Faculty Bibliography

Obesity has been increasingly recognized as a risk factor for kidney disease and both proteinuria and microalbuminuria have been associated with obesity. The actual prevalence of microalbuminuria and proteinuria in obese patients in the United States (US) has not been clearly described in the literature. Furthermore, obesity is associated with risk factors of kidney disease, such as diabetes and hypertension (HTN), and the prevalence of proteinuria and albuminuria excluding these risk factors is uncertain. In this study, we collected urine albumin/creatinine and urine protein/creatinine ratios on obese patients undergoing bariatric surgery to determine the prevalence of albuminuria and proteinuria in obese patients with and without associated diabetes and HTN. The study included 218 obese patients undergoing bariatric surgery at a New York City hospital. The mean age was 42.1 ± 11.3 years. The mean body mass index (BMI) was 43.9 ± 8.1. Diabetes (DM) was present in 25%. HTN was present in 47%. The prevalence of proteinuria and albuminuria was 21% (95% CI: 15.8-27.1%) and 19.7% (95% CI: 14.2-26.2%) respectively. Among those without DM but who had HTN, 22.6% (95% CI: 12.9-35) had proteinuria and 17% (95% CI 8.4-30.9) had albuminuria. Of patients with neither DM nor HTN, 13.3% (95% CI: 7.3-21.6) and 11% (95% CI: 5-17%) had proteinuria and albuminuria, respectively. Diabetics had a significantly higher prevalence of proteinuria and albuminuria than the non-diabetic groups. The non-diabetic groups did not differ significantly from each other in terms of prevalence of proteinuria and albuminuria. The BMI for diabetics did not differ from non-diabetics. On multivariate analysis, only the presence of diabetes was associated with proteinuria and albuminuria. BMI, age, and HTN were not predictive. In conclusion, we found a relatively high prevalence of microalbuminuria and proteinuria in an urban, US, obese population undergoing bariatric surgery. When diabetics were excluded, there was a lower prevalence. Even patients who had neither diabetes nor HTN, still, however, had much greater amounts than seen in the general US population, likely reflecting an adverse effect of obesity itself on renal physiology.

PURPOSE/OBJECTIVE:The use of lung ultrasound (LUS) to identify extravascular lung water has received increasing acceptance. Sonographic B-lines, discrete vertical lines that originate from the pleura, represent pulmonary edema and are correlated with the accumulation of fluid. The goal of this study was to evaluate the utility of LUS to determine the accuracy of prescribed dry weight (DW) in chronic hemodialysis (HD) patients and to ascertain the adequacy of fluid removal. METHODS:LUS was scheduled to be performed pre- and post-HD in 20 patients. The HD prescription and DW challenge were done independent of the results of the LUS. The presence of B-lines was tabulated and compared to the intradialytic ultrafiltration parameters. RESULTS:Of the 20 patients, 3 did not exhibit B-lines at the first dialysis session. In regard to the other 17 patients, B-lines disappeared in 7 patients at the end of the HD session (mean B-lines 4.2-0). One patient was 0.3 kg away from the prescribed dry weight, but the 6 patients were a mean of 1.7 kg below DW. Of the remaining 10 patients, eight decreased but did not eliminate the B-lines (mean B-lines 15.5-3.8) and were a mean of 3.8 kg below DW post-HD. Two patients who exhibited more cardiac insufficiency than initially recognized could not reach DW or eliminate the B-lines. Eight patients who had residual B-lines at the end of the first HD session had their DW re-estimated and had a second session. Two were able to eliminate the B-lines (mean 2.5-0) and reached a mean of 1.2 kg below DW. Six did not eliminate the B-lines (mean 11.5-4.2) but were able to reach a mean of 0.6 kg below DW. Correlation analysis showed a statistically significant correlation (P < 0.05) between the intradialytic percent change in B-lines and the percent change in total body weight (r = 0.40) and ultrafiltration rate (r = 0.33). Seven of 10 patients with clear chest X-rays pre-HD exhibited B-lines. CONCLUSIONS:This study supports the hypothesis that reduction in B-lines during HD can provide accurate information regarding changes in pulmonary fluid content. Further, LUS is a valuable diagnostic tool for recognizing both the adequacy of fluid removal and the occurrence of error in the estimation of dry weight by usual clinical parameters.

