Impact of hyperparathyroidism on allograft histology and function after kidney transplantation: Rethinking its causal role in graft dysfunction.

INTRODUCTION: The causal relationship between hyperparathyroidism and kidney graft dysfunction remains inconclusive. Applying Bradford-Hill's temporality and consistency causation principles, we assessed the effect of parathyroid hormone (iPTH) on graft histology and eGFR trajectory on kidney transplant recipients (KTRs) with normal time-zero graft biopsies. METHODS: Retrospective cohort study evaluating the effect of hyperparathyroidism on interstitial fibrosis and tubular atrophy (IF/TA) development in 1232 graft biopsies. Pre-transplant hyperparathyroidism was categorized by KDIGO or KDOQI criteria, and post-transplant hyperparathyroidism by iPTH >1× and >2× the URL 1 year after transplantation. RESULTS: We included 325 KTRs (56% female, age 38 ± 13 years, follow-up 4.2 years [IQR: 2.7-5.8]). Based on pre-transplant iPTH levels, 26% and 66% exceeded the KDIGO and KDOQI targets, respectively. There were no significant differences in the development of >25% IF/TA between KTRs with pre-transplant iPTH levels above and within target range according to KDIGO (53% vs. 62%, P = .16, HR.94 [95% CI:.67-1.32]) and KDOQI (60% vs. 60%, P = 1.0, HR 1.19 [95% CI:.88-1.60]) criteria. Similarly, there were no differences when using 1 year post-transplant iPTH cut-offs > 88 pg/mL (58% vs. 64%, P = .33) and > 176 pg/mL (55% vs. 62%, P = .19). After adjusting for confounders, no significant differences were observed in eGFR trajectories among the iPTH strata. CONCLUSION: In young KTRs who received a healthy graft, no association was found between increased pre- and post-transplant iPTH levels and graft dysfunction, as assessed histologically and through eGFR trajectory. The concept of hyperparathyroidism as a risk factor for graft dysfunction in recipients at low risk requires reevaluation.

Effect of Kidney transplantation on cyst growth in autosomal dominant polycystic kidney disease.

BACKGROUND: In patients with autosomal dominant polycystic kidney disease (ADPKD), there is limited evidence of the rate of cyst progression after kidney transplantation. AIMS: To compare the height-adjusted total kidney volume (Ht-TKV) before and after transplantation in kidney transplant recipients (KTR) with -ADPKD. MATERIALS AND METHODS: Retrospective cohort study. The estimate of Ht-TKV was calculated by the ellipsoid volume equation using measurements from CT or yearly MRI scans before and after transplantation. RESULTS: We included 30 patients with -ADPKD who underwent kidney transplantation (age 49 ± 10.1 years, 11 (37%) females, dialysis vintage 3 (1 - 6) years, and 4 (13%) underwent unilateral nephrectomy during the peritransplant period). The median follow-up time was 5 years (range 2 - 16 years). Transplantation was associated with a significant decrease in Ht-TKV after transplantation in 27 (90%) KTR. Median Ht-TKV decreased from 1,708 (IQR 1,100 - 2,350) mL/m to 710 (IQR 420 - 1,380) mL/m after 6 years of follow-up (p < 0.001), with a mean Ht-TKV change rate per year after transplantation of -1.4, -11.8, -9.7, -12.7, -7.0, and -9.4% after 1, 2, 3, 4, 5, and 6 years, respectively. Even in 2 (7%) KTR without regression, the annual growth was < 1.5% per year after transplantation. CONCLUSION: Kidney transplantation reduced Ht-TKV after the first 2 years of transplantation, and this decline was continuous for more than 6 years of follow-up.

What did we learn about coronavirus disease-19-associated acute kidney injury during the pandemic?

