Kidney Mentoring and Assessment Program for Students: a guide for engaging medical students in nephrology.

BACKGROUND: The American Society of Nephrology's (ASN) Workforce Committee created a unique program called the Kidney Mentoring and Awareness Program for Students to engage medical students in the fight against kidney diseases and interest them in careers in nephrology. METHODS: The program provided a framework and 2 years of funding to three medical schools to organize and carry out health screenings in underserved areas of their communities as well as a structure for student mentoring by the practicing nephrologists. RESULTS: The Workforce Committee identified three medical schools (Emory University, Atlanta, GA; Indiana University, Indianapolis, IN and University of Louisville, Louisville, KY) and engaged faculty at each school to serve as advisors. The ASN committed funding to the groups for 2 years, after which the groups became self-sufficient. Three nephrologists participated in each chapter, building on existing relationships with community groups to identify sites and carry out kidney screening events. CONCLUSIONS: We report here the experience of those chapters and a blueprint for other schools interested in setting up a similarly structured program to interest students in nephrology while working with community groups to spread awareness of the major underlying causes of kidney disease.

Role of oxidative stress in diabetic nephropathy.

Accumulating research suggests that oxidative stress is a significant contributor to the pathogenesis of diabetic nephropathy. The normal kidney generates a substantial amount of oxidative stress because of its high metabolic activity that is balanced by an extensive antioxidant system. However, in pathologic states such as hyperglycemia, nitroso-oxidant balance shifts toward a pro-oxidant state that accelerates tissue and vascular injury. This oxidative damage progresses concomitant with worsening glucose metabolism, vascular dysfunction, and kidney disease. Accordingly, strategies to reduce oxidative stress in diabetes mellitus may exert favorable effects on the progression of diabetic nephropathy.

The interaction between St John's wort and an oral contraceptive.

OBJECTIVES: The popular herbal remedy St John's wort is an inducer of cytochrome P450 (CYP) 3A enzymes and may reduce the efficacy of oral contraceptives. Therefore we evaluated the effect of St John's wort on the disposition and efficacy of Ortho-Novum 1/35 (Ortho-McNeil Pharmaceutical, Inc, Raritan, NJ), a popular combination oral contraceptive pill containing ethinyl estradiol (INN, ethinylestradiol) and norethindrone (INN, norethisterone). METHODS: Twelve healthy premenopausal women who were using oral contraception (>3 months) received a combination oral contraceptive pill (Ortho-Novum 1/35) for 3 consecutive 28-day menstrual cycles. During the second and third cycles, the participants received 300 mg St John's wort 3 times a day. The serum concentrations of ethinyl estradiol (day 7), norethindrone (day 7), follicle-stimulating hormone (days 12-16), luteinizing hormone (days 12-16), progesterone (day 21), and intravenous and oral midazolam (days 22 and 23) were determined in serial blood samples. The incidence of breakthrough bleeding was quantified during the first and third cycles. RESULTS: Concomitant use of St John's wort was associated with a significant (P <.05) increase in the oral clearance of norethindrone (8.2 +/- 2.7 L/h to 9.5 +/- 3.4 L/h, P =.042) and a significant reduction in the half-life of ethinyl estradiol (23.4 +/- 19.5 hours to 12.2 +/- 7.1 hours, P =.023). The oral clearance of midazolam was significantly increased (109.2 +/- 47.9 L/h to 166.7 +/- 81.3 L/h, P =.007) during St John's wort administration, but the systemic clearance of midazolam was unchanged (37.7 +/- 11.3 L/h to 39.0 +/- 10.3 L/h, P =.567). Serum concentrations of follicle-stimulating hormone, luteinizing hormone, and progesterone were not significantly affected by St John's wort dosing (P >.05). Breakthrough bleeding occurred in 2 of 12 women in the control phase compared with 7 of 12 women in the St John's wort phase. The oral clearance of midazolam after St John's wort dosing was greater in women who had breakthrough bleeding (215.9 +/- 66.5 L/h) than in those who did not (97.5 +/- 37.2 L/h) (P =.005). CONCLUSION: St John's wort causes an induction of ethinyl estradiol-norethindrone metabolism consistent with increased CYP3A activity. Women taking oral contraceptive pills should be counseled to expect breakthrough bleeding and should consider adding a barrier method of contraception when consuming St Johns wort.

