Association between circulating fibroblast growth factor 21 and mortality in end-stage renal disease.

Fibroblast growth factor 21 (FGF21) is an endocrine factor that regulates glucose and lipid metabolism. Circulating FGF21 predicts cardiovascular events and mortality in type 2 diabetes mellitus, including early-stage chronic kidney disease, but its impact on clinical outcomes in end-stage renal disease (ESRD) patients remains unclear. This study enrolled 90 ESRD patients receiving chronic hemodialysis who were categorized into low- and high-FGF21 groups by the median value. We investigated the association between circulating FGF21 levels and the cardiovascular event and mortality during a median follow-up period of 64 months. A Kaplan-Meier analysis showed that the mortality rate was significantly higher in the high-FGF21 group than in the low-FGF21 group (28.3% vs. 9.1%, log-rank, P = 0.034), while the rate of cardiovascular events did not significantly differ between the two groups (30.4% vs. 22.7%, log-rank, P = 0.312). In multivariable Cox models adjusted a high FGF21 level was an independent predictor of all-cause mortality (hazard ratio: 3.98; 95% confidence interval: 1.39-14.27, P = 0.009). Higher circulating FGF21 levels were associated with a high mortality rate, but not cardiovascular events in patient with ESRD, suggesting that circulating FGF21 levels serve as a predictive marker for mortality in these subjects.

Association between Serum Soluble Klotho Levels and Mortality in Chronic Hemodialysis Patients.

Klotho is a single-pass transmembrane protein predominantly expressed in the kidney. The extracellular domain of Klotho is subject to ectodomain shedding and is released into the circulation as a soluble form. Soluble Klotho is also generated from alternative splicing of the Klotho gene. In mice, defects in Klotho expression lead to complex phenotypes resembling those observed in dialysis patients. However, the relationship between the level of serum soluble Klotho and overall survival in hemodialysis patients, who exhibit a state of Klotho deficiency, remains to be delineated. Here we prospectively followed a cohort of 63 patients with a mean duration of chronic hemodialysis of 6.7 ± 5.4 years for a median of 65 months. Serum soluble Klotho was detectable in all patients (median 371 pg/mL, interquartile range 309-449). Patients with serum soluble Klotho levels below the lower quartile (<309 pg/mL) had significantly higher cardiovascular and all-cause mortality rates. Furthermore, the higher all-cause mortality persisted even after adjustment for confounders (hazard ratio 4.14, confidence interval 1.29-13.48). We conclude that there may be a threshold for the serum soluble Klotho level associated with a higher risk of mortality.

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

Obstructive sleep apnea (OSA) is common in patients with renal disease, and an association between OSA and proteinuria has been proposed. However, the effect on proteinuria of OSA treatment with continuous positive airway pressure (CPAP) is unknown. We experienced a case of severe OSA, where proteinuria was clearly improved after CPAP initiation without any changes of medication or body weight. The remarkable reduction of repetitive apnea and hypopnea by CPAP might ameliorate proteinuria by lessening renal hypoxia and sympathetic nerve activation. This case suggests that CPAP is a promising option for OSA with proteinuria.

Sleep-disordered breathing predicts cardiovascular events and mortality in hemodialysis patients.

BACKGROUND: Sleep-disordered breathing (SDB), characterized by repetitive apnea and hypopnea during sleep, is a risk factor for cardiovascular disease. However, the links between SDB and cardiovascular events in hemodialysis (HD) patients have not been clearly evaluated. METHODS: We followed the clinical outcome of 94 HD patients, who underwent overnight pulse oximetry on dialysis day. The SDB group was defined as 3% oxygen desaturation index (ODI) over five events per hour, and the others were the normal group. The primary outcome was cardiovascular events and death. We used Kaplan-Meier curve and Cox proportional hazard model for survival analyses. RESULTS: Forty-four patients (46.8%) were classified into the SDB group. Body mass index, diabetes mellitus, 3% ODI and Epworth sleepiness scale were significantly higher, and duration of dialysis, Kt/V, normalized protein catabolism rate and hemoglobin were lower in the SDB group than in the normal group. During a median 55 months of follow-up, Kaplan-Meier analysis revealed that the SDB group had a significantly higher rate of cardiovascular events and all-cause mortality than the normal group. Age, cardiothoracic ratio, serum albumin and 3% ODI were predictors of cardiovascular events and all-cause mortality at univariate Cox regression analysis. In the adjusted analysis, SDB is an independent predictor of increased cardiovascular events (hazard ratio 3.10; 95% confidence interval (CI), 1.35-7.12; P = 0.008) and all-cause mortality (hazard ratio 2.81; 95% CI, 1.07-7.41; P = 0.037). CONCLUSIONS: SDB is an independent risk factor for cardiovascular events and mortality in HD patients. Effective and earlier treatment for these patients is needed to improve clinical outcome.

Hyponatremic seizure associated with acute respiratory infection.

A 66-year-old woman was admitted to our hospital because of vomiting and appetite loss. For the 2 days prior to admission, she had a cold, which had developed into acute viral bronchitis on admission. Because laboratory data on admission showed hyponatremia, intravenous infusion of Ringer's lactate solution was started. However, generalized seizures appeared, and she developed a coma on the day of admission. Her plasma antidiuretic hormone (ADH) level was high in the context of a low serum osmolality on the second hospital day. The infusion rate was increased, and the patient's consciousness level returned to normal. However, her normalized serum Na level declined again as she drank much water to reduce throat discomfort. As the throat discomfort caused by the throat inflammation improved with azulene gargling, her water intake was reduced, and the serum Na concentration returned to normal. Thus, polydipsia caused by a throat inflammation partially contributed to hyponatremia in this patient. We note that increased ADH secretion has been reported in adults with acute respiratory infection. Therefore, we concluded that polydipsia caused by the throat inflammation, plus increased ADH secretion, resulted in hyponatremia in this patient. We should pay attention to the behavior of drinking extra fluid in patients with acute respiratory infections.

[Additive antiproteinuric effect of angiotensin II receptor antagonist and angiotensin-converting enzyme inhibitor in patients with chronic glomerulonephritis].

Angiotensin II type-1 receptor blocker (ARB) and angiotensin-converting enzyme inhibitor (ACEI) have been thought to be effective for reducing proteinuria in patients with chronic glomerulonephritis. Recently, an additive effect of these two types of angiotensin blockers has been reported in patients with IgA nephropathy, but the mechanism responsible for the effect has not yet been determined. In this study, we examined additive effect of these two drugs in chronic glomerulonephritis patients. Ten patients with biopsy-proven primary glomerulonephritis (eight IgA nephropathy patients, two membranous nephropathy patients), non-nephrotic proteinuria (protein, 0.5 to 3.5 g/day) received candesartan cilexetil (2 or 4 mg) for 8 weeks. After the 8 weeks, a combination of perindopril erbumine (1 or 2 mg) and candesartan cilexetil was administered to the patients. Perindopril was stopped after the 8-week administration of the two drugs. Candesartan alone reduced proteinuria by 13%. Combination of these two drugs induced a more remarkable reduction of proteinuria (48%; p < 0.05 vs other periods). The decrease in mean blood pressure by the combination therapy was significantly correlated with the decrease in proteinuria. The combination of drugs also reduced the amount of urinary type-IV collagen excretion. An additive effect of ACEI and ARB on proteinuria and urinary type-IV collagen excretion was recognized in patients with chronic glomerulonephritis.