Initial reports suggested that kidney involvement after coronavirus disease 19 (COVID-19) infection was uncommon, but this premise appears to be incorrect. Acute kidney injury can occur through various mechanisms and complicate the course of up to 25% of patients with COVID-19 hospitalized in our Institution, and of over 50% of those on invasive mechanical ventilation. Mechanisms of injury include direct kidney injury and predominantly tubular, although glomerular injury has been reported, and resulting from severe hypoxic respiratory failure, secondary infection, and exposure to nephrotoxic drugs. The mainstay of treatment remains the prevention of progressive kidney damage and, in some cases, the use of renal replacement therapy. Although the use of blood purification techniques has been proposed as a potential treatment, results to date have not been conclusive. In this manuscript, the mechanisms of kidney injury by COVID-19, risk factors, and the mainstays of treatment are reviewed.

Sorafenib as a second-line treatment in metastatic renal cell carcinoma in Mexico: a prospective cohort study.

BACKGROUND: Sequential inhibition of the vascular endothelial growth factor (VEGF) pathway with sorafenib could be useful for patients with metastatic renal cell carcinoma (RCC). Our aim was to determine the activity and tolerability of sorafenib as a second-line therapy in advanced RCC initially treated with a different VEGF-tyrosine kinase inhibitor (TKI). METHODS: A prospective observational cohort in Mexico (2012-2019). We included 132 subjects with metastatic RCC and who had progression despite treatment with sunitinib. The primary end-point was time to disease progression as evaluated every 12-16 weeks. RESULTS: The mean age of the cohort was 59 years (interquartile range [IQR] 50-72), 96 (73%) were men, and 48 (36%) had a favorable prognosis according to the IMDC (International Metastatic RCC Database Consortium) prognostic model. The median progression-free survival (PFS) and overall-survival after the introduction of sorafenib treatment was 8.6 months (95% confidence interval [CI]: 6.7-10.5) and 40 months (95% CI: 34.5-45.4) respectively. The median overall survival from RCC diagnosis to death was 71 months (95% CI: 58.2-83.8). On multivariable analyses, age > 65 years was associated with a longer PFS (HR 0.51; 95% CI: 0.31-0.86; p = 0.018). The median PFS in subjects aged > 65 years was longer compared to subjects ≤65 years (14.0 [95% CI: 9.2-18.8] vs. 7.2 months [95% CI: 5.3-9.1]; p = 0.012). Adverse events grade ≥ 3 associated with sorafenib occurred in 38 (29%) patients. CONCLUSION: Sequential inhibition of VEGF with sorafenib as a second-line treatment may benefit patients with metastatic RCC, especially in subjects > 65 years old.

Prolonged Intermittent Renal Replacement Therapy for Acute Kidney Injury in COVID-19 Patients with Acute Respiratory Distress Syndrome.

INTRODUCTION: Patients with acute respiratory distress syndrome (ARDS) secondary to COVID-19 frequently develop severe acute kidney injury (AKI). Although continuous renal replacement therapy is the standard of care for critically ill patients, prolonged intermittent renal replacement therapy (PIRRT) may be a feasible option. We aimed to describe the tolerability and security of PIRRT treatments in COVID-19 patients with ARDS who required mechanical ventilation and developed severe AKI. METHODS: We prospectively analyzed patients who underwent PIRRT treatments at a COVID-19 reference hospital in Mexico City. Intradialytic hypotension was defined as a systolic blood pressure decrease of ≥20 mm Hg or an increase of 100% in vasopressor dose. RESULTS: We identified 136 AKI cases (60.7%) in 224 patients admitted to the intensive care unit. Among them, 21 (15%) underwent PIRRT (130 sessions) due to stage 3 AKI. The median age of the cohort was 49 (range 36-73) years, 17 (81%) were male, 7 (33%) had diabetes, and the median time between symptoms onset and PIRRT initiation was 12 (interquartile range [IQR] 7-14) days. The median of PIRRT procedures for each patient was 5 (IQR 4-9) sessions. In 108 (83%) PIRRT sessions, the total ultrafiltration goal was achieved. In 84 (65%) PIRRT procedures, there was a median increase in norepinephrine dose of +0.031 mcg/kg/min during PIRRT (IQR 0.00 to +0.07). Intradialytic hypotensive events occurred in 56 (43%) procedures. Fifteen (12%) PIRRT treatments were discontinued due to severe hypotension. Vasopressor treatment at PIRRT session onset (OR 6.2, 95% CI 1.4-28.0, p: 0.02) and a pre-PIRRT lactate ≥3.0 mmol/L (OR 4.63, 95% CI 1.3-12.8, p: 0.003) were independently and significantly associated with the risk of hypotension during PIRRT. During follow-up, 11 patients (52%) recovered from AKI and respiratory failure and 9 (43%) died. Several adaptations to our PIRRT protocol during the COVID-19 outbreak are presented. CONCLUSIONS: PIRRT was feasible in the majority of COVID-19 patients with ARDS and severe AKI, despite frequent transitory intradialytic hypotensive episodes. PIRRT may represent an acceptable alternative of renal replacement therapy during the COVID-19 outbreak.