Ethylene glycol intoxication: case report and pharmacokinetic perspectives.

A 42-year-old man was brought to the emergency department with ethylene glycol intoxication. He was hemodynamically stable and had normal renal function. His serum ethylene glycol concentration was 284 mg/dl approximately 1 hour after ethylene glycol consumption. The patient was treated with fomepizole and forced diuresis. Elimination of ethylene glycol in this patient followed first-order pharmacokinetics. Elimination pharmacokinetics in this patient were compared with that in a patient who received fomepizole and hemodialysis. Fomepizole monotherapy can be given in patients without renal failure or metabolic acidosis even with serum ethylene glycol concentrations greater than 50 mg/dl. However, cost estimates based on this case suggest that if the patient is treated adequately with a single hemodialysis session and 24-hour hospitalization, then fomepizole monotherapy may be more expensive than the combination regimen of fomepizole and hemodialysis.

Evaluation of kidney function in patients with acute renal failure using high-performance liquid chromatography: a case report.

Accurate measurement of glomerular function rate (GFR) in the setting of acute renal failure is difficult to achieve with current clinical methods, such as measuring plasma creatinine concentration and 24-hour urine creatinine clearance. High-performance liquid chromatography was used to measure GFR directly in a critically ill patient with acute renal failure. This approach involved evaluating the elimination kinetics of nonionic contrast material administered intravenously for radiologic imaging. It required no additional patient exposure to radiographic contrast media and enabled caregivers to determine kidney function accurately in the presence of worsening clinical status and delayed changes in plasma creatinine. This and other methods for more accurate measurement of GFR in patients with acute renal failure may provide the foundation for clinical studies that assess the severity and management of acute renal failure.

Liquid chromatography for iothalamate in biological samples.

We have previously reported an iothalamate assay for the assessment of the glomerular filtration rate (GFR) that required a long column equilibration time and 22 min run time per sample. We now report a simpler assay that requires a run time of only 5.5 min and is more precise and accurate than the earlier technique. The mobile phase consisted of methanol-acetonitrile-50 mM sodium monobasic phosphate (10:5:85, v/v) at pH 4.4, pumped at a rate of 1.5 ml/min on a C(18) reversed-phase column. Samples of plasma and urine were deproteinized with 1 volume of 4% perchloric acid or 9 volumes of 2% perchloric acid, respectively. No internal standard was used. The diode array detection system collected absorbance at 240 nm and the peak height areas of iothalamate were determined. The iothalamate peak appeared at 3.5 min. Detector response was linear over the range tested (10-2000 microg/ml). Within-run precision was <3% for both plasma and urine and accuracy was 96-102%. Between-day precision for plasma and urine analyses were <7%. The recovery of iothalamate in urine and plasma were 102% and 91%, respectively. There was excellent thermal and pH stability of iothalamate. No interference was found with para-amino hippuric acid (PAH) or N-acetyl PAH, which can be simultaneously assayed, if desired.

Cocaine-induced acute interstitial nephritis: A case report and review of the literature.

BACKGROUND: Acute tubular necrosis and pigment induced kidney injury are well described consequences of cocaine abuse. However, acute interstitial nephritis associated with cocaine use has been previously reported in only three patients. CASE PRESENTATION: We present the case of a 49-year-old man who developed acute kidney injury from biopsy-proven interstitial nephritis after nasal insufflation of cocaine. Unlike prior reports, our patient remained non-oliguric and did not require renal replacement therapy. CONCLUSIONS: Interstitial nephritis should be considered as a potential cause of acute kidney injury associated with cocaine use. The approach to management of cocaine associated acute kidney injury (AKI) may be different in patients with interstitial nephritis than for those with tubular necrosis or pigment induced renal injury.

Combination therapy of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in chronic kidney disease.

Dual blockade of the renin-angiotensin system (RAS) with a combination of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for the treatment of hypertension and proteinuria has been tested in several randomized trials among patients with chronic kidney disease (CKD). Although combination therapy reduces proteinuria and blood pressure, adequately powered studies evaluating time to end-stage renal disease, death, or cardiovascular outcomes in patients with CKD have not been done. Dual blockade of RAS can cause hyperkalemia, renal failure, and orthostatic hypotension and potentially worsen outcomes; therefore, the risk-benefit ratio in patients with CKD remains unclear. A recent randomized trial in patients with cardiovascular disease or high-risk diabetes raises concerns about the safety of this combination therapy.

