, plasma renin, aldosterone and atrial/brain natriuretic peptide or the BUN to creatinine ratio.

Stress response in critical illness

Sepsis brings about neuroendocrine dysfunction in children that differs significantly from that of adults and can thus be difficult to interpret and manage. Aggressive treatment of sepsis with appropriate and judicious use of antibiotics remains a top priority. Strict glycemic control in children has been associated with significant risk of hypoglycemia, which may independently contribute to morbidity and mortality. Timely initiation of hydrocortisone in persistently hypotensive children with fluid-refractory, catecholamine-resistant shock is controversial, but its use in children with suspected or proven adrenal insufficiency is suggested. Fluid and electrolyte abnormalities must be corrected. Treatment of thyroid dysfunction has been shown to be beneficial in certain specific populations but cannot be extrapolated to all septic patients with the current available data.

Demonstration of natriuretic activity in urine of neurosurgical patients with renal salt wasting

We have utilized the persistent elevation of fractional excretion (FE) of urate, > 10%, to differentiate cerebral/renal salt wasting (RSW) from the syndrome of inappropriate antidiuretic hormone secretion (SIADH), in which a normalization of FEurate occurs after correction of hyponatremia.  Previous studies suggest as well  that an elevated FEurate with normonatremia, without pre-existing hyponatremia, is also consistent with RSW, including studies demonstrating induction of RSW in rats infused with plasma from normonatremic neurosurgical and Alzheimer’s disease patients.  The present studies were designed to test whether precipitates from the urine of normonatremic neurosurgical patients, with either normal or elevated FEurate, and patients with SIADH, display natriuretic activity.  

Methods: Ammonium sulfate precipitates from the urine of 6 RSW and 5 non-RSW Control patients were dialyzed (10 kDa cutoff) to remove the ammonium sulfate, lyophilized, and the reconstituted precipitate was tested for its effect on transcellular transport of ²²Na across LLC-PK1 cells grown to confluency in transwells.

Results: Precipitates from 5 of the 6 patients with elevated FEurate and normonatremia significantly inhibited the in vitro transcellular transport of ²²Na above a concentration of 3 μg protein/ml, by 10-25%, versus to vehicle alone, and by 15-40% at concentrations of 5-20 μg/ml as compared to precipitates from 4 of the 5 non-RSW patients with either normal FEurate and normonatremia (2 patients) or with SIADH (2 patients).

Conclusion: These studies provide further evidence that an elevated FEurate with normonatremia is highly consistent with RSW.  Evidence in the urine of natriuretic activity suggests significant renal excretion of the natriuretic factor. The potentially large source of the natriuretic factor that this could afford, coupled with small analytical sample sizes required by the in-vitro bioassay used here, should facilitate future experimental analysis and allow the natriuretic factor to be investigated as a potential biomarker for RSW.

Common endocrine issues in the pediatric intensive care unit

Thyroid hormone is central to normal development and metabolism. Abnormalities in thyroid function in North America often arise from autoimmune diseases, but they rarely present as critical illness. Severe deficiency or excess of thyroid hormone both represent life-threatening disease, which must be treated expeditiously and thoroughly. Such deficiencies must be considered, because presentation may be nonspecific.

Hyponatremia associated with demyelinating disease of the nervous system

A 63-year-old man was diagnosed with periodontitis and underwent tooth extraction. Several days later, he suffered a high fever, ischuria, a change in personality, and disorientation. A urologist examined him and found severe hyponatremia (117 mEq/L), and he was then transferred to our hospital. On admission, physical findings revealed dysfunction of the bladder and bowel, altered mental status, and hypovolemia. Blood chemistry showed serum sodium of 120 mEq/L, a serum urate of 1.4 mg/dL, urinary Na of 61 mEq/L, and fractional urate excretion of 16 %. Examination of the cerebrospinal fluid (CSF) showed monocytosis. Magnetic resonance imaging (MRI) of the brain and spinal cord showed multiple lesions characterized by hyperintensity on T2-weighted sequences, suggesting demyelinating disease. His sodium concentration normalized 3 days after volume replacement therapy, and his altered mental status along with the dysfunction of the bladder and bowel were promptly improved after the initiation of high-dose glucocorticoids. Additionally, the abnormal lesions on MRI markedly decreased. This clinical course led to the likely diagnosis of acute disseminated encephalomyelitis (ADEM). Hyponatremia in neurologically injured patients is usually attributed to the syndrome of inappropriate antidiuretic hormone (SIADH) or cerebral salt-wasting syndrome (CSWS). In the present patient, the uric acid level remained low and uric acid excretion remained elevated despite correction of the hyponatremia, which suggested CSWS. The differentiation of CSWS from SIADH is difficult but critically important due to the fact that the disorders are managed differently. Coexistence of ADEM and CSWS has rarely been reported.