Community- and Hospital-Acquired Acute Kidney Injury in COVID-19: Different Phenotypes and Dismal Prognosis.

INTRODUCTION: Acute kidney injury (AKI) is common in coronavirus disease 2019 (COVID-19). It is unknown if hospital-acquired AKI (HA-AKI) and community-acquired AKI (CA-AKI) convey a distinct prognosis. METHODS: The study aim was to evaluate the incidence and risk factors associated with both CA-AKI and HA-AKI. Consecutive patients hospitalized at a reference center for COVID-19 were included in this prospective cohort study. RESULTS: We registered 349 (30%) AKI episodes in 1,170 hospitalized patients, 224 (19%) corresponded to CA-AKI, and 125 (11%) to HA-AKI. Compared to patients with HA-AKI, subjects with CA-AKI were older (61 years [IQR 49-70] vs. 50 years [IQR 43-61]), had more comorbidities (hypertension [44 vs. 26%], CKD [10 vs. 3%]), higher Charlson Comorbidity Index (2 points [IQR 1-4] vs. 1 point [IQR 0-2]), and presented to the emergency department with more severe disease. Mortality rates were not different between CA-AKI and HA-AKI (119 [53%] vs. 63 [50%], p = 0.66). In multivariate analysis, CA-AKI was strongly associated to a history of CKD (OR 4.17, 95% CI 1.53-11.3), hypertension (OR 1.55, 95% CI 1.01-2.36), Charlson Comorbidity Index (OR 1.16, 95% CI 1.02-1.32), and SOFA score (OR 2.19, 95% CI 1.87-2.57). HA-AKI was associated with the requirement for mechanical ventilation (OR 68.2, 95% CI 37.1-126), elevated troponin I (OR 1.95, 95% CI 1.01-3.83), and glucose levels at admission (OR 1.05, 95% CI 1.02-1.08). DISCUSSION/CONCLUSIONS: CA-AKI and HA-AKI portend an adverse prognosis in CO-VID-19. Nevertheless, CA-AKI was associated with a higher comorbidity burden (including CKD and hypertension), while HA-AKI occurred in younger patients by the time severe multiorgan disease developed.

Clinical factors associated with early and persistent hypocalcaemia after parathyroidectomy in patients on dialysis with severe hyperparathyroidism.

