Klotho gene mutation leads to a syndrome strangely resembling chronic kidney disease patients undergoing dialysis with multiple accelerated age-related disorders, including hypoactivity, sterility, skin thinning, muscle atrophy, osteoporosis, vascular calcifications, soft-tissue calcifications, defective hearing, thymus atrophy, pulmonary emphysema, ataxia, and abnormalities of the pituitary gland, as well as hypoglycemia, hyperphosphatemia, and paradoxically high-plasma calcitriol levels. Conversely, mice overexpressing klotho show an extended existence and a slow aging process through a mechanism that may involve the induction of a state of insulin and oxidant stress resistance. Two molecules are produced by the klotho gene, a membrane bound form and a circulating form. However, their precise biological roles and molecular functions have been only partly deciphered. Klotho can act as a circulating factor or hormone, which binds to a not yet identified high-affinity receptor and inhibits the intracellular insulin/insulin-like growth factor-1 (IGF-1) signaling cascade; klotho can function as a novel β-glucuronidase, which deglycosylates steroid β-glucuronides and the calcium channel transient receptor potential vallinoid-5 (TRPV5); as a cofactor essential for the stimulation of fibroblast growth factor (FGF) receptor by FGF23. The two last functions have propelled klotho to the group of key factors regulating mineral and vitamin D metabolism, and have also stimulated the interest of the nephrology community. The purpose of this review is to provide a nephrology-oriented overview of klotho and its potential implications in normal and altered renal function states.

The use and effectiveness of cinacalcet in 'real-world' clinical practice was investigated in a pan-European observational study in dialysis patients with secondary hyperparathyroidism (SHPT) of varying severity. Adult patients with chronic kidney disease on dialysis who had initiated cinacalcet treatment were enrolled. Data were collected 6 months before initiating cinacalcet, at baseline (initiation of cinacalcet) and up to 12 months after cinacalcet initiation. A total of 1865 patients [mean (SD) age 58 (15) years] were enrolled from 187 sites in 12 countries. Most patients had a dialysis vintage of > or =1 year (1-5 years, n = 833; >5 years, n = 748 versus <1 year, n = 265). The patients generally had severely uncontrolled intact parathyroid hormone (iPTH) serum levels (median 721 pg/ml) and elevated phosphorus (median 5.9 mg/dl) and calcium (median 9.6 mg/dl) at baseline, despite being prescribed conventional therapies. The proportions of patients achieving the recommended [NKF-K/DOQI(TM) (KDOQI(TM))] targets increased from baseline [4%, 39%, 40% and 46% for iPTH, phosphorus, calcium and calcium-phosphorus product (Ca x P), respectively] to Month 12 (28%, 48%, 51% and 68%, respectively). At Month 12, 18% of patients had achieved the combined target for iPTH + Ca x P compared with 2% at baseline. Most patients (65%) received <60 mg/day cinacalcet at Month 12. Vitamin D sterol use remained fairly stable throughout the study. There was a 13% decrease in prescribed sevelamer; use of calcium-based phosphate binders increased by 5.6%. There was no unexpected safety or tolerability concerns. This analysis of current European clinical practice shows that-consistent with findings from randomized controlled trials and retrospective observational studies-cinacalcet improves attainment of KDOQI bone metabolism targets in dialysis patients with various stages of SHPT.

Diabetic kidney disease is one of the most relevant complications in diabetes mellitus patients, which constitutes the main cause of end-stage renal disease in the western world. Delaying the progression of this pathology requires new strategies that, in addition to the control of traditional risk factors (glycemia and blood pressure), specifically target the primary pathogenic mechanisms. Nowadays, inflammation is recognized as a critical novel pathogenic factor in the development and progression of renal injury in diabetes mellitus. Pentoxifylline is a nonspecific phosphodiesterase inhibitor with rheologic properties clinically used for more than 30 years in the treatment of peripheral vascular disease. In addition, this compound also exerts anti-inflammatory actions. In the context of diabetic kidney disease, pentoxifylline has shown significant antiproteinuric effects and a delay in the loss of estimated glomerular filtration rate, although at the present time there is no definitive evidence regarding renal outcomes. Moreover, recent studies have reported that this drug can be associated with a positive impact on new factors related to kidney health, such as Klotho. The use of pentoxifylline as renoprotective therapy for patients with diabetic kidney disease represents a new example of drug repositioning.

The ADVANCE study assessed the progression of vascular and cardiac valve calcification in 360 hemodialysis patients with secondary hyperparathyroidism (sHPT) assigned randomly to treatment either with cinacalcet plus low-dose vitamin D (≤6 µg/week of intravenous paricalcitol equivalent) or with varying doses of vitamin D alone for 52 weeks. The primary efficacy endpoint was progression of coronary artery calcification (CAC). In this post-hoc analysis, we compared CAC progression among 70 protocol-adherent subjects given cinacalcet and low doses of vitamin D (CPA) as specified in the study protocol and 120 control subjects given vitamin D sterols. Baseline patient characteristics did not differ between CPA and control subjects. The mean (standard error of the mean, SEM) doses of vitamin D at week 2 were 4.7 (0.3) and 12.8 (1.0) µg/week in CPA and control subjects, respectively, and the corresponding mean cumulative doses of vitamin D over 52 weeks in each group were 225 (22) and 671 (47) µg. The median change in Agatston CAC score after 52 weeks was less in CPA subjects than in controls (17.8% versus 31.3%, P = 0.02). The median increase in calcification scores in the aortic valve also was less in CPA subjects than in controls (6.0% versus 51.5% P = 0.02). Reductions in serum parathyroid hormone, calcium and phosphorus levels were significantly greater in CPA subjects than in controls (P < 0.05). The progression of cardiovascular calcification was attenuated among cinacalcet-treated subjects with sHPT given low doses of vitamin D per protocol compared with control subjects in whom sHPT was treated with higher doses of vitamin D sterols alone.