The validity of pathology codes for biopsy-confirmed kidney disease in the Danish National Patobank.

Background: This study validates the application of Systematized Nomenclature of Medicine second edition (SNOMED II) codes used to describe medical kidney biopsies in Denmark in encoded form, aiming to support robust epidemiological research on the causes, treatments and prognosis of kidney diseases. Methods: Kidney biopsy reports from 1 January 1998 to 31 December 2018 were randomly extracted from the Danish National Patobank, using SNOMED codes. A 5% sample was selected, and nephrologists assessed the corresponding medical records, assigning each case the applied clinical diagnoses. Sensitivity, specificity, positive predictive values (PPV), negative predictive values and Cohen's kappa coefficient for the retrieved SNOMED codes were calculated. Results: A total of 613 kidney biopsies were included. The primary clinical disease groups were glomerular disease (n = 368), tubulointerstitial disease (n = 67), renal vascular disease (n = 51), diabetic nephropathy (n = 51) and various renal disorders (n = 40). Several SNOMED codes were used to describe each clinical disease group and PPV for the combined SNOMED codes were high for glomerular disease (94%), diabetic nephropathy (85%) and systemic diseases affecting the kidney (96%). Conversely, tubulointerstitial disease (62%), renal vascular disease (60%) and other renal disorders (17%) showed lower PPV. Conclusions: SNOMED codes have a high PPV for glomerular diseases, diabetic nephropathy and systemic diseases affecting the kidney, in which they could be applied for future epidemiological research.

Patiromer to Reduce Albuminuria Through Increased Renin Angiotensin Aldosterone System Inhibition in Patients With CKD-A Feasibility Trial.

Introduction: We tested the feasibility of adding a potassium binder to enable increased renin angiotensin aldosterone system inhibition (RAASi) and reduce albuminuria in patients with chronic kidney disease (CKD). In a controlled trial design, a potassium binder was introduced exclusively in patients developing hyperkalemia after intensified RAASi, thereby mirroring clinical decision-making. Methods: We planned to include 140 patients aged 18 to 80 years with estimated glomerular filtration rate (eGFR) 25 to 60 ml/min per 1.73 m2, albuminuria, and a history of hyperkalemia to an open-label, randomized trial comparing treatment with or without patiromer alongside maximally tolerated RAASi. Patients were randomized only if developing a documented P-potassium >5.5 mmol/l during run-in with intensified RAASi (losartan/spironolactone). The primary end point was change in urine albumin-creatinine ratio (UACR). Results: Screening among 800,000 individuals with available laboratory results yielded just 317 candidates meeting major selection criteria during 18⅔ months, with 75 ultimately included. Among them, only 23 developed P-potassium >5.5 mmol/l, qualifying for randomization. Consequently, only 20 participants completed the study, falling short of the planned 98, precluding a significant effect on the primary outcome. Inclusion and randomization challenges stemmed from a limited pool of eligible patients for intensified RAASi at risk of hyperkalemia, along with a lower than expected incidence of hyperkalemia during run-in. Conclusion: Despite extensive screening efforts, few eligible patients were identified, and fewer developed hyperkalemia during run-in. Hence, a trial design limited to CKD patients at high hyperkalemia risk and including a run-in phase appears unlikely to provide evidence for a potential renal benefit from additional use of potassium binders.

Bone Turnover, Mineralization, and Volume Estimated by 18F-Sodium Fluoride PET/CT and Biomarkers in Chronic Kidney Disease: Mineral and Bone Disorder Compared with Bone Biopsy.

