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Objective: Although there has been contrasting evidence for a causative role of parathyroid hormone (PTH) in sleep disorders in patients on maintenance hemodialysis, a recent study disclosed the possibility that this role might exist at least in patients requiring parathyroidectomy because of failure of medical therapy. The present study was devised to assess a possible difference in sleep disorders of patients on hemodialysis needing parathyroidectomy and those in whom medical therapy controlled hyperparathyroidism. Design and Patients: To this end, a group of 22 patients requiring parathyroidectomy were studied by means of a sleep questionnaire, along with a group of 44 patients matched for age, gender, body weight, and duration of dialytic treatment. Results: Patients requiring parathyroidectomy slept fewer hours (P < .001), had a higher prevalence of sleep disorders (P < .001), and were more often insomniac (P < .001). Conclusions: This study indicates that patients on hemodialysis requiring parathyroidectomy for intractable hyperparathyroidism comprise a good model for investigating the causative role of PTH on disordered sleep, and that these patients have very poor sleep. These data support recent findings on the prevalence of sleep disorders in dialyzed patients with insuppressible hyperparathyroidism. © 2008 National Kidney Foundation, Inc.

Objective Sleep disorders are very common in adult and children on maintenance hemodialysis and are not cured by renal transplantation. Setting/Design Studies in our laboratory of patients with a mean plasma creatinine concentration of 2 mg/dL, studied within 2 months of chronic kidney disease (CKD) diagnosis, have detected a high prevalence of sleep disorders that could not be explained by using the factors prevalent in hemodialysis patients. Main Outcome Measures To understand if the intrusiveness of the disease is a cause for the high prevalence of sleep disorders in early CKD, we have assessed, by means of a questionnaire, sleep disorders within 1 month from the diagnosis of renal dysfunction. Results A total of 100 CKD patients with a mean estimated creatinine clearance of 59.1 ± 26.7 mL/min were studied. The prevalence of sleep disorders was 89%. Conclusion We believe this high prevalence might represent the effects of disease's intrusiveness and difficulty in coping with the disease.

Possible mechanisms of homocysteine toxicity. Hyperhomocysteinemia is a risk factor for cardiovascular disease in the general population. In chronic renal failure (CRF), plasma homocysteine levels rise when the glomerular filtration rate (GFR) is reduced 50%, and in uremia the majority of patients are hyperhomocysteinemic. The purpose of this study was to review possible mechanisms of homocysteine toxicity. Homocysteine, a sulfur amino acid found in blood in micromolar concentrations, can have toxic effects through a handful of general possible mechanisms. These mechanisms include oxidative stress (through the production of reactive oxygen species), binding to nitric oxide, production of homocysteinylated/acylated proteins, and accumulation of its precursor, S-adenosyl-homocysteine, a potent inhibitor of transmethylation reactions. Methyltransferase inhibition actually occurs in CRF and in uremia, and can have several functional consequences.

Hyperhomocysteinemia is an independent cardiovascular risk factor that possibly accounts for about one of 5 cardiovascular deaths. It is conceivable that the importance of hyperhomocysteinemia will increase when other risk factors, such as hypertension or hypercholesterolemia, will become less prevalent in the general population. In chronic renal failure (CRF), high plasma homocysteine levels are a common finding and in uremia almost the rule. However, a small subset of patients remains normohomocysteinemic. The cause of hyperhomocysteinemia in CRF, whether it lies in an impaired renal or extrarenal metabolism or through uremic retention toxins, is still under intensive scrutiny. As for the consequences of high homocysteine levels in the general population and in patients with CRF, these are many-fold and linked to the mechanism of homocysteine toxic action. In fact, homocysteine can be harmful to cells because (1) it evokes oxidative stress (through the production of reactive oxygen species), (2) binds to nitric oxide, (3) produces homocysteinylated proteins, or (4) leads to the accumulation of its precursor, S-adenosylhomocysteine, a potent inhibitor of biological transmethylations. Macromolecule hypomethylation is a common feature in CRF and uremia with possible functional consequences. Nutritional or pharmacologic interventions have been proposed in the treatment of hyperhomocysteinemia, while the results of large clinical trials designed to assess if lowering homocysteine levels is effective in reducing cardiovascular risk, are pending. © 2003 by the National Kidney Foundation, Inc.