AIM: Severe hypocalcaemia following parathyroidectomy for secondary or tertiary hyperparathyroidism (SHPT/THPT) is scarcely studied. We aimed to describe and identify risk factors for early and persistent hypocalcaemia after parathyroidectomy. METHODS: Retrospective pair-matched cohort study. We assessed 87 dialysis patients with SHPT (n = 73) or THPT (n = 14) paired with 146 subjects with primary hyperparathyroidism (PHPT) who underwent parathyroidectomy and were followed for 12 months. Early severe hypocalcaemia was defined as a free Ca ≤0.8 mmol/L [3.2 mg/dl] or corrected Ca ≤1.87 mmol/L [7.5 mg/dl] within 48 h. After parathyroidectomy and persistent hypocalcaemia, as an elemental Ca intake >3.0 g/day to achieve corrected Ca >2 mmol/L [8.0 mg/dl]. RESULTS: Early severe hypocalcaemia occurred in 77% (67/87) versus 6.8% (10/146) of subjects with SHPT/THPT and PHPT, respectively (p < .001). In SHPT/THPT cases, persistent hypocalcaemia occurred in 77% (49/64) and 64% (35/54) after 6 and 12 months of parathyroidectomy, respectively. In PHPT cases, persistent hypocalcaemia occurred in 6.8% (10/146) after 4-12 months of parathyroidectomy. Preoperative serum alkaline phosphatase (ALP) was the only risk factor associated to early severe hypocalcaemia (OR 7.3, 95% C.I. 1.7-10.9, p = .006) and persistent hypocalcaemia (OR 7.1, 95% C.I: 2.1-14.2, p = .011). Subjects with persistently low intact parathormone (iPTH) (<5.3 pmol/L [50 ng/ml]), suggestive of adynamic bone disease) showed higher Ca increases and less oral calcium requirements compared to those who progressively increased iPTH after parathyroidectomy. CONCLUSION: Early and persistent hypocalcaemia after parathyroidectomy in severe HPT were a common event associated directly to preoperative ALP levels. Subjects with persistently low postoperative iPTH normalized serum Ca more frequently after 1 year of follow up.

Uric Acid, Vascular Stiffness, and Chronic Kidney Disease: Is There a Link?

Controversy exists with regard to the causal role of hyperuricemia in chronic kidney disease. Vascular stiffness may be the link that explains the relation between hyperuricemia and kidney disease. Hyperuricemia is associated with a number of effects on the vascular endothelium and vascular smooth muscle cells, including an increase in oxidative stress, production of vasoconstrictors, and changes on the structural properties of the large artery wall. Observational evidence in large epidemiological cross-sectional studies suggests that there is an independent association between uric acid and arterial stiffness. The limited evidence from cohort studies or clinical trials does not support treatment of hyperuricemia to reduce vascular stiffness in order to prevent kidney disease. Nevertheless, vascular stiffness may be a valid, reproducible, and useful surrogate endpoint. At this point there seems to be sufficient evidence to warrant larger clinical trials to determine whether lowering uric acid concentrations would be useful for prevention or treatment of vascular stiffness and, subsequently, of cardiovascular and kidney diseases. Video Journal Club 'Cappuccino with Claudio Ronco' at http://www.karger.com/?doi=452726.

Urinary neutrophil gelatinase-associated lipocalin predicts graft loss after acute kidney injury in kidney transplant.

OBJECTIVE: Establish the prognostic value for graft loss of urinary neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule-1 (uKIM-1), interleukin-18 (uIL-18), and heat shock protein 72 (uHsp72) in kidney transplant recipients (KTR) with acute kidney injury (AKI). METHODS: Biomarkers were measured in 67 KTR with AKI caused by different entities. RESULTS: After 1 year, 11 KTR with graft loss had higher uNGAL compared to KTR without loss (p < 0.001). There were no differences for uKIM-1, uIL-18 and uHsp-72. uNGAL >200 ng/mL had 84% sensitivity and 86% specificity for graft loss (ROC AUC: 0.89, 95% CI: 0.81-0.97). uNGAL may be useful to predict graft loss after AKI.

Tubular urinary biomarkers do not identify aetiology of acute kidney injury in kidney transplant recipients.

AIM: To evaluate the performance of urinary neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule, interleukin-18 and heat shock protein 72 for differential diagnosis between causes of acute kidney injury in kidney transplant recipients, especially immunological rejection. PATIENTS AND METHODS: We measured these biomarkers in 67 kidney transplant recipients with acute kidney injury according to the RIFLE criteria. RESULTS: There were no statistical differences in biomarkers between kidney transplant recipients with immunological rejection (n = 20), pre-renal causes (n = 20) and other AKI causes (n = 27). Only the uNGAL level relative to urinary creatinine (uNGAL/uCr) for immunological rejection was different in comparison with others (P < 0.001); a cut-off of 59 µg/g of uNGAL/uCr had a sensitivity and specificity of 60% and 58% respectively (area under the curve in receiver-operating characteristic curve, 0.65). The other biomarkers were not useful in differentiating the causes of acute kidney injury. CONCLUSION: The biomarkers tested are not useful in identifying immunological rejection as cause of acute kidney injury in kidney transplant recipients.

