High prevalence of renal salt wasting induced by haptoglobin-related protein without signal peptide is linked to new syndrome of salt wasting in Alzheimer disease.

The subject of hyponatremia is undergoing significant changes after developing a more pathophysiologic approach that is superior to the ineffective volume approach and can more effectively identify the different causes of hyponatremia. This new approach identified cerebral salt wasting (CSW) in 24 (38%) of 62 hyponatremic patients from the medical wards of the hospital with 21 showing no evidence of cerebral disease to support our proposal to change CSW to renal salt wasting (RSW). RSW had to be differentiated from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) because of diametrically opposite therapeutic goals of water-restricting water-logged patients with SIADH or administering salt water to volume-depleted patients with RSW. Both syndromes present with identical clinical parameters that require a difficult protocol to make such a differentiation possible. We describe rat clearance studies demonstrating natriuretic activity in the plasma of patients with neurosurgical and Alzheimer diseases (AD) and eventually identify the protein as haptoglobin-related protein without signal peptide, which can serve as a biomarker to simplify diagnosis of RSW and delivery of the proper management to improve clinical outcomes. We also discuss the introduction of a new syndrome of RSW in AD and its implications. The high prevalence of RSW and identification of the natriuretic factor have created debates over the existence of RSW with none questioning or addressing the pathophysiologic data that identified patients with RSW. We also discuss the potentially large group of patients with RSW who are normonatremic.

Haptoglobin-Related Protein without Signal Peptide as Biomarker of Renal Salt Wasting in Hyponatremia, Hyponatremia-Related Diseases and as New Syndrome in Alzheimer's Disease.

The application of pathophysiologic tenets has created significant changes in our approach to hyponatremia and hyponatremia-related conditions. This new approach incorporated the determination of fractional excretion (FE) of urate before and after the correction of hyponatremia and the response to isotonic saline infusion to differentiate the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) from renal salt wasting (RSW). FEurate simplified the identification of the different causes of hyponatremia, especially the diagnosis of a reset osmostat and Addison's disease. Differentiating SIADH from RSW has been extremely difficult because both syndromes present with identical clinical parameters, which could be overcome by successfully carrying out the difficult protocol of this new approach. A study of 62 hyponatremic patients from the general medical wards of the hospital identified 17 (27%) to have SIADH, 19 (31%) with reset osmostat, and 24 (38%) with RSW with 21 of these RSW patients presenting without clinical evidence of cerebral disease to warrant changing the nomenclature from cerebral to renal salt wasting. The natriuretic activity found in the plasma of 21 and 18 patients with neurosurgical and Alzheimer's disease, respectively, was later identified as haptoglobin-related protein without signal peptide (HPRWSP). The high prevalence of RSW creates a therapeutic dilemma of deciding whether to water-restrict water-logged patients with SIADH as compared to administering saline to volume-depleted patients with RSW. Future studies will hopefully achieve the following: 1. Abandon the ineffective volume approach; 2. Develop HPRWSP as a biomarker to identify hyponatremic and a projected large number of normonatremic patients at risk of developing RSW, including Alzheimer's disease; 3. Facilitate differentiating SIADH from RSW on the first encounter and improve clinical outcomes.

New Approach to Hyponatremia: High Prevalence of Cerebral/Renal Salt Wasting, Identification of Natriuretic Protein That Causes Salt Wasting.

Our understanding of hyponatremic conditions has undergone major alterations. There is a tendency to treat all patients with hyponatremia because of common subtle symptoms that include unsteady gait that lead to increased falls and bone fractures and can progress to mental confusion, irritability, seizures, coma and even death. We describe a new approach that is superior to the ineffectual volume approach. Determination of fractional excretion (FE) of urate has simplified the diagnosis of a reset osmostat, Addison's disease, edematous causes such as congestive heart failure, cirrhosis and nephrosis, volume depletion from extrarenal salt losses with normal renal tubular function and the difficult task of differentiating the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) from cerebral/renal salt wasting (C/RSW). SIADH and C/RSW have identical clinical and laboratory parameters but have diametrically opposite therapeutic goals of water-restricting water-loaded patients with SIADH or administering salt water to dehydrated patients with C/RSW. In a study of nonedematous patients with hyponatremia, we utilized FEurate and response to isotonic saline infusions to differentiate SIADH from C/RSW. Twenty-four (38%) of 62 hyponatremic patients had C/RSW with 21 having no clinical evidence of cerebral disease to support our important proposal to change cerebral to renal salt wasting (RSW). Seventeen (27%) had SIADH and 19 (31%) had a reset osmostat. One each from hydrochlorothiazide and Addison's disease. We demonstrated natriuretic activity in the plasma of patients with neurosurgical and Alzheimer diseases (AD) in rat clearance studies and have now identified the natriuretic protein to be haptoglobin related protein without signal peptide (HPRWSP). We introduce a new syndrome of RSW in AD that needs further confirmation. Future studies intend to develop HPRWSP as a biomarker to simplify the diagnosis of RSW in hyponatremic and normonatremic patients and explore other clinical applications that can improve clinical outcomes.