INTRODUCTION: Invasive bone biopsy to assess bone metabolism in patients with chronic kidney disease-mineral and bone disorder may be replaced by the noninvasive 18F-NaF PET/CT and biomarkers of bone metabolism. We aimed to compare parameters of bone turnover, mineralization, and volume assessed by bone biopsies with results derived from 18F-NaF PET/CT and biomarkers (bone-specific alkaline phosphatase, osteocalcin, fibroblast growth factor 23, and osteoprotegerin). METHODS: A cross-sectional study included 17 dialysis patients, and results from 18F-NaF PET/CT scans and the biomarkers were directly compared with the results of histomorphometric analyses of tetracycline double-labeled trans-iliac bone biopsies. RESULTS: Bone biopsies showed 40% high, 20% normal, and 40% low bone turnover. No biopsies had generalized abnormal mineralization, and the bone volume/total tissue volume was low in 80% and high in 7%. The pelvic skeletal plasma clearance (Ki) from 18F-NaF PET/CT correlated with bone turnover parameters obtained by bone biopsy (activation frequency: r = 0.82, p < 0.01; bone formation rate/bone surface: r = 0.81, p < 0.01), and Ki defined low turnover with high sensitivity (83%) and specificity (100%). CT-derived radiodensity correlated with bone volume, r = 0.82, p < 0.01. Of the biomarkers, only osteocalcin showed a correlation with turnover assessed by histomorphometry. CONCLUSION: In conclusion, 18F-NaF PET/CT may be applicable for noninvasive assessment of bone turnover and volume in CKD-MBD.

Hemodynamic, renal and hormonal effects of lung protective ventilation during robot-assisted radical prostatectomy, analysis of secondary outcomes from a randomized controlled trial.

BACKGROUND: Lung protective ventilation with low tidal volume (TV) and increased positive end-expiratory pressure (PEEP) can have unfavorable effects on the cardiovascular system. We aimed to investigate whether lung protective ventilation has adverse impact on hemodynamic, renal and hormonal variables. METHODS: In this randomized, single-blinded, placebo-controlled study, 24 patients scheduled for robot-assisted radical prostatectomy were included. Patients were equally randomized to receive either ventilation with a TV of 6 ml/IBW and PEEP of 10 cm H2O (LTV-h.PEEP) or ventilation with a TV of 10 ml/IBW and PEEP of 4 cm H2O (HTV-l.PEEP). Before, during and after surgery, hemodynamic variables were measured, and blood and urine samples were collected. Blood samples were analyzed for plasma concentrations of electrolytes and vasoactive hormones. Urine samples were analyzed for excretions of electrolytes and markers of nephrotoxicity. RESULTS: Comparable variables were found among the two groups, except for significantly higher postoperative levels of plasma brain natriuretic peptide (p = 0.033), albumin excretion (p = 0.012) and excretion of epithelial sodium channel (p = 0.045) in the LTV-h.PEEP ventilation group compared to the HTV-l.PEEP ventilation group. In the combined cohort, we found a significant decrease in creatinine clearance (112.0 [83.4;126.7] ml/min at baseline vs. 45.1 [25.4;84.3] ml/min during surgery) and a significant increase in plasma concentrations of renin, angiotensin II, and aldosterone. CONCLUSION: Lung protective ventilation was associated with minor adverse hemodynamic and renal effects postoperatively. All patients showed a substantial but transient reduction in renal function accompanied by activation of the renin-angiotensin-aldosterone system. TRIAL REGISTRATION: ClinicalTrials, NCT02551341 . Registered 13 September 2015.

Technetium-99m-MAG3 and technetium-99m-DTPA: Renal clearance measured by the constant infusion technique - Old news?

BACKGROUND: Accurate, precise and straightforward methods for measuring glomerular filtration rate (GFR) and/or renal plasma flow (RPF) are still in demand today. The time-consuming constant infusion technique (CIT) is the gold standard and preferred for research, whereas the simple, but less precise, single injection technique (SIT) is used in clinical settings. This study investigated the use of 99m Tc-DTPA and 99m Tc-MAG3 by CIT as a measure of renal function. We developed and evaluated a model to balance the primer dose and infusion rate in an attempt to obtain plasma steady state as quickly as possible. METHODS: 14 healthy subjects received 99m Tc-DTPA and 6 hypertensive patients received 99m Tc-MAG3 in a standardized protocol. All participants had an eGFR above 60 ml/min and none had fluid retention. An intravenous primer injection of the relevant tracer was followed by a sustained infusion over 4.5 h with the same radiopharmaceutical. Blood and urine samples were collected at fixed intervals. RESULTS: 99m Tc-DTPA clearance reached steady state after 210 min (plasma clearance 78 ± 18 ml/min, urine clearance 110 ± 28 ml/min), whereas 99m Tc-MAG3  clearance achieved steady state after 150 min (plasma clearance 212 ± 56 ml/min, urine clearance 233 ± 59 ml/min). CONCLUSION: Constant infusion technique with fixed primer and infusion rate using 99m Tc-MAG3 is feasible for research purposes. The longer time for reaching plasma steady state using 99m Tc-DTPA makes CIT with this tracer less optimal. If the primer/sustained balance can be optimized, for example using a priori SIT information, 99m Tc-DTPA as tracer for CIT may also be feasible.

