Role of antineutrophil cytoplasmic antibodies and glomerular basement membrane antibodies in the diagnosis and monitoring of systemic vasculitides.

Systemic vasculitis, although rare, is often diagnosed late and long after the onset of symptoms. The small vessel vasculitides are recognized clinically by their multisystem presentation, markers of inflammation and evidence for an acute glomerulonephritis (GN), with the most apparent organ involved directing referral to secondary care. Routine laboratory tests are usually non-specific in systemic vasculitis but the use of anti-neutrophil cytoplasmic antibodies (ANCAs) and glomerular basement membrane (GBM) antibodies can aid diagnosis, treatment and monitoring decisions. These antibodies are detected and quantified by indirect immunofluorescence (IIF) and antigen-specific enzyme-linked immunosorbent assay (ELISA), usually in combination for ANCA, and ELISA systems (or direct IIF on kidney biopsy) for GBM antibodies. The presence or absence of ANCA does not confirm or exclude the diagnosis of systemic vasculitis but negative and positive predictive values will be strongly influenced by clinical presentation. Various large studies have been unable to conclude that following serial ANCA titres has great clinical utility in each case but each patient must be considered on its own merits; for example the reappearance of ANCA in a patient who was rendered ANCA negative following treatment is more likely to indicate relapse. The adoption of consensus guidelines that direct testing towards patients with rapidly progressive GN, pulmonary haemorrhage, persistent and destructive ear, nose and upper airways problems, such as subglottic tracheal stenosis, a retro-orbital mass and cutaneous vasculitis with systemic features or peripheral neuropathy, will greatly increase the clinical utility and positive predictive value of these tests.

Continuous ambulatory peritoneal dialysis patients are unable to increase dietary intake to recommended levels.

OBJECTIVE: This study's objective was to determine whether offering dietary advice was effective in supporting patients in adjusting energy intake. DESIGN: We performed a prospective, randomized, controlled trial of dietary intervention involving 59 patients on continuous ambulatory peritoneal dialysis over a 4-month follow-up period. SETTING: The study involved outpatients on home-based renal replacement therapy. PARTICIPANTS: All participants were adult patients on continuous ambulatory peritoneal dialysis. All eligible patients were invited to take part. Subjects were randomized into two groups: control and intervention. Those with diabetes mellitus, malabsorption, malignancy, or eating disorders were excluded. INTERVENTION: Baseline measurements to assess current dietary intake and nutritional status were performed in all subjects. Measurements included a 5-day food diary, subjective global assessment (SGA), anthropometry, and serum biochemistry. After analysis of the food diaries, the participants in the control group were given follow-up dietary advice that would enable them to match intake with current dietary recommendations for this group of 1.2 g of protein per kilogram of ideal body weight, 25 cal/kg ideal body weight. Participants in the intervention group were given follow-up dietary advice that would encourage them to match energy intake with an estimate of total energy expenditure based on their calculated basal metabolic rate and physical activity level as designated using information from SGA, with a significantly lower protein intake of 0.8 to 1.0 g/kg ideal body weight and an emphasis on calories from carbohydrate and fat. Both groups completed further 5-day food diaries at 2 and 4 months to assess their ability to make the recommended changes. SGA, anthropometry, and biochemistry were all remeasured at the end of the study period. MAIN OUTCOME MEASURE: Differences in energy and protein intakes between and within the two groups from baseline to 4 months were assessed. RESULTS: Protein and energy intakes did not change during 4 months in either group, and there was no significant difference in intake between the two groups. In the control group (n = 27), 18 subjects (69%) matched their reported dietary energy intake to the recommended intake. In the intervention group (n = 28), 17 subjects (63%) matched their reported dietary intake to their estimated total energy expenditure. In the control group (n = 27), 8 subjects (28%) achieved the protein intake recommended to them of 1.2 g/kg. In the intervention group (n = 28), 23 subjects (85%) achieved the protein intake recommended to them of greater than 0.8 g/kg. CONCLUSION: Patients not meeting their dietary prescription did not adjust their intake to match the recommended advice they had been given from a dietitian. Food diary analysis showed that subjects ate less than the recommended intakes for energy and protein. This inability to change suggests that subjects may be eating to the limit of their appetite. SGA sections concerning appetite, body weight, body mass index, and estimates of energy expenditure support the view that energy intake matches requirements.