PURPOSE/OBJECTIVE:Functional iron deficiency (FID) is a major cause of persistent anemia in dialysis patients and also contributes to a suboptimal response to erythropoietin (Epo) administration. Vitamin C acts as an enzyme cofactor and enhances mobilization of the ferrous form of iron to transferrin thus increasing its bioavailability. High-dose intravenous vitamin C has been shown to decrease the Epo requirement and improve hemoglobin levels in previous studies. This study assessed the effect of low-dose oral vitamin C on possible reduction in Epo dose requirements in stable hemodialysis patients with FID. METHODS:This prospective study included 22 stable hemodialysis patients with FID defined as transferrin saturation (T sat) <30 % and ferritin levels of >100 mcg/L with Epo requirement of ≥4000 U/HD session. Patients received oral vitamin C 250 mg daily for 3 months. Hemoglobin, iron and T sat levels were recorded monthly. No one received iron supplementation during the study period. RESULTS:There was a significant reduction in median Epo dose requirement in the 15 patients who completed the study, from 203.1 U/kg/week (95 % CI 188.4-270.6) to 172.8 U/kg/week (95 % CI 160.2-214.8), (P = 0.01). In the seven responders, there was 33 % reduction in Epo dose from their baseline. Despite adjustment of Epo dose, the mean hemoglobin level was significantly increased from 10.1 ± 0.6 to 10.7 ± 0.6 mg/dL (P = 0.03). No adverse effects of oral vitamin C were observed. CONCLUSION/CONCLUSIONS:Daily low-dose oral vitamin C supplementation reduced Epo dose requirements in hemodialysis patients with FID. Limitations of this study include a small sample size and the lack of measurements of vitamin C and oxalate levels. Despite concerns regarding oral vitamin C absorption in dialysis patients, this study indicates vitamin C was well tolerated by all participants without reported adverse effect.

Steroids are the mainstay of treatment for renal sarcoidosis. Many patients with sarcoidosis are chronically dependent on steroids and there is limited data on the use of steroid-sparing agents. This is a case of a patient that has remained in remission using mycophenolate mofetil (MMF) as a steroid-sparing agent. The patient is a 56-year-old female with a history of sarcoidosis diagnosed by lymph node biopsy who developed 3 episodes of acute kidney injury (AKI) in the setting of exacerbations of her sarcoidosis, each responding to prednisone treatment. Due to possible lifelong need for prednisone, MMF was started as a steroid-sparing treatment. She tolerated the MMF well and has now been steroidfree for 22 months. There have been only a few case reports about the use of MMF as a steroid-sparing agent in sarcoid-associated renal disease, in which patients could be successfully weaned off steroids. This is the longest reported follow-up of a patient being off steroids while on MMF. It is also notable for the patient having a relapse on the MMF which responded to an increased dose. MMF should be studied further as a potential steroid-sparing agent in the treatment of sarcoid associated renal disease.

The pressor and antidiuretic actions of arginine vasopressin (AVP) have been well documented. This review focuses on the less widely appreciated actions of AVP which also have important physiologic functions and when better understood may provide important insights into common disease states. These actions include effects on pain perception and bone structure as well as important relationships to the varied components of metabolic syndrome. These include effects on blood glucose, lipid levels, and blood pressure. AVP may also play a role in the progression of chronic kidney disease and effect physiologic changes relating to aging, abnormal social behavior, and cognitive function. Important cellular responses including cell proliferation, inflammation, and control of infection and their relationship to AVP are described. Finally, the effects of AVP on hemostasis and the hypothalamic-pituitary-adrenal axis are noted. The goal of this summary of the various actions of AVP is to direct attention to the potential benefits of research in these underemphasized areas of importance.

A 69-year-old male had initially presented with low-grade proteinuria, microhematuria, and a positive myeloperoxidase anti-neutrophilic antibody (ANCA). He subsequently developed deterioration of kidney function and developed uremic symptoms. Creatinine was 486.2 mumol/L (5.5 mg/dL). Anti-MPO was positive (titer >8 U, normal <0.4). He was clinically diagnosed with rapidly proliferative glomerulonephritis most likely due to ANCA vasculitis. He received three doses of pulse methylprednisolone therapy. Kidney biopsy showed pauci-immune glomerulonephritis. Immunofluorescence was positive for faint linear IgG staining of glomerular basement membrane (GBM). Anti-GBM antibody was positive 2.1 U (normal <1). He was started on high-dose oral steroids; monthly intravenous cyclophosphamide and plasmapheresis were also initiated. His symptoms improved and creatinine is 247.5 mumol/L (2.8 mg/dL). His repeat anti-GBM antibody was negative. This is a rare case of rapidly progressive glomerulonephritis due to dual MPO-ANCA antibodies and anti-GBM antibodies (DAV).