Prednisolone treatment in acute interstitial nephritis (PRAISE) - protocol for the randomized controlled trial.

BACKGROUND: Acute interstitial nephritis (AIN) is an important and common cause of acute renal failure. There are no generally accepted guidelines for the treatment of AIN, due to the lack of prospective randomized trials. Since AIN is characterized by an enhanced immune response, immunosuppressive treatment could potentially improve prognosis by attenuating inflammation and subsequent fibrosis. Despite the limited evidence of effects of steroids and potential adverse effects, prednisolone is frequently used in the treatment of AIN and there is a strong need for clinical trials on the effects of immunosuppression, including steroids, in the treatment of AIN. We aimed to evaluate the effectiveness of prednisolone treatment in AIN, and hypothesized a positive effect of prednisolone treatment on renal function in AIN. METHODS: The study is a randomized, controlled, prospective, open label multicenter study, including incident adult patients with biopsy proven AIN. Patients will be randomized 1:1 to one of 2 treatment regimens: A. No prednisolone treatment (control group) and B. B) Oral prednisolone treatment staring with 60 mg daily tapered over 8 weeks. One hundred ten patients (55 in each group) are planned to be included and followed for 1 year. Primary outcome is renal function estimated by eGFR 3 months after inclusion. Secondary outcomes are renal function after 12 months and need for renal replacement therapy and quality of life after 3 and 12 months. In addition, with-in prednisolone group analysis are performed to estimate the importance of treatment delay. Exploratory analyses include analysis of biomarkers in urine and plasma and the evaluation of these biomarkers in relation to renal prognosis and re-evaluation of renal biopsies to identify possible renal prognostic factors. DISCUSSION: Strengths and possible limitations in the design are evaluated. The study will provide important information on the effects of prednisolone treatment in AIN and as well as prognostic information relevant for future use of biomarkers and histology. Ultimately, this would lead to improved and evidence based clinical guidelines for the treatment of AIN. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04376216 (Retrospectively registered on May 6, 2020).

Effect of Vitamin D Supplementation on Markers of Vascular Function: A Systematic Review and Individual Participant Meta-Analysis.

BACKGROUND: Low 25-hydroxyvitamin D levels are associated with an increased risk of cardiovascular events, but the effect of vitamin D supplementation on markers of vascular function associated with major adverse cardiovascular events is unclear. METHODS AND RESULTS: We conducted a systematic review and individual participant meta-analysis to examine the effect of vitamin D supplementation on flow-mediated dilatation of the brachial artery, pulse wave velocity, augmentation index, central blood pressure, microvascular function, and reactive hyperemia index. MEDLINE, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, and http://www.ClinicalTrials.gov were searched until the end of 2016 without language restrictions. Placebo-controlled randomized trials of at least 4 weeks duration were included. Individual participant data were sought from investigators on included trials. Trial-level meta-analysis was performed using random-effects models; individual participant meta-analyses used a 2-stage analytic strategy, examining effects in prespecified subgroups. 31 trials (2751 participants) were included; 29 trials (2641 participants) contributed data to trial-level meta-analysis, and 24 trials (2051 participants) contributed to individual-participant analyses. Vitamin D3 daily dose equivalents ranged from 900 to 5000 IU; duration was 4 weeks to 12 months. Trial-level meta-analysis showed no significant effect of supplementation on macrovascular measures (flow-mediated dilatation, 0.37% [95% confidence interval, -0.23 to 0.97]; carotid-femoral pulse wave velocity, 0.00 m/s [95% confidence interval, -0.36 to 0.37]); similar results were obtained from individual participant data. Microvascular function showed a modest improvement in trial-level data only. No consistent benefit was observed in subgroup analyses or between different vitamin D analogues. CONCLUSIONS: Vitamin D supplementation had no significant effect on most markers of vascular function in this analysis.