Optimizing peritoneal dialysis initiation: A comparative cohort study of catheter placement methods for shortening break-in periods.

INTRODUCTION: Peritoneal dialysis (PD) guidelines recommend a 14-day break-in period after catheter placement, yet this period could be shortened with new insertion techniques. METHODS: We conducted a prospective cohort study to compare percutaneous vs. surgical catheter insertion in a newly established PD program. The break-in period was intentionally shortened to <24 h to start PD almost immediately. RESULTS: We included 223 subjects who underwent percutaneous (34%) or surgical (66%) catheter placement. Compared to the surgical group, the percutaneous group had a higher proportion of early dialysis initiation within 24 h (97% vs. 8%, p < 0.001), similar successful initiation rates (87% vs. 92%, p = 0.34), and shorter lengths of stay (12 [9-18] vs. 18 [14-22] days, p < 0.001). Percutaneous insertion increased the likelihood of successful PD initiation within 24 h (OR 74, 95% CI 31-182), without increasing major complications. CONCLUSION: Percutaneous placement could represent a cost-effective and efficient technique to shorten break-in periods.

Very Low Vitamin D Levels are a Strong Independent Predictor of Mortality in Hospitalized Patients with Severe COVID-19.

BACKGROUND: There is controversy regarding the association between hypovitaminosis D and COVID-19 outcomes. AIM OF THE STUDY: We assessed the association between 25-hydroxyvitamin D levels and COVID-19 outcomes in hospitalized subjects with severe SARS-CoV-2 infection. METHODS: Retrospective cohort study. Serum 25-hydroxyvitamin D levels of subjects with severe COVID-19 pneumonia were measured at hospital admission, between March 17th, 2020, and March 1st, 2021. RESULTS: Out of 2,908 patients, 571 (19.6%) had vitamin D deficiency (defined as a serum 25-hydroxyvitamin D level <12.5 ng/mL [<31.25 nmol/L]), and 1069 (36.7%) had levels between 12.5 ng/mL (31.25 nmol/L) and 20 ng/mL 850 nmol/L). Compared to subjects without vitamin D deficiency, those with 25-hydroxyvitamin D level <12.5 ng/mL had higher rates of in-hospital mortality at 30 d (28.0 vs. 17.3%; p <0.001), global mortality (31.9 vs. 20.8%; p <0.001), mechanical ventilation requirement (23.8 vs. 17.2%; p <0.001), and significantly longer hospital stay (median [interquartile range] of 9 [6-17 d] vs. 7 [5-12 d], p <0.001). In the unadjusted analysis, the risk of in-hospital death was greater for patients with vitamin D deficiency (HR 1.43; 95% CI, 1.20-1.70; p <0.001). After adjusting for confounders, the risk of in-hospital death within 30 d remained significantly greater in patients with vitamin D deficiency (HR 1.46; 95% CI, 1.21-1.76; p <0.001). The risk was reduced but remained significant with 25-hydroxyvitamin D levels between 12.5 ng/mL and 20 ng/mL (HR 1.31; 95% CI 1.10-1.55, p = 0.02). In comparison with other clinical biomarkers, vitamin D deficiency was an independent predictive marker of in-hospital mortality after adjusting for confounders. CONCLUSION: Very low 25-hydroxyvitamin D levels measured at hospital admission were significantly associated with in-hospital mortality and are a useful prognostic biomarker in severe COVID-19 patients.

Anemia, overhydration, and lower muscle strength in hemodialysis patients with protein-energy wasting.