Pathophysiologic approach to understanding and successfully treating idiopathic edema: Unappreciated importance of nocturia.

Idiopathic edema (IE), a disorder of females, is characterized by edema and weight gains exceeding 1.4 kg while assuming an upright position followed by nocturia and returning to a non-edematous baseline weight in the morning. There is no successful treatment of IE and the importance of nocturia needs to be emphasized. The major underlying abnormality is an increase in vascular membrane permeability (VMP). We present four cases with differing degrees of IE who were successfully managed by manipulating Starling's forces. While we could not alter the increase in VMP, manipulating oncotic and hydrostatic pressures between both compartments were untenable except to decrease intravascular hydrostatic pressure by sodium restriction. All four cases virtually eliminated daily weight gains and nocturia to improve quality of life considerably, two with the assistance of daily hydrochlorothiazide (HCTZ) and all four by furosemide to accelerate recovery from the weight gain to permit occasional dietary indiscretions to improve quality of life. Two cases with milder forms of IE did not quantify sodium intake as meticulously as cases one and four, who appeared to have greater increases in VMP. IE can be treated successfully by sodium restriction with or without use of HCTZ and furosemide to eliminate the distressing edema, weight gain and nocturia with marked improvement in emotional instability after understanding that the weight gains and nocturia were linked to dietary intake of sodium.

COVID-19 Antibodies and Outcomes among Outpatient Maintenance Hemodialysis Patients.

Background: Patients on maintenance hemodialysis are particularly vulnerable to infection and hospitalization from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Due to immunocompromised patients and the clustering that occurs in outpatient dialysis units, the seroprevalence of COVID-19 antibodies in this population is unknown and has significant implications for public health. Also, little is known about their risk factors for hospitalization. Methods: Three outpatient maintenance hemodialysis units affiliated with a major teaching hospital in the New York area were studied. We determined rates of SARS-CoV-2 positivity via nasopharyngeal, real-time, reverse-transcriptase PCR (RT-PCR); SARS-CoV-2 IgG seropositivity; hospitalization; and mortality. Results: Of 367 patients, 28% had either SARS-CoV-2 seropositivity or PCR positivity. Prevalence across the three respective units was 7%, 32%, and 70%. Those who were either antibody or PCR positive were significantly younger (65 versus 69 years, P=0.05), and had a higher prevalence of Black race (43% versus 30%, P=0.001) and Hispanic ethnicity (32% versus 12%, P<0.001) compared with those who tested negative. Higher positivity rates were also observed among those who took taxis and ambulettes to and from dialysis, compared with those who used personal transportation. Antibodies were detected in all of the patients with a positive PCR result who underwent serologic testing. Of those that were seropositive, 32% were asymptomatic. The hospitalization rate on the basis of either antibody or PCR positivity was 35%, with a hospital mortality rate of 33%. Aside from COPD, no other variables were more prevalent in patients who were hospitalized. Conclusions: We observed significant differences in rates of COVID-19 infection within three outpatient dialysis units, with universal seroconversion. Among patients with ESKD, rates of asymptomatic infection appear to be high, as do hospitalization and mortality rates.

Evolution and evolving resolution of controversy over existence and prevalence of cerebral/renal salt wasting.

