Dialysis or transplantation: fitting the treatment to the patient.

Early referral of the patient with chronic renal failure will give the nephrologist time to fit the treatment to the patient. Planning for dialysis and transplantation should be undertaken concurrently. If the patient is not of advanced age and is not afflicted with severe comorbid illness, renal transplantation is the preferred form of renal replacement therapy. Living donor transplantation is preferred to cadaveric transplantation. For the patient who awaits or who cannot undergo transplantation, either peritoneal dialysis or hemodialysis may be chosen. Although the mortality rate for peritoneal dialysis appears to be higher than that for hemodialysis, especially among elderly diabetic patients, peritoneal dialysis remains an acceptable therapy for the highly motivated patient. In the United States, the mortality rate for chronic dialysis patients is high. We expect mortality rates for both peritoneal dialysis and hemodialysis to fall, however, as we strive to achieve optimal solute clearance and to more effectively treat comorbid illness.

Patient mortality in chronic dialysis: comparisons between hemodialysis and peritoneal dialysis.

Patients with approaching end-stage renal disease often must choose between hemodialysis or peritoneal dialysis as the initial form of renal replacement therapy. Should nephrologists recommend one form of dialysis as superior to the other? This review focuses on studies that compared patient mortality for these two dialysis techniques. Explanations for the disparate findings of these studies will be put forth. Finally, suggestions regarding what we can recommend to patients are made.

A clustering of epidural abscesses in chronic hemodialysis patients: risks of salvaging access catheters in cases of infection.

The objective of this study was to investigate factors that might increase the risk of epidural abscesses in hemodialysis patients. The charts of all hemodialysis patients presenting with an epidural abscess over a period of 5 yr at Duke University Hospital and the Durham Veterans Administration Medical Center were reviewed for patient demographics, months on dialysis, vascular access, recently treated infections, signs and symptoms at presentation, and results of any surgical intervention. Ten patients developed an epidural abscess during a 5-yr period. Severe, debilitating back pain was the only consistent initial complaint. Eight patients had dual-lumen intravenous catheters for hemodialysis access, and five patients had or were receiving parenteral antibiotics for catheter salvage. There were no consistent physical, clinical, or laboratory findings. Surgical drainage of the abscess with removal of the hemodialysis catheters and parenteral antibiotics were required for cure in six patients. It was concluded that attempts at catheter salvage with parenteral antibiotics has significant risks for complications. Hemodialysis patients with recently treated or ongoing bacteremia who complain about severe and debilitating back pain with or without neurologic findings should raise the suspicion of an occult epidural abscess.

Medullary sponge kidney associated with congenital hemihypertrophy.

Medullary sponge kidney is a developmental disorder characterized by ectatic and cystic malformation of the collecting ducts and tubules. Clinical manifestations include urinary tract infections, renal stones, and hematuria. It can be associated with other developmental disorders. A case of medullary sponge kidney associated with congenital hemihypertrophy, complicated by nephrocalcinosis and nephrolithiasis, is reported here.

Maintenance of permanent hemodialysis vascular access patency.

The morbidity and mortality of maintenance hemodialysis patients are in large part determined by the ability of the nephrologist, dialysis staff, and vascular surgeon to establish and maintain adequate vascular access. Primary arteriovenous fistulae are the preferred form of vascular access because they are the more likely to provide long-term complication-free access. In 1994, however, the majority of patients entering hemodialysis programs have vascular anatomy unsuitable for primary arteriovenous fistula creation. Synthetic fistulae are currently the more common form of vascular access. Unfortunately, this form of vascular access is more prone to thrombosis and infection. Thrombosis is the most common cause of vascular access loss. Venous stenoses account for the majority of thromboses but can be prospectively identified by performing routine measurements of venous dialysis pressure or urea recirculation. Prospective identification of venous stenoses followed by either angioplasty or surgical revision will improve fistula patency and enhance the quality of life of the hemodialysis population.

Metabolism of 22-oxacalcitriol by a vitamin D-inducible pathway in cultured parathyroid cells.

Catabolism of 22-oxacalcitriol (OCT) in parathyroid cells was compared to that of the parent hormone, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Catabolism of both compounds was greatly accelerated by pretreatment of the cells with 1,25-(OH)2D3 or OCT. The rate of degradation of OCT was slightly greater than that of 1,25-(OH)2D3. Excess unlabeled OCT or 1,25-(OH)2D3 inhibited metabolism of both tritiated substrates. Ketoconazole, a cytochrome P450 inhibitor, blocked catabolism of both compounds. The major OCT metabolite appeared to be 1,20-dihydroxy-22,23,24,25,26,27-hexanor-vitamin D3 which was not active in suppressing PTH secretion. We conclude that OCT appears to be metabolized by the same vitamin D-inducible side chain oxidation pathway that catabolizes other vitamin D compounds and that its higher than expected suppression of PTH secretion is not due to slower cellular metabolism.

Binding and metabolism of 1,25-dihydroxyvitamin D3 in cultured bovine parathyroid cells.

Several laboratories, including ours, have reported that receptors for 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] are decreased in parathyroid glands of uremic animals and patients. To elucidate the factors involved in receptor regulation in this tissue, we have characterized the receptor in primary cultures of bovine parathyroid cells. Extracts from these cells contain a single binding component that binds 1,25-(OH)2D3 with a Kd of 58 pM and sediments in sucrose density gradients at 3.4S, indicating the continued expression of the vitamin D receptor in these cells. Labeling of the intact parathyroid cells with tritiated 1,25-(OH)2D3 was maximal by 2 h, and binding affinity by this method was estimated to be 22 pM. Longer incubation of the cells with tritiated 1,25-(OH)2D3 resulted in a loss of specific binding to 10% maximal by 12 h. The decrease in binding correlated temporally with degradation of 1,25-(OH)2D3 in the medium. This metabolic activity was absent in vitamin D-deficient cells and was first detectable 3-4 h after the addition of 1,25-(OH)2D3, indicating that 1,25-(OH)2D3 induces its own metabolism in parathyroid cells. Replenishment of the cultures after 12 h with fresh tritiated 1,25-(OH)2D3 restored maximal binding, demonstrating that the loss of binding was not due to down-regulation of receptor. Inclusion of the cytochrome P450 inhibitor ketoconazole did not alter maximal binding at 2 h, but blocked both the metabolism of 1,25-(OH)2D3 and the decrease in binding after 3 h. In contrast to other cell types, such as osteosarcoma cells, no homologous up-regulation was seen in cultured parathyroid cells even after 12 h in the presence of 0.5 nM 1,25-(OH)2D3. Furthermore, receptor levels in preparations from cells treated for 20 h with unlabeled 1,25-(OH)2D3 at concentrations of 0.1, 1.0, and 10 nM were not different from controls. Thus, it appears that the vitamin D receptors in parathyroid cell cultures are not up-regulated by their ligand.