The implications of a diagnosis of lupus are considerable, and we propose that the term 'seronegative lupus nephritis' is unhelpful, and should be avoided when there is diagnostic uncertainty. The term C1q nephropathy should be preferred when these histological features are seen in the absence of overt lupus, when C1q deposition is dominant and when tubuloreticular bodies are absent. The clinical course in the cases reported here does not support the use of immunosuppressive therapy in C1q nephropathy.

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Introduction Malnutrition is common in patients with acute kidney injury (AKI), particularly in those requiring renal replacement therapy (RRT). Use of RRT removes metabolic waste products and toxins, but it will inevitably also remove useful molecules such as micronutrients, which might aggravate malnutrition. The RRT modalities vary in mechanism of solute removal; for example, intermittent hemodialysis (IHD) uses diffusion, continuous veno-venous hemofiltration (CVVH) uses convection, and sustained low-efficiency diafiltration (SLEDf) uses a combination of these. Methods We assessed micronutrient and amino acid losses in 3 different RRT modalities in patients with AKI (IHD, n = 27; SLEDf, n = 12; CVVH, n = 21) after correction for dialysis dose and plasma concentrations. Results Total losses were affected by modality; generally CVVH >> SLEDf > IHD (e.g., amino acid loss was 18.69 ± 3.04, 8.21 ± 4.07, and 5.13 ± 3.1 g, respectively; P < 0.001). Loss of specific trace elements (e.g., copper and zinc) during RRT was marked, with considerable heterogeneity between RRT types (e.g., +849 and +2325 μg/l lost during SLEDf vs. IHD, respectively), whereas effluent losses of copper and zinc decreased during CVVH (effect size relative to IHD, −3167 and −1442 μg/l, respectively). B vitamins were undetectable in effluent, but experimental modeling estimated 40% to 60% loss within the first 15 minutes of RRT. Conclusion Micronutrient and amino acid losses are marked during RRT in patients with AKI, with variation between RRT modalities and micronutrients.

Background: Acute kidney injury (AKI) is commonly defined using the KDIGO system, which includes criteria based on reduced urine output (UO). There is no consensus on whether UO should be measured using consecutive hourly readings or mean output. This makes KDIGO UO definition and staging of AKI vulnerable to inconsistency which has implications both for research and clinical practice. The objective of this study was to investigate whether the way in which UO is defined affects incidence and staging of AKI. Methods: We conducted a retrospective analysis of two single centre observational studies investigating (i) patients undergoing cardiac surgery and (ii) patients admitted to general intensive care units (ICU). AKI was identified using KDIGO serum creatinine (SCr) criteria and two methods of UO (UO cons : UO meeting KDIGO criteria in each consecutive hour; UO mean : mean hourly UO meeting KDIGO criteria). Results: Data from 151 CICU and 150 ICU admissions were analysed. Incidence of AKI using SCr alone was 23.8% in CICU and 32% in ICU. Incidence increased in both groups when UO was considered, with inclusion of UO mean more than doubling reported incidence of AKI (CICU: UO cons 39.7%, UO mean 72.8%; ICU: UO cons 51.3%, UO mean 69.3%). In both groups UO cons led to a larger increase in KDIGO stage 1 but UO mean increased the incidence of KDIGO stage 2. Conclusions: We demonstrate a serious lack of clarity in the internationally accepted AKI definition leading to significant variability in reporting of AKI incidence.