Proteinuria in obstructive sleep apnea

Abstract

Letters to the Editor 1551 genesis, where ANCA are much but not enough; and (2)Between July and September of 2001, we performed an observational prospective study of all the patients the role of cytokines [1].referred to our Sleep Unit who underwent a polysom-Two years ago, we conducted an observational study on nography because of suspected obstructive sleep apnea. 14 first diagnosed, previously untreated, biopsy-proved Patients with unstable chronic heart failure, diabetes or AARV patients referred to our Renal Unit, testing a known nephropathy were excluded. set of markers [erythrocyte sedimentation rate (ESR),In all 45 patients we determined, in 12 hours' urine C-reactive protein (CRP), leukocyte count, fibrinogen, analysis, proteinuria by Miltistix (Bayer Diagnostics, ferritin, C3 and C4 factors, IgG, ANCA title and anti-UK) and in 30 of them microalbuminuria was detergens] for sensitivity, specifity, and prognostic value. The mined by turbidimetric method (Synchron CX, Beckcontrol group included 14 cases with "vasculitis lookman Coulter, Brea, CA, USA) to assess glomerular proalike" diseases (mainly primary glomerulonephritides) teinuria with more sensibility. An apnea hypopnea index with similar age and renal impairment.(AHI) higher than 5 was diagnostic of obstructive sleep As expected, ANCA title and antigens and all other apnea. data did not show any relation with histology, severity Most patients were male (85%), median values were of renal failure, lung involvement, or outcome. Interestage, 54 years (26 to 74 years); PaO 2 , 75 mm Hg (50 to ingly, however, no cases with high serum IgG needed di-90 mm Hg); AHI, 33 (8 to 107); and body mass index alysis (five out of five patients), but six of nine with nor-(BMI), 31 kg/m 2 (22 to 47 kg/m 2 ). mal IgG did so (P ϭ 0.01, Fisher's Exact Test). We thoughtWe did not find any patient with microalbuminuria that these five had a more recent stage of vasculitis, when higher than reference limit (0-20 mlg/L). Two patients therapy can be more effective. Professor Savage's hyhad a Multistix test with 1ϩ, proteinuria, but significant pothesis of a shift from humoral (antibody-dependent) to microalbuminuria was not found, perhaps based on the cellular (T-cell-dependent) damage in vasculitis course is observer's bias of the Multistix method. in agreement with our findings.In our study we did not find any significant proteinuria Apart of ANCA, only CRP and ferritin had diagnostic due to primary renal disease, likely because of the samvalue. The former was more sensitive (100% vs. 71%), ple's size. the latter more specific (93% vs. 43%). Ferritin specif-We did not find proteinuria in the obese population, icity was a surprise. Was it related to a bias or to some even in those with morbid obesity. Neither did we find mechanism of disease (oxidative injury, tumor necrosis proteinuria in hypoxic patients or in patients with high factor (TNF) action)? Professor Savage's lesson on the blood pressure. role of TNF in AARV could be the answer to our doubt.The results of previous...

Effect of continuous positive airway pressure on proteinuria in obstructive sleep apnea

“…We report a severe OSA patient, whose proteinuria clearly decreased after CPAP treatment without any changes of medication or body weight. Previous studies have reported that OSA is associated with increased proteinuria [ 4 – 6 ], but other reports have denied this [ 11 – 13 ]. Therefore, the association between OSA and proteinuria has been controversial.…”

“…Second, our case alone is not sufficient to prove the effect of CPAP on proteinuria. Several cross-sectional studies showed that significant proteinuria is uncommon in patients with OSA [ 11 , 13 ]. On the other hand, a recent prospective interventional study of 121 OSA patients demonstrated that albuminuria, which reflects generalized endothelial dysfunction, decreased after CPAP treatment [ 29 ].…”