A pilot randomized controlled trial of renal protection with pioglitazone in diabetic nephropathy.

BACKGROUND: Diabetic nephropathy progresses relentlessly to end-stage renal disease (ESRD). Animal experiments have found that peroxisome proliferator activated receptor-gamma (PPAR-gamma)-based therapy can have a glucose independent effect on renal protection. We hypothesized that PPAR-gamma-based antidiabetic therapy would result in greater reduction in proteinuria compared to sulfonylurea-based therapy. METHODS: In 44 patients with overt diabetic nephropathy, an open-label, blinded end point trial was conducted in which subjects were randomized to either pioglitazone or glipizide to achieve similar glucose control. Proteinuria was assessed by two collections of 24-hour urine samples each month for 4 months. RESULTS: The glipizide group had an adjusted mean increase in proteinuria of 6.1% (95% CI -11.7%, 23.8%), whereas the pioglitazone group had a reduction of 7.2% (95% CI -24.9%, 10.6%). The adjusted reduction with pioglitazone of 13.2% (95% CI -38.4%, 11.9%) was not statistically significant (P= 0.294). Baseline proteinuria, diastolic ambulatory blood pressure, and serum albumin concentration were independent predictors of reduction in proteinuria. The frequency and patterns of adverse events were similar in the two groups. CONCLUSION: In patients with advanced diabetic nephropathy, we found no reduction in proteinuria over 4 months. These data are useful to design larger studies with longer duration of follow-up to demonstrate renal protection of PPAR-gamma agonists.

Role of excess volume in the pathophysiology of hypertension in chronic kidney disease.

BACKGROUND: The pathophysiology of hypertension in patients with chronic kidney disease (CKD) is largely attributed to positive sodium balance. It is unclear how loop diuretics affect fluid volume compartments, especially with respect to their antihypertensive effect. METHODS: Subjects with CKD were administered a single therapeutically equivalent dose of an oral loop diuretic (furosemide or torsemide in randomized crossover design). We measured acute volume changes over 12 hours using biophysical and hormonal biomarkers and then 24-hour ambulatory blood pressure after daily diuretic therapy for 3 weeks. RESULTS: Single-dose administration of loop diuretic decreased extracellular water (ECW) by 1.7 L [95% confidence interval (95% CI) 1.2, 2.2, P < 0.001], total body water (TBW) by 1.2 L (95% CI 0.5, 1.9, P < 0.001), and increased natural log (ln) plasma renin activity (PRA) from -1.2 +/- 1.3 ng/mL/hour to -0.5 +/- 1.5 ng/mL/hour (P < 0.001). Daily loop diuretic administration resulted in reduced ECW from 24.2 +/- 6.4 L to 22.3 +/- 5.2 L (P = 0.02) and TBW from 54.3 +/- 12.7 L to 51.6 +/- 11.9 L (P < 0.001) in 1 week. After 3 weeks of diuretic therapy, whereas ECW reduction persisted at 22.8 +/- 5.1 L (P = 0.05), TBW trended toward baseline level at 52.7 +/- 11.8 L. A concomitant increase in ln PRA from -1.0 +/- 1.3 ng/mL/hour to 0.4 +/- 1.9 ng/mL/hour (P < 0.001) and ln plasma aldosterone (PA) from 2.0 +/- 0.8 ng/dL to 2.3 +/- 0.8 ng/dL (P < 0.005) and fall in ln brain natriuretic peptide (BNP) from 4.3 +/- 0.9 pg/mL to 3.7 +/- 1.0 pg/mL (P < 0.01) were seen at 1 week. Despite a trend toward restoration of TBW, changes in hormonal biomarkers were maintained at 3 weeks. Over these 3 weeks, furosemide reduced 24-hour ambulatory blood pressure from 147 +/- 17/78 +/- 11 mm Hg to 138 +/- 21/74 +/- 12 mm Hg (P = 0.021) and torsemide reduced it from 143 +/- 18/75 +/- 10 mm Hg to 133 +/- 19/71 +/- 10 mm Hg (P = 0.007). CONCLUSION: Patients with CKD have elevated extracellular fluid volume that can be corrected acutely with loop diuretics. Persistent diuretic use results in dynamic changes in ECW and other body fluid compartments that translate into chronic blood pressure reduction.