INTRODUCTION: The protein-energy wasting (PEW) syndrome is a common complication in hemodialysis (HD) patients associated to morbidity and mortality. Our objective was to assess the prevalence of PEW and its association with erythropoietin resistance index (ERI) score, body composition by impedance, health-related quality of life, and muscle strength. METHODS: In this cross-sectional, observational, multicenter study, we included data from 191 HD patients from three HD clinics located in Mexico City, Mexico. Clinical and biochemistry variables, body composition, handgrip strength, and the KDQOL-SF36 questionnaire were collected for each patient. FINDINGS: Prevalence of PEW was 22% (n = 41/191), with a higher frequency in those with diabetes mellitus (59% vs. 49%, p = 0.04). Subjects with PEW had lower hemoglobin levels (9.5 + 1.6 g/dl vs. 10.3 + 1.7 g/dl; p = 0.005) and higher ERI scores (19.2 ± 11.2 vs. 15.6 ± 8.2; p = 0.04) compared with the non-PEW group. In analysis of body composition, PEW was associated to higher overhydration status (42.2 vs. 24.9 OH/kg; p = 0.009), higher extracellular water (263 ± 40 vs. 246 ± 32 ml/kg; p = 0.019), lower lean tissue index (12.2 ± 3.2 vs. 14.1 ± 3.7 ml/m2 ; p = 0.021), and lower fat tissue index (9.6 ± 5.7 vs. 12.3 ± 6.2 ml/m2 ; p = 0.043). Handgrip strength was lower in PEW patients (22.5 vs. 28.1 kg; p = 0.002). Finally, no significant differences were observed between groups in quality-of-life assessment. DISCUSSION: In this study, PEW was associated to poor responsiveness to erythropoiesis-stimulating agents, lower muscle strength, and higher overhydration status due to the increase in extracellular water which replaced the loss of tissue. Nevertheless, quality-of-life assessment was not different in patients with PEW compared with those without this complication.

Longitudinal Changes of Serum Creatine Kinase and Acute Kidney Injury among Patients with Severe COVID-19.

Background: Acute kidney injury (AKI) is a common complication of COVID-19. Several etiologies have been identified, including pigment deposition likely associated with myopathic damage. Nevertheless, the relationship between longitudinal creatine-kinase trends and renal outcomes is uncertain. Aim: To correlate longitudinal changes in serum creatine-kinase levels with hospital-acquired AKI (beyond 48 h of hospital admission) in severe COVID-19 patients. Methods: This is a retrospective cohort study, and creatine-kinase levels were assessed over time in 1551 hospitalized patients with normal renal function at the time of hospital admission. Results: In subjects who developed hospital-acquired AKI (n = 126, 8.1%), the serum creatine-kinase concentration before AKI onset was not different when compared to patients without AKI (slope of log creatine-kinase/day = -0.09 [95% CI -0.17 to +0.19] vs. +0.03 [95% CI -0.1 to +0.1]). After AKI diagnosis, serum creatine-kinase levels showed a significantly ascendent slope (slope of log creatine-kinase/day after AKI diagnosis = +0.14; 95% CI + 0.05 to +0.3). The AKI evolution was the main factor associated with the creatine-kinase trend. Subjects with persistent AKI (n = 40, 32%) had rising creatine-kinase levels during hospitalization (slope of log creatine-kinase/day = +0.30 95% CI + 0.19 to +0.51). A rising creatine-kinase trend (n = 114, 8%) was associated with a 1.89-fold higher risk of in-hospital death (95% CI 1.14 to 3.16). Nevertheless, this association disappeared after adjusting AKI evolution and LDH baseline levels. Conclusion: In severe COVID-19 patients, a slight increase in creatine-kinase levels was observed after AKI occurrence but not before. Our results show that, at least for the appearance of hospital-acquired AKI, the CK rise does not meet the temporality criterion of causality regarding the occurrence of AKI. Rising creatine-kinase trends were associated with a higher risk of mortality, but this association was modified by AKI evolution and inflammation. There is a limited efficiency for AKI prognosis in the serial follow-up of CK levels in severe COVID-19 patients with normal renal function.