Changes in urinary excretion of water and sodium transporters during amiloride and bendroflumethiazide treatment.

AIM: To quantify changes in urinary excretion of aquaporin2 water channels (u-AQP2), the sodium-potassium-chloride co-transporter (u-NKCC2) and the epithelial sodium channels (u-ENaC) during treatment with bendroflumethiazide (BFTZ), amiloride and placebo. METHODS: In a randomized, double-blinded, placebo-controlled, 3-way crossover study we examined 23 healthy subjects on a standardized diet and fluid intake. The subjects were treated with amiloride 5 mg, BFTZ 1.25 mg or placebo twice a day for 4.5 d before each examination day. On the examination day, glomerular filtration rate was measured by the constant infusion clearance technique with (51)Cr-EDTA as reference substance. To estimate the changes in water transport via AQP2 and sodium transport via NKCC2 and ENaC, u-NKCC2, the gamma fraction of ENaC (u-ENaCγ), and u-AQP2 were measured at baseline and after infusion with 3% hypertonic saline. U-NKCC2, u-ENaCγ, u-AQP2 and plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensin II (p-ANG II) and aldosterone (p-Aldo) were measured, by radioimmunoassay. Central blood pressure was estimated by applanation tonometry and body fluid volumes were estimated by bio-impedance spectroscopy. General linear model with repeated measures or related samples Friedman's two-way analysis was used to compare differences. Post hoc Bonferroni correction was used for multiple comparisons of post infusion periods to baseline within each treatment group. RESULTS: At baseline there were no differences in u-NKCC2, u-ENaCγ and u-AQP2. PRC, p-Ang II and p-Aldo were increased during active treatments (P < 0.001). After hypertonic saline, u-NKCC2 increased during amiloride (6% ± 34%; P = 0.081) and increased significantly during placebo (17% ± 24%; P = 0.010). U-AQP2 increased significantly during amiloride (31% ± 22%; P < 0.001) and placebo (34% ± 27%; P < 0.001), while u-NKCC2 and u-AQP2 did not change significantly during BFTZ (-7% ± 28%; P = 0.257 and 5% ± 16%; P = 0.261). U- ENaCγ increased in all three groups (P < 0.050). PRC, AngII and p-Aldo decreased to the same extent, while AVP increased, but to a smaller degree during BFTZ (P = 0.048). cDBP decreased significantly during BFTZ (P < 0.001), but not during amiloride or placebo. There were no significant differences in body fluid volumes. CONCLUSION: After hypertonic saline, u-NKCC2 and u-AQP2 increased during amiloride, but not during BFTZ. Lower p-AVP during BFTZ potentially caused less stimulation of NKCC2 and AQP2 and subsequent lower reabsorption of water and sodium.

Effect of nebivolol on renal nitric oxide availability and tubular function in patients with essential hypertension.

AIMS: Nebivolol is a selective ß1 -receptor antagonist with vasodilating properties. In patients with essential hypertension, we tested the hypothesis that nebivolol increases systemic and renal nitric oxide (NO) availability using L-N(G) -monomethyl arginine (L-NMMA) as an inhibitor of NO production. METHODS: In a randomized, placebo-controlled, crossover study, patients with essential hypertension were treated with nebivolol for five days, along with a standardized diet and fluid intake. We examined the acute effects of systemic NO synthase inhibition with L-NMMA on brachial blood pressure (bBP), pulse wave velocity (PWV) and central blood pressure (cBP) estimated by applanation tonometry, glomerular filtration rate (GFR), fractional excretion of sodium (FENa ), urinary excretion of both aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaCγ ), and plasma concentrations of nitrate/nitrite (p-NOx ) and vasoactive hormones after five days' treatment with placebo and nebivolol. RESULTS: Nebivolol significantly reduced PWV, bBP, cBP and plasma renin, angiotensin II and aldosterone concentrations. The renal parameters, p-NOx and plasma arginine vasopressin concentration were not changed by nebivolol. There was no difference between nebivolol and placebo in the response to L-NMMA, with LMMA inducing a similar increase in PWV, bBP and cBP and a similar decrease in GFR, uAQP2 and u-ENaCγ and FENa [mean change -0.62% (95% confidence interval {CI} -0.40 to -0.84) during placebo vs. -0.57% (95% CI -0.46 to -0.68; P = 0.564) during nebivolol treatment]. Vasoactive hormones were changed to a similar extend by L-NMMA during administration of nebivolol and placebo. CONCLUSIONS: Nebivolol did not change p-NOx , and inhibition of NO synthesis induced the same response in blood pressure, GFR, renal tubular function and vasoactive hormones during nebivolol and placebo. Thus, the data did not support the hypothesis that nebivolol changes vascular and renal NO availability in patients with essential hypertension.