PURPOSE OF REVIEW: The topic of hyponatremia is in a state of flux. We review a new approach to diagnosis that is superior to previous methods. It simplifies identifying the causes of hyponatremia, the most important issue being the differentiation of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) from cerebral/renal salt wasting (RSW). We also report on the high prevalence of RSW without cerebral disease in the general wards of the hospital. RECENT FINDINGS: We applied our new approach to hyponatremia by utilizing sound pathophysiologic criteria in 62 hyponatremic patients. Seventeen (27%) had SIADH, 19 (31%) had a reset osmostat, 24 (38%) had RSW with 21 having no evidence of cerebral disease, 1 had Addison's disease, and 1 was because of hydrochlorothiazide. Many had urine sodium concentrations (UNa) less than 30 mmol/l. SUMMARY: RSW is much more common than perceived in the general wards of the hospital. It is important to change the terminology from cerebral to RSW and to differentiate SIADH from RSW. These changes will improve clinical outcomes because of divergent therapeutic goals of water-restricting in SIADH and administering salt and water to a dehydrated patient with RSW. The present review will hopefully spur others to reflect and act on the new findings and different approaches to hyponatremia.

Macrophage lipid accumulation in the presence of immunosuppressive drugs mycophenolate mofetil and cyclosporin A.

OBJECTIVE: Mycophenolate (MPA) and cyclosporin A (CsA) are two immunosuppressive agents currently used for the treatment of autoimmune diseases. However, reports regarding their effects on inflammation and lipid handling are controversial. Here, we compare the effect of these two drugs on the expression of proteins involved in cholesterol handling and lipid accumulation in a macrophage cell system utilizing M0, M1 and M2 human macrophages and in murine bone marrow-derived macrophages (BMDM). METHODS: Differentiated M0, M1 and M2 subsets of THP-1 human macrophages were subjected to various concentrations of either MPA or CsA. Expression of proteins involved in reverse cholesterol transport (ABCA1 and 27-hydroxylase) and scavenger receptors, responsible for uptake of modified lipids (CD36, ScR-A1, CXCL16 and LOX-1), were evaluated by real-time PCR and confirmed with Western blot. DiI-oxidized LDL internalization assay was used to assess foam cell formation. The influence of MPA was also evaluated in BMDM obtained from atherosclerosis-prone transgenic mice, ApoE-/- and ApoE-/-Fas-/-. RESULTS: In M0 macrophages, MPA increased expression of ABCA1 and CXCL16 in a concentration-dependent manner. In M1 THP-1 macrophages, MPA caused a significant increase of 27-hydroxylase mRNA and CD36 and SR-A1 receptor mRNAs. Exposure of M2 macrophages to MPA also stimulated expression of 27-hydroxylase, while downregulating all evaluated scavenger receptors. In contrast, CsA had no impact on cholesterol efflux in M0 and M1 macrophages, but significantly augmented expression of ABCA1 and 27-hydroxylase in M2 macrophages. CsA significantly increased expression of the LOX1 receptor in naïve macrophages, downregulated expression of CD36 and SR-A1 in the M1 subpopulation and upregulated expression of all evaluated scavenger receptors. However, CsA enhanced foam cell transformation in M0 and M2 macrophages, while MPA had no effect on foam cell formation unless used at a high concentration in the M2 subtype. CONCLUSIONS: Our results clearly underline the importance of further evaluation of the effects of these drugs when used in atherosclerosis-prone patients with autoimmune or renal disease.

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.

CKD, arterial calcification, atherosclerosis and bone health: Inter-relationships and controversies.

Mineral bone disease (MBD) is a common complication of chronic kidney disease (CKD) characterized by disruption of normal mineral homeostasis within the body. One or more of the following may occur: hypocalcemia, hyperphosphatemia, secondary hyperparathyroidism (SHPT), decreased vitamin D and vascular calcification (VC). The greater the decrease in renal function, the worse the progression of CKD-MBD. These abnormalities may lead to bone loss, osteoporosis and fractures. CKD-MBD is a major contributor to the high morbidity and mortality among patients with CKD. Another well-known complication of CKD is cardiovascular disease (CVD) caused by increased atherosclerosis and VC. CVD is the leading cause of morbidity and mortality in CKD patients. VC is linked to reduced arterial compliance that may lead to widened pulse pressure and impaired cardiovascular function. VC is a strong predicator of cardiovascular mortality among patients with CKD. Elevated phosphorus levels and increased calcium-phosphorus product promote VC. Controlling mineral disturbances such as hyperphosphatemia and SHPT is still considered among the current strategies for treatment of VC in CKD through restriction of calcium based phosphate binders in hyperphosphatemic patients across all severities of CKD along with dietary phosphate restriction and use of calciminetics. Additionally, Vitamin D insufficiency is common in CKD and dialysis patients. The causes are multifactorial and a serious consequence is SHPT. Vitamin D compounds remain the first-line therapy for prevention and treatment of SHPT in CKD. Vitamin D may also have atheroprotective effects on the arterial wall, but clinical studies do not show clear evidence of reduced cardiovascular mortality with vitamin D administration. This review discusses the issues surrounding CKD-MBD, cardiovascular disease and approaches to treatment.