A Nonseminomatous Germ Cell Tumor Presenting as a Mixed Cryoglobulinemic Vasculitis.

Background: Mixed cryoglobulinemia syndrome (MCS) is a rare entity with a variety of causes but has not been associated with testicular germ cell tumors. We present here a case of a patient with a nonseminomatous germ cell tumor (NSGCT) presenting as a type III mixed cryoglobulinemic vasculitis. Case Presentation. A 58-year-old male exhibited typical clinical features of vasculitis, including weakness, fatigue, palpable purpura, multiple mononeuropathy, and a low C4 level. An MCS diagnosis was confirmed by the presence of cryoglobulins (6%) with polyclonal IgM and IgG components and biopsy proven leukocytoclastic vasculitis. Concomitantly, a stage IIIC (TxNxM1bS1) germ tumor with marked elevation of serum beta-human chorionic gonadotropin (2764 mUI/mL) was diagnosed. An aggressive treatment was needed, including methylprednisolone pulses, plasmapheresis, rituximab, followed by orchiectomy, and chemotherapy (bleomycin/etoposide/cisplatin). After tumor resection and treatment, cryoglobulins decrease to 0%, suggesting a paraneoplastic origin of the vasculitis. Conclusion: To the best of our knowledge, this is the first case of MCS possibly attributable to a NSGCT. This case further elaborates on the presentation of mixed cryoglobulinemia vasculitis and adds to the published literature on the topic.

Validation of an equation for free calcium estimation: accuracy improves after adjustment for phosphate and CO2.

PURPOSE: Free calcium is the gold standard for diagnosis of calcium disorders, although calcium assessment is routinely performed by albumin-adjusted calcium. Our objective was to develop a novel-specific correction equation for free calcium employing serum total calcium and other analytes. METHODS: Retrospective single-center cohort study. A new equation for free calcium assessment was formulated from data of hospitalized patients (n = 3481, measurements = 7157) and tested in a validation cohort (n = 3218, measurements = 6911). All measurements were performed simultaneously from the same blood draw. RESULTS: Total CO2 and phosphate, in addition to albumin, were the principal factors associated to calcium misdiagnosis. A novel laboratory-specific prediction equation was developed: free calcium (mmol/L) = 0.541 + (total calcium [mmol/L] *0.441) - (serum albumin [g/L] *0.0067) - (serum phosphate [mmol/L] *0.0425) - (CO2 [mmol/L] *0.003). This new equation substantially improved adjusted R2 to 0.67 (95% CI 0.78-0.82, p < 0.001; Kendall's c-tau: 0.28, p < 0.001). Bland-Altman plots of estimated free calcium and free calcium showed a mean difference of - 0.0006 mmol/L (LOA + 0.126 to - 0.124). In validation cohort, the AUC-ROC curves for hypercalcemia and hypocalcemia diagnosis deploying the new equation were 0.88 (95% CI 0.86-0.89, p < 0.001) and 0.98 (95% CI 0.97-99, p < 0.001), respectively, which were superior to historical formulas for calcium. In univariate models, eGFR was associated with Ca-status misdiagnosis, yet this association disappeared when analysis was adjusted to phosphate and CO2. CONCLUSIONS: The novel equation proposed for prediction of free calcium could be useful when free calcium is not available. The conventional formulas misclassify many patients, in particular when phosphate or bicarbonate disturbances are present.

Cholecalciferol supplementation increases FGF23 in peritoneal dialysis patients with hypovitaminosis D: a randomized clinical trial.