Abnormal urinary excretion of NKCC2 and AQP2 in response to hypertonic saline in chronic kidney disease: an intervention study in patients with chronic kidney disease and healthy controls.

BACKGROUND: Renal handling of sodium and water is abnormal in chronic kidney disease (CKD). The aim of this study was to test the hypothesis that abnormal activity of the aquaporin-2 water channels (AQP2), the sodium-potassium-2chloride transporter (NKCC2) and/or the epithelial sodium channels (ENaC) contribute to this phenomenon. METHODS: 23 patients with CKD and 24 healthy controls at baseline and after 3% saline infusion were compared. The following measurements were performed: urinary concentrations of AQP2 (u-AQP2), NKCC2 (u-NKCC2), ENaC (u-ENaCγ), glomerular filtration rate (GFR) estimated by 51Cr-EDTA clearance, free water clearance (CH2O), urinary output (UO), fractional excretion of sodium (FENa), plasma concentrations of AVP, renin (PRC), Angiotensin II (ANG II), Aldosterone (Aldo) and body fluid volumes. RESULTS: At baseline, GFR was 34 ml/min in CKD patients and 89 ml/ml in controls. There were no significant differences in u-AQP2, u-NKCC2 or u-ENaCγ, but FENa, p-Aldo and p-AVP were higher in CKD patients than controls. In response to hypertonic saline, patients with CKD had an attenuated decrease in CH2O and UO. A greater increase in U-AQP2 was observed in CKD patients compared to controls. Furthermore, u-NKCC2 increased in CKD patients, whereas u-NKCC2 decreased in controls. Body fluid volumes did not significantly differ. CONCLUSIONS: In response to hypertonic saline, u-NKCC2 increased, suggesting an increased sodium reabsorption via NKCC2 in patients with CKD. U-AQP2 increased more in CKD patients, despite an attenuated decrease in CH2O. Thus, though high levels of p-AVP and p-Aldo, the kidneys can only partly compensate and counteract acute volume expansion due to a defective tubular response. TRIAL REGISTRATION: Clinical trial no: NCT01623661. Date of trial registration: 18.06.2012.

Cardiovascular effects of cholecalciferol treatment in dialysis patients--a randomized controlled trial.

BACKGROUND: Patients on chronic dialysis are at increased risk of vitamin D deficiency. In observational studies plasma 25-hydroxyvitamin D (p-25(OH) D) levels are inversely correlated with plasma BNP and adverse cardiovascular outcomes. Whether a causal relation exists has yet to be established. The aim of this study was to test the hypothesis that cholecalciferol supplementation improves cardiac function and reduces blood pressure (BP) and pulse wave velocity (PWV) in patients on chronic dialysis. METHODS: In a randomized, placebo-controlled, double-blind study, we investigated the effect of 75 µg (3000 IU) cholecalciferol daily for 6 months, in patients on chronic dialysis. We performed two-dimensional echocardiography, with doppler and tissue-doppler imaging, 24-h ambulatory BP (24-h BP), PWV, augmentation index (AIx), central BP (cBP) and brain natriuretic peptide (BNP) measurements at baseline and after 6 months. RESULTS: Sixty-four patients were allocated to the study. Fifty dialysis patients with a mean age of 68 years (range: 46-88) and baseline p-25(OH) D of 28 (20;53) nmol/l completed the trial. Cholecalciferol increased left ventricular (LV) volume, but had no impact on other parameters regarding LV structure or left atrial structure. LV systolic function, LV diastolic function, PWV, cBP, AIx and BNP were not changed in placebo or cholecalciferol group at follow-up. 24-h BP decreased significantly in placebo group and tended to decrease in cholecalciferol group without any difference between treatments. CONCLUSION: Six months of cholecalciferol treatment in patients on chronic dialysis did not improve 24-h BP, arterial stiffness or cardiac function. TRIAL REGISTRATION: NCT01312714, Registration Date: March 9, 2011.