High Prevalence of Renal Salt Wasting Without Cerebral Disease as Cause of Hyponatremia in General Medical Wards.

BACKGROUND: The approach to hyponatremia is in a state of flux, especially in differentiating syndrome of inappropriate antidiuretic hormone secretion (SIADH) from cerebral-renal salt wasting (RSW) because of diametrically opposite therapeutic goals. Considering RSW can occur without cerebral disease, we determined the prevalence of RSW in the general hospital wards. METHODS: To differentiate SIADH from RSW, we used an algorithm based on fractional excretion (FE) of urate and nonresponse to saline infusions in SIADH as compared to excretion of dilute urines and prompt increase in serum sodium in RSW. RESULTS: Of 62 hyponatremic patients, (A) 17 patients (27%) had SIADH, 11 were nonresponsive to isotonic saline, and 5 normalized a previously high FEurate after correction of hyponatremia; (B) 19 patients (31%) had a reset osmostat based on normal FEurates and spontaneously excreted dilute urines; (C) 24 patients (38%) had RSW, 21 had no clinical evidence of cerebral disease, 19 had saline-induced dilute urines; 2 had undetectable plasma ADH levels when urine was dilute, 10 required 5% dextrose in water to prevent rapid increase in serum sodium, 11 had persistently increased FEurate after correction of hyponatremia and 10 had baseline urinary sodium < 20 mEq/L; (D) 1 patient had Addison disease with a low FEurate and (E) 1 patient (1.6%) had hyponatremia due to hydrochlorothiazide. CONCLUSIONS: Of the 24 patients with RSW, 21 had no cerebral disease, supporting our proposal to change cerebral-renal salt wasting to renal salt wasting. Application of established pathophysiological standards and a new algorithm based on determination of FEurate were superior to the volume approach for determination of urinary sodium when identifying the cause of hyponatremia.

Application of established pathophysiologic processes brings greater clarity to diagnosis and treatment of hyponatremia.

Hyponatremia, serum sodium < 135 mEq/L, is the most common electrolyte abnormality and is in a state of flux. Hyponatremic patients are symptomatic and should be treated but our inability to consistently determine the causes of hyponatremia has hampered the delivery of appropriate therapy. This is especially applicable to differentiating syndrome of inappropriate antidiuresis (SIAD) from cerebral salt wasting (CSW) or more appropriately, renal salt wasting (RSW), because of divergent therapeutic goals, to water-restrict in SIAD and administer salt and water in RSW. Differentiating SIAD from RSW is extremely difficult because of identical clinical parameters that define both syndromes and the mindset that CSW occurs rarely. It is thus insufficient to make the diagnosis of SIAD simply because it meets the defined characteristics. We review the pathophysiology of SIAD and RSW, the evolution of an algorithm that is based on determinations of fractional excretion of urate and distinctive responses to saline infusions to differentiate SIAD from RSW. This algorithm also simplifies the diagnosis of hyponatremic patients due to Addison's disease, reset osmostat and prerenal states. It is a common perception that we cannot accurately assess the volume status of a patient by clinical criteria. Our algorithm eliminates the need to determine the volume status with the realization that too many factors affect plasma renin, aldosterone, atrial/brain natriuretic peptide or urine sodium concentration to be useful. Reports and increasing recognition of RSW occurring in patients without evidence of cerebral disease should thus elicit the need to consider RSW in a broader group of patients and to question any diagnosis of SIAD. Based on the accumulation of supporting data, we make the clinically important proposal to change CSW to RSW, to eliminate reset osmostat as type C SIAD and stress the need for a new definition of SIAD.

Chronic kidney disease-associated pruritus: impact on quality of life and current management challenges.

Chronic kidney disease-associated pruritus (CKD-aP) is a distressing, often overlooked condition in patients with CKD and end-stage renal disease. It affects ~40% of patients with end-stage renal disease and has been associated with poor quality of life, poor sleep, depression, and mortality. Prevalence estimates vary based on the instruments used to diagnose CKD-aP, and standardized diagnostic instruments are sorely needed. Treatment studies have often yielded conflicting results. This is likely related to studies that are limited by small sample size, flawed designs, and nonstandardized diagnostic instruments. Several large well-designed treatment trials have recently been completed and may soon influence CKD-aP management.