BACKGROUND: Vitamin D deficiency is common in peritoneal dialysis (PD) patients, so its supplementation has been advocated as potentially beneficial. METHODS: Double-blind, placebo-controlled, randomized clinical trial. Subjects on PD treated with high calcium peritoneal dialysate (Ca 3.5 mEq/l) and serum levels of 25-hydroxi vitamin D (25D) < 20 ng/ml were randomized to receive cholecalciferol (4800 IU/daily) or placebo for 16 weeks. The outcome measures were the effects on the osteogenic biomarkers osteoprotegerin (primary endpoint), intact fibroblast growth factor-23 (iFGF23), osteocalcin, osteopontin, iPTH, 1,25-dyhydroxivitamin D (1,25D), and interleukin-6. RESULTS: Fifty-eight subjects were randomly assigned. Baseline characteristics were similar in both groups. Cholecalciferol supplemented subjects had a significant increase in serum 25D (from 11.4 ± 5.0 to 28.3 ± 10.3 ng/ml), 1,25D and iFGF23 compared with placebo group. iFGF23 levels increased an average of 10,875 pg/ml per month (95% CI 11,778-88,414) in the cholecalciferol group and was unchanged in the placebo group (2829 pg/ml, 95% CI - 2181 to 14,972). Extremely high iFGF23 levels (> 30,000 pg/ml) were observed in 74% of subjects receiving cholecalciferol although iFGF23 returned to baseline values after 32 weeks of withdrawal. The observed changes in iFGF23 correlated with 1,25D levels and were not modified by other variables. No difference was observed between groups in osteoprotegerin or other osteogenic biomarkers levels. CONCLUSIONS: Cholecalciferol supplementation increases serum 25D levels in subjects on PD exposed to high calcium dialysate, yet it induces an exponential increase of iFGF23 in most patients, which disappear after withdrawal of supplementation and may be a major concern for this maneuver.

Treatment of Hyperuricemia in Chronic Kidney Disease.

Hyperuricemia may be a major contributor to the development or progression of chronic kidney disease (CKD). Although there is no clear cutoff uric acid (UA) value associated to the risk for kidney damage, it appears to be an increased risk as UA rises. Lifestyle interventions such as exercise, weight reduction, low consumption of purine-rich meat, or avoiding high fructose intake are recommended for all hyperuricemic patients. Lowering urate drugs such as allopurinol or febuxostat may be an option as a renoprotective agent; yet, randomized clinical trials evaluating the safety and efficacy of these drugs are limited to a small number of single-center studies. Several ongoing clinical trials aim to evaluate the safety and efficacy of these drugs. As of today, there is insufficient evidence to recommend the widespread use of UA-lowering therapy to prevent or slow down the progression of CKD. The purpose of this review is to summarize the evidence and future perspectives about the treatment of hyperuricemia in the prevention and progression of CKD.

Chronic kidney disease after acute kidney injury associated with intravenous colistin use in survivors of severe infections: A comparative cohort study.

PURPOSE: The use of colistin for multi-drug resistant (MDR) infections has led to an increase of colistin-associated acute kidney injury (AKI). Nevertheless, information on long-term renal prognosis is scarce. We aimed to determine the predictors of chronic kidney disease (CKD) in survivors of MDR-infections with colistin-associated AKI. METHODS: A retrospective cohort of patients with colistin-associated AKI was compared with controls (survivors of severe infections who developed AKI matched by age, sex, diabetes, vancomycin exposure, and baseline kidney function). The primary outcome was the development of CKD after 6months of follow-up. RESULTS: From 2011 to 2015, 122 patients with MDR infections received colistin. Among 72 survivors, 29 (40%) had colistin-associated AKI. After 6months, 22 of them (75%) progressed to CKD (G3 in 21/22) compared with 16 (27%) in 58 controls (P<0.001). Independent predictors of progression to CKD were colistin use [odds ratio (OR): 8.86; 95% CI: 2.8-27.8] and age (OR: 1.04, 95% CI: 1.01-1.07). In patients exposed to colistin, a total dose of colistin >5g was an independent predictor of progression to CKD (OR: 14.1, 95% CI: 2.6-75.7). CONCLUSION: Colistin-associated AKI had a substantial risk for the latter development CKD, and consequently, these patients should be tightly monitored.