Effect of atorvastatin on renal NO availability and tubular function in patients with stage II-III chronic kidney disease and type 2 diabetes.

BACKGROUND: Statins have beneficial effects on cardiovascular morbidity and mortality independently of reduction of plasma cholesterol. PURPOSE AND METHODS: In patients with type 2 diabetes and nephropathy, chronic kidney disease stage II-III, we tested the hypothesis that atorvastatin increased systemic and renal nitric oxide (NO) availability using L-NMMA as an inhibitor of NO production. We performed a randomized, placebo-controlled, crossover study, using atorvastatin/placebo treatment for five days with a standardized diet and fluid intake. We measured brachial BP (bBP), central BP (cBP), GFR, urinary output (OU), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary excretion of albumin (UAER and UACR), AQP2 (u-AQP2) and ENaC (u-ENaCγ) and plasma concentrations of vasoactive hormones: renin, angiotensin II, aldosterone, arginine vasopressin, endothelin-1 and brain natriuretic peptide. RESULTS: During atorvastatin and placebo treatment, L-NMMA infusion, changed the effect variables significantly, but to the same extent, i.e. an increase in bBP and cBP, and a decrease in GFR, OU, CH2O, FENa, u-AQP2 and u-ENaCγ. In addition, renin and angiotensin II was reduced, aldosterone increased, and vasopressin, endothelin-1 and brain natriuretic hormone unchanged. CONCLUSION: During, atorvastatin and placebo treatment, inhibition of nitric oxide synthesis induced the same response in brachial and central blood pressure, GFR, renal tubular function and vasoactive hormones. Thus, atorvastatin did not change nitric oxide availability in type 2 diabetics with nephropathy.

Effect of volume expansion with hypertonic- and isotonic saline and isotonic glucose on sodium and water transport in the principal cells in the kidney.

BACKGROUND: The renal distal nephron plays an important role in the maintenance of sodium balance, extra cellular volume and blood pressure. The degree of water transport, via aquaporin2 water channels (AQP2), and sodium transport, via epithelial sodium channels (ENaC) in renal collecting duct principal cells are reflected by the level of urinary excretion of AQP2 (u-AQP2) and the γ-fraction of ENaC (u-ENaCγ). The effects of an acute intravenous volume load with isotonic saline, hypertonic saline and glucose on u-AQP2, u-ENaCγ and underlying mechanisms have never been studied in a randomized, placebo-controlled trial in healthy humans. METHODS: We studied the effects of 0.9% saline (23 ml/kg), 3% saline (7 ml/kg) and 5% glucose (23 ml/kg) on u-AQP2 and u-ENaCγ, fractional sodium excretion (FENa), free water clearance (CH2O), and plasma concentrations of vasopressin (AVP), renin (PRC), angiotensin II (ANG II) and aldosterone (Aldo) in a randomized, crossover study of 23 healthy subjects, who consumed a standardized diet, regarding calories, sodium and fluid for 4 days before each examination day. RESULTS: After isotonic saline infusion, u-AQP2 increased (27%). CH2O and u-ENaCγ were unchanged, whereas FENa increased (123%). After hypertonic saline infusion, there was an increase in u-AQP2 (25%), u-ENaCγ (19%) and FENa (96%), whereas CH2O decreased (-153%). After isotonic glucose infusion, there was a decrease in u-AQP2 (-16%), ENaCγ (-10%) and FENa (-44%) whereas CH2O increased (164%). AVP remained unchanged after isotonic saline and glucose, but increased after hypertonic saline (139%). PRC, AngII and p-Aldo decreased after isotonic and hypertonic saline infusion, but not after glucose infusion. CONCLUSIONS: Volume expansion with 3% and 0.9% saline increased u-AQP2, while isotonic glucose decreased u-AQP2. Infusion of hypertonic saline increased u-ENaCγ, whereas u-ENaCγ was not significantly changed after isotonic saline and tended to decrease after glucose. Thus, the transport of water and sodium is changed both via the aquaporin 2 water channels and the epithelial sodium channels during all three types of volume expansion to regulate and maintain water- and sodium homeostasis in the body. TRIAL REGISTRATION: Clinical Trial no: NCT01414088.