Syndrome of inappropriate antidiuresis and cerebral salt wasting syndrome: are they different and does it matter?

The syndrome of inappropriate antidiudresis (SIAD) and cerebral salt wasting (CSW) are similar conditions with the main difference being the absence or presence of volume depletion. The two conditions may be indistinguishable at presentation, as volume status is difficult to assess, which can lead to under-diagnosis of CSW in patients with central nervous system (CNS) disease. Carefully conducted studies in patients with CNS disease have indicated that CSW may be more common than SIAD. CSW may be differentiated from SIAD based on the persistence of hypouricemia and increased fractional excretion of urate following the correction of hyponatremia. Hyponatremia should be prevented if possible and treated promptly when discovered in patients with CNS disease as even mild hyponatremia could lead to neurological deterioration. Fluid restriction should not be used for the prevention or treatment of hyponatremia in hospitalized patients with CNS disease as it could lead to volume depletion especially if CSW is present. 0.9% sodium chloride may not be sufficiently hypertonic for the prevention of hyponatremia in hospitalized patients with CNS disease and a more hypertonic fluid may be required. The preferred therapy for the treatment of hyponatremia in patients with CNS disease is 3% sodium chloride.

More on renal salt wasting without cerebral disease: response to saline infusion

BACKGROUND AND OBJECTIVES

The existence and prevalence of cerebral salt wasting (CSW) or the preferred term, renal salt wasting (RSW), and its differentiation from syndrome of inappropriate antidiuretic hormone (SIADH) have been controversial. This controversy stems from overlapping clinical and laboratory findings and an inability to assess the volume status of these patients. The authors report another case of RSW without clinical cerebral disease and contrast it to SIADH.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Three patients with hyponatremia, hypouricemia, increased fractional excretion (FE) of urate, urine sodium >20 mmol/L, and concentrated urines were infused with isotonic saline after collection of baseline data.

RESULTS

One patient with RSW had pneumonia without cerebral disease and showed increased plasma aldosterone and FEphosphate, and two patients with SIADH had increased blood volume, low plasma renin and aldosterone, and normal FEphosphate. The patient with RSW responded to isotonic saline by excretion of dilute urines, prompt correction of hyponatremia, and normal water loading test after volume repletion. Hypouricemia and increased FEurate persisted after correction of hyponatremia. Two patients with SIADH failed to dilute their urines and remained hyponatremic during 48 and 110 h of saline infusion.

CONCLUSIONS

The authors demonstrate appropriate stimulation of ADH in RSW. Differences in plasma renin and aldosterone levels and FEphosphate can differentiate RSW from SIADH, as will persistent hypouricemia and increased FEurate after correction of hyponatremia in RSW. FEphosphate was the only contrasting variable at baseline. The authors suggest an approach to treat the hyponatremic patient meeting criteria for SIADH and RSW and changing CSW to the more appropriate term, RSW

Tumor-related hyponatremia

Hyponatremia is an important and common electrolyte disorder in tumor patients and one that has been reported in association with a number of different primary diagnoses. The correct diagnosis of the pathophysiological basis for each patient is important because it significantly alters the treatment approach. In this article, we review the epidemiology and presentation of patients with hyponatremia, the pathophysiologic groups for the disorder with respect to sodium and water balance and the diagnostic measures for determining the correct pathophysiologic groups. We then present the various treatment options based on the pathophysiologic groups including a mathematical approach to the use of hypertonic saline in management. In cancer patients, hyponatremia is a serious comorbidity that requires particular attention as its treatment varies by pathophysiologic groups, and its consequences can have a deleterious effect on the patient's health.