A double-blind randomized crossover trial of two loop diuretics in chronic kidney disease.

BACKGROUND: Torsemide has predictable absorption compared to furosemide. Thereby, torsemide results in more constant exposure to active drug. Our hypothesis was that this pharmacokinetic difference between these commonly used loop diuretics may translate into disparate antihypertensive responses in patients with chronic kidney disease (CKD). METHODS: We conducted a randomized, double-blind, two-period, crossover trial to compare the pharmacodynamics of torsemide and furosemide, in 14 subjects with stage 2 or 3 CKD. We first performed an inpatient study, where after the subjects were brought into sodium balance on a 200 mEq per day diet, a single bioequivalent dose of oral loop diuretic was administered with an intervening washout period. Measurements of urinary electrolytes were made. Subjects then participated in an outpatient study, wherein they received daily therapy for 3 weeks with the loop diuretics in random order. Twenty four-hour ambulatory blood pressure monitoring was performed before and after each drug to assess the antihypertensive response. RESULTS: In the inpatient phase, furosemide increased urinary sodium excretion from average (+/-SD) 199 +/- 49 mEq/day to 357 +/- 96 mEq/day and torsemide increased urinary sodium excretion from 213 +/- 79 mEq/day to 398 +/- 142 mEq/day. These differences between the diuretics were not significant, confirming bioequivalence. In the outpatient phase, furosemide reduced 24-hour ambulatory blood pressure from 147 +/- 17/78 +/- 11 mm Hg to 138 +/- 21/74 +/- 12 mm Hg (P = 0.021) and torsemide reduced it from 143 +/- 18/75 +/- 10 mm Hg to 133 +/- 19/71 +/- 10 mm Hg (P = 0.007). Although each diuretic was effective in reducing ambulatory blood pressure, the differences between diuretics were not statistically significant. CONCLUSION: Bioequivalent doses of torsemide and furosemide given in a randomized, double-blind design fail to demonstrate superiority of torsemide with respect to natriuresis or 24-hour ambulatory blood pressure control in subjects with stages 2 and 3 CKD.

Oxidative stress and renal injury with intravenous iron in patients with chronic kidney disease.

BACKGROUND: Intravenous iron is widely prescribed in patients with chronic kidney disease (CKD) and can cause oxidative stress. The relationship of oxidative stress and renal injury in patients with CKD is unknown. Whether renal injury can occur at a time point when transferrin is incompletely saturated is also unclear. METHODS: We conducted a randomized, open-label, parallel group trial to compare the oxidative stress induced by intravenous administration of 100 mg iron sucrose over 5 minutes and its protection with N-acetylcysteine (NAC) in 20 subjects with stage 3 or 4 CKD. Transferrin saturation was measured with urea polyacrylamide gel electrophoresis, oxidative stress by malondialdehyde (MDA) measurement by high-performance liquid chromatography, and renal injury by enzymuria and proteinuria. Reduced and oxidized glutathione and free radical scavengers as well as urinary monocyte chemoattractant protein-1 were also measured. RESULTS: Parenteral iron increased plasma concentration and urinary excretion rate of MDA, a biomarker of lipid peroxidation, within 15 to 30 minutes of iron sucrose administration. This was accompanied by enzymuria and increase in proteinuria. In contrast, saturation of transferrin was not maximally seen until 3 hours after the end of infusion. Oxidative stress, enzymuria and proteinuria were transient and were completely resolved in 24 hours. NAC reduced acute generation of systemic oxidative stress but failed to abrogate proteinuria or enzymuria. CONCLUSION: Intravenous iron produces oxidative stress that is associated with transient proteinuria and tubular damage. The rapid production of oxidative stress even when transferrin is not completely saturation suggests free iron independent mechanism(s) to be operative in producing oxidative stress and transient renal injury. Long-term implications of these findings need further study.