Cholesterol Metabolism in CKD.

Patients with chronic kidney disease (CKD) have a substantial risk of developing coronary artery disease. Traditional cardiovascular disease (CVD) risk factors such as hypertension and hyperlipidemia do not adequately explain the high prevalence of CVD in CKD. Both CVD and CKD are inflammatory states and inflammation adversely affects lipid balance. Dyslipidemia in CKD is characterized by elevated triglyceride levels and high-density lipoprotein levels that are both decreased and dysfunctional. This dysfunctional high-density lipoprotein becomes proinflammatory and loses its atheroprotective ability to promote cholesterol efflux from cells, including lipid-overloaded macrophages in the arterial wall. Elevated triglyceride levels result primarily from defective clearance. The weak association between low-density lipoprotein cholesterol level and coronary risk in CKD has led to controversy over the usefulness of statin therapy. This review examines disrupted cholesterol transport in CKD, presenting both clinical and preclinical evidence of the effect of the uremic environment on vascular lipid accumulation. Preventative and treatment strategies are explored.

The effect of ergocalciferol on uremic pruritus severity: a randomized controlled trial.

OBJECTIVE: Hemodialysis (HD) patients have a high prevalence of pruritus. 25-Hydroxy vitamin D deficiency is common in this population and may play a role in its etiology. Because of this, we studied whether vitamin D2 treatment with ergocalciferol is effective for relief of uremic pruritus severity as measured by pruritus severity surveys. DESIGN, SETTING, AND SUBJECTS: In this double-blind, placebo-controlled, randomized trial, the effect of 12 weeks of ergocalciferol administration on uremic pruritus severity was evaluated. INTERVENTION: Fifty HD patients randomly received either ergocalciferol 50,000 international units (IU) or placebo once weekly for 12 weeks. MAIN OUTCOME MEASURE: Pruritus severity surveys were completed every 2 weeks by all patients starting from baseline until 12 weeks and serve as the main outcome variable. RESULTS: Twenty-five study participants were randomized to ergocalciferol therapy and 25 were randomized to placebo. At baseline, the only significant difference between the two groups was time on dialysis and white blood cell count. Both groups experienced a decrease in pruritus scores from the beginning to the end of study (percent change -38.9% in the treatment group vs. -47.5% in the placebo group). By intention to treat, the treatment × time effect was not statistically significant (F = 0.71, df = (1, 282), P = .34), indicating that the pruritus score was not significantly lower in the treatment group than the placebo group throughout the study. CONCLUSION: In conclusion, we did not find ergocalciferol to be effective for the treatment of uremic pruritus.

Prostaglandin D2 synthase: Apoptotic factor in alzheimer plasma, inducer of reactive oxygen species, inflammatory cytokines and dialysis dementia.

BACKGROUND: Apoptosis, reactive oxygen species (ROS) and inflammatory cytokines have all been implicated in the development of Alzheimer's disease (AD). OBJECTIVES: The present study identifies the apoptotic factor that was responsible for the fourfold increase in apoptotic rates that we previously noted when pig proximal tubule, LLC-PK1, cells were exposed to AD plasma as compared to plasma from normal controls and multi-infarct dementia. PATIENTS AND METHODS: The apoptotic factor was isolated from AD urine and identified as lipocalin-type prostaglandin D2 synthase (L-PGDS). L-PGDS was found to be the major apoptotic factor in AD plasma as determined by inhibition of apoptosis approximating control levels by the cyclo-oxygenase (COX) 2 inhibitor, NS398, and the antibody to L-PGDS. Blood levels of L-PGDS, however, were not elevated in AD. We now demonstrate a receptor-mediated uptake of L-PGDS in PC12 neuronal cells that was time, dose and temperature-dependent and was saturable by competition with cold L-PGDS and albumin. Further proof of this endocytosis was provided by an electron microscopic study of gold labeled L-PGDS and immunofluorescence with Alexa-labeled L-PGDS. RESULTS: The recombinant L-PGDS and wild type (WT) L-PGDS increased ROS but only the WTL-PGDS increased IL6 and TNFα, suggesting that differences in glycosylation of L-PGDS in AD was responsible for this discrepancy. CONCLUSIONS: These data collectively suggest that L-PGDS might play an important role in the development of dementia in patients on dialysis and of AD.