Effect of paricalcitol on renin and albuminuria in non-diabetic stage III-IV chronic kidney disease: a randomized placebo-controlled trial.

BACKGROUND: Vitamin D receptor activators reduce albuminuria, and may improve survival in chronic kidney disease (CKD). Animal studies suggest that these pleiotropic effects of vitamin D may be mediated by suppression of renin. However, randomized trials in humans have yet to establish this relationship. METHODS: In a randomized, placebo-controlled, double-blinded crossover study, the effect of oral paricalcitol (2 µg/day) was investigated in 26 patients with non-diabetic, albuminuric stage III-IV CKD. After treatment, plasma concentrations of renin (PRC), angiotensin II (AngII) and aldosterone (Aldo) were measured. GFR was determined by 51Cr-EDTA clearance. Assessment of renal NO dependency was performed by infusion of NG-monomethyl-L-arginine (L-NMMA). Albumin excretion rate (AER) was analyzed in 24-h urine and during 51Cr-EDTA clearance. RESULTS: Paricalcitol did not alter plasma levels of renin, AngII, Aldo, or urinary excretion of sodium and potassium. A modest reduction of borderline significance was observed in AER, and paricalcitol abrogated the albuminuric response to L-NMMA. CONCLUSIONS: In this randomized, placebo-controlled trial paricalcitol only marginally decreased AER and did not alter circulating levels of renin, AngII or Aldo. The abrogation of the rise in albumin excretion by paricalcitol during NOS blockade may indicate that favourable modulation of renal NO dependency could be involved in mediating reno-protection and survival benefits in CKD. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01136564.

Effect of cholecalciferol supplementation during winter months in patients with hypertension: a randomized, placebo-controlled trial.

BACKGROUND: Low 25-hydroxy-vitamin D (25(OH)D) levels are inversely related to blood pressure (BP) and have been associated with incident hypertension. In people living at northern latitudes diminished cholecalciferol synthesis in the winter increases the risk of vitamin D deficiency. We wanted to test the hypothesis that daily cholecalciferol supplementation in the winter lowers BP in patients with hypertension. METHODS: We investigated the effect of 75 µg (3,000 IU) cholecalciferol per day in a randomized, placebo-controlled, double-blind study in 130 hypertensive patients residing in Denmark (56º N). Ambulatory BP (24-h BP) and arterial stiffness were measured before and after 20 weeks of treatment, that took place between October and March. RESULTS: A total of 112 patients (mean age 61 ± 10) with a baseline p-25(OH)D of 23 ± 10 ng/ml completed the study. Compared with placebo, a nonsignificant 3/1 mm Hg (P = 0.26/0.18) reduction was found in 24-h BP. In patients with vitamin D insufficiency (<32 ng/ml) at baseline (n = 92), 24-h BP decreased by 4/3 mm Hg (P = 0.05/0.01). Central BP (CBP) estimated by applanation tonometry and calibrated with a standardized office BP was reduced by 7/2 mm Hg (P = 0.007/0.15) vs. placebo. No differences in carotid-femoral pulse wave velocity (PWV) or central augmentation index (AIx) were found between treatment arms. CONCLUSIONS: Cholecalciferol supplementation, by a dose that effectively increased vitamin D levels, did not reduce 24-h BP, although central systolic BP decreased significantly. In a post-hoc subgroup analysis of 92 subjects with baseline p-25(OH)D levels <32 ng/ml, significant decreases in 24-h systolic and diastolic BP occurred during cholecalciferol supplementation.