Normal fractional urate excretion identifies hyponatremic patients with reset osmostat.

BACKGROUND: Reset osmostat (RO) occurs in 36% of patients with syndrome of inappropriate antidiuretic hormone secretion (SIADH) and is not often considered when evaluating hyponatremic patients. Patients with RO are not usually treated, but recent awareness that symptoms are associated with mild hyponatremia creates a therapeutic dilemma. We encountered patients with hyponatremia, hypouricemia and high urine sodium concentration (UNa), who had normal fractional excretion (FE) of urate and excreted dilute urines that were consistent with RO. We decided to test whether a normal FEurate in nonedematous hyponatremia irrespective of UNa or serum urate would identify patients with RO. METHODS: We determined FEurate in nonedematous hyponatremic patients. A diagnosis of RO was made if urine osmolality (Uosm) was <200 mOsm/kg in a random urine. We performed a modified water-loading test in patients with a normal FEurate whose random Uosm was >200 mOsm/kg. RESULTS: All nonedematous hyponatremic patients with FEurate of 4%-11% had RO, as determined by Uosm <200 mOsm/kg on a random urine collection in 8 patients, or after a modified water-loading test in 6 patients. Plasma antidiuretic hormone (ADH) in 4 patients was undetectable at <1 pg/mL during water-loading. Nine patients had baseline concentrated urine, 12 had UNa >20 mmol/L, 9 were hypouricemic, yet all had a normal FEurate. Comorbidities were similar to those reported in RO. CONCLUSIONS: RO, a benign form of SIADH, occurs commonly. A normal FEurate in a nonedematous hyponatremic patient is highly suggestive of RO. Determining FEurate is superior to serum urate. The therapeutic dilemma for RO must be resolved.

Hypothesis: an erythropoietin honeymoon phase exists.

TREAT was a recently concluded, and well-powered and designed, study of anemia treatment in chronic kidney disease (CKD). Unlike most previous studies of ESA treatment in nondialysis CKD, TREAT was a placebo-controlled trial. The placebo group in TREAT provides a unique long-term view of a conservative approach to anemia management in nondialysis CKD. The course of mean Hgb levels in the placebo group ran counter to expectations, increasing over time. We discuss possible reasons for this, including a new hypothesis that there may be an erythropoietin 'honeymoon phase' similar to that observed in diabetes mellitus. We propose investigation of this phenomenon as it could lead to less expensive and safer approaches to treatment of CKD anemia.

Anemia treatment in chronic kidney disease accompanied by diabetes mellitus or congestive heart failure.

Anemia is common in chronic kidney disease (CKD). The CHOIR study found increased risk of a composite cardiovascular outcome when anemia was treated with epoetin-alfa to a target hemoglobin level of 13.5 as compared with 11.3 g/dl. Whether this increase applies to all patient subgroups equally is unclear. We discuss an analysis by Szczech and colleagues of the effects of the higher hemoglobin target in CKD patients with diabetes mellitus or congestive heart failure.

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

Risk for acute renal failure in patients hospitalized for decompensated congestive heart failure.

INTRODUCTION: Congestive heart failure (CHF) is an important cause of hospital admissions and is associated with an increased risk for development of acute renal failure (ARF). The purpose of this study was to describe the incidence of ARF, to ascertain risk factors for its development, and to determine whether ARF impacts hospital outcomes. METHODS: Review was conducted of 509 hospital medical records of patients hospitalized with a principal diagnosis of CHF during 2004. ARF was defined as an increase in serum creatinine of 0.5 mg/dl compared to the admission value. Multivariable analysis was used to identify independent predictors of ARF. RESULTS: Most patients had reduced renal function at the time of admission with mean serum creatinine of 1.45 +/- 0.72 and calculated creatinine clearance of 43.1 ml/min. ARF developed during the hospitalization in 21% of patients, with a peak increase in serum creatinine of 0.5-3.3 mg/dl. Most cases occurred on hospital days 4-6 (69.5% of cases). ARF was associated with increased risk for in-hospital mortality and increased length of hospital stay. Risk factors for ARF included diabetes, elevated admission serum creatinine and reduced serum sodium and echocardiographic demonstration of diastolic dysfunction. Neither diuretic nor ACEI/ARB treatment was associated with increased risk. CONCLUSION: ARF is a common complication among patients hospitalized for CHF, and is associated with increased risk for adverse outcomes. Certain clinical characteristics present at the time of admission help identify patients at increased risk.