Plasma concentrations of atrial natriuretic peptide, arginine vasopressin and hormones of the renin-angiotensin system in patients with end-stage renal disease

Plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), plasma renin activity (PRA) and aldosterone, were measured before and after 3 h of hemodialysis in 9 patients with end-stage renal disease on maintenance hemodialysis. Hormone concentrations were also determined in the same patients on a separate occasion after 1 h of ultrafiltration (UF). Plasma concentrations of ANP were significantly higher in the patients with ESRD than in a normal reference population and declined after both 1 h and 3 h of hemodialysis. Plasma concentrations of ANP failed to exhibit a significant decline after 1 h of UF. Plasma AVP concentrations were not significantly different after either hemodialysis or UF, while plasma aldosterone concentrations fell with hemodialysis. The decline in plasma aldosterone concentrations paralleled the decrease in dialysis-induced fall in serum potassium concentrations. There was no correlation between the blood pressures, heart rate, interdialytic weight gain and estimated fluid overload and any of the hormones measured except for the plasma renin activity (PRA) which correlated significantly with the systolic blood pressure. The data suggest that ANP may not be a major factor in blood pressure regulation in normotensive patients with ESRD and its elevation in patients with ESRD is most likely due to fluid overload and atrial distention as well as a possible reduction in its metabolic clearance in renal insufficiency. The fall in plasma ANP following hemodialysis is not due to its removal by dialysis but is most likely due to a reduction in ANP production caused by dialysis-induced correction of hypervolemia.     

Severe hyperkalemia caused by indomethacin and potassium supplementation

Treatment with a combination of indomethacin and potassium chloride supplementation resulted in severe hyperkalemia in a patient with Bartter's syndrome. The clinical and electrocardiographic findings and hyperkalemia improved promptly with intravenous administration of sodium bicarbonate, glucose, and insulin, discontinuation of the potassium supplement, and reduction of the indomethacin dose. This case suggests that life-threatening hyperkalemia can occur when indomethacin and potassium supplementation are prescribed simultaneously in Bartter's syndrome.     

Renal pathology in end-stage renal disease associated with paraplegia

In the present study we report the renal pathological findings from autopsy material along with relevant clinical data on 21 spinal cord injury patients with end-stage renal disease (SCI-ESRD) treated with maintenance haemodialysis. These data are compared with the relevant clinical and post-mortem findings on 43 ambulatory dialysis patients who expired during the same time period. The SCI-ESRD patients exhibited markedly different clinical and renal histopathological data when compared to the ambulatory--ESRD group. Chronic pyelonephritis and amyloidosis dominated the findings and were the major causes of renal insufficiency. Acute pyelonephritis, papillary necrosis, calculous disease, pyonephrosis and perinephric abscess formation were also more frequently present in the SCI-ESRD patients. Hypertension and nephrosclerosis, which were common findings in the ambulatory--ESRD patients were comparatively rare in the SCI-ESRD patients. In addition, the incidence of acquired cystic disease (ACD) was considerably less in the SCI-ESRD group. Although the reasons for these findings are not entirely clear several possible explanations are given. Infection with gram negative sepsis was the predominant cause of death in the SCI-ESRD patients, while death secondary to cardiovascular disease predominated in the ambulatory-ESRD group. Furthermore, the urinary tract and infected decubitus ulcers were determined to be the major source for sepsis in the SCI patients. From these findings it would follow that more effective prevention and control of these infections would result in not only a lower incidence of renal failure but also a substantially reduced morbidity and mortality in chronic SCI.     

Intestinal absorption of 5-methyltetrahydrofolate in experimental uremia

Folate deficiency and megaloblastic anemia occur in chronic renal failure. However, the possible role of intestinal malabsorption as a cause of the reported deficiency has not been investigated. Therefore, we examined the intestinal absorption of 5-methyltetrahydrofolate in rats made uremic by subtotal nephrectomy using in vivo perfusion technique and in vitro everted sac technique. The results were compared with those obtained in a group of sham-operated rats with normal renal function. The amount of 5-methyltetrahydrofolate absorbed in vivo was significantly lower in the uremic animals as compared to the control group. In contrast, no significant difference was found in the absorption of 5-methyltetrahydrofolate in vitro in the two groups. To mimic the uremic environment, the in vitro studies were repeated using jejunal sacs from normal animals filled with either buffer solution, or sera from uremic patients before and after dialysis. Their results showed a marked suppression of 5-methyltetrahydrofolate absorption with predialysis sera and a significant improvement with post dialysis sera. We conclude that intestinal absorption of 5-methyltetrahydrofolate is impaired in uremia. The results of the in vitro experiments suggest that the observed transport defect is due to some influence of uremic environment rather than to an acquired intrinsic defect of enterocytes in uremia.     

Compression neuropathy subsequent to renal transplantation.

Compression neuropathy occurred in 7 patients who underwent renal transplantation. The neuropathy occurred on the same side as the surgery and was associated with the use of selfretaining retractors. Other contributing factors were presence and degree of uremia and diabetes. We suggest that self-retaining retractors be used carefully and length of application reduced to a minimum. Efficient dialysis prior to transplantation may decrease the incidence and severity of neurologic deficit by reducing the extent of uremia.     

Impaired intestinal absorption of vitamin D3 in azotemic rats

Changes in vitamin D metabolism and their effect on calcium and bone metabolism in uremia have been extensively studied. However, the possible effect of uremia on intestinal absorption of vitamin D has not been investigated. We determined the rate of intestinal absorption of vitamin D3 in uremic and normal rats using a well-defined in vivo perfusion technique under identical experimental conditions. The rate of jejunal absorption of vitamin D3 in uremic animals (5.09 +/- 1.87 pmol/100 cm/h) was significantly less (p less than 0.001) than that found in the control animals (11.5 +/- 1.6 pmol/100 cm/h). While the underlying mechanism(s) of the observed reduction in vitamin D absorption in uremia is not known, its recognition adds another dimension to the previously recognized abnormalities of vitamin D metabolism in uremia.     

Massive spontaneous hemothorax associated with Von Recklinghausen's disease

A 30-year-old woman with Von Recklinghausen's disease was admitted to our hospital because of sudden onset of dyspnea and syncope. A chest roentgenogram showed a massive right pleural effusion and insertion of an intercostal tube drained 1,600 cc of blood. A computed tomographic chest scan with contrast revealed a hyperdense mass in the right paravertebral area. At thoracotomy, retained clotted hemothorax and continued bleeding from tumor vessels was noted. The apex of the right hemithorax and the tumor location was packed. The pathologic diagnosis was ganglioneuroma and follow-up of the patient for 2 years after re-thoracotomy and removal of the packs revealed no complication and morbidity. We report this case to emphasize the importance of early recognition and prompt surgical intervention in spontaneous hemothorax associated with Von Recklinghausen's disease.     

Naïve and central memory T-cell lymphopenia in end-stage renal disease

End-stage renal disease (ESRD) is associated with increased propensity to infections, diminished response to vaccination, impaired cell-mediated immunity, and reduced CD4+/CD8+ T-lymphocyte ratio. Four subsets of CD4+ and CD8+ T cells have been recently identified: na?ve cells (as yet uncommitted), central memory (CM) cells (previously programmed), and CD45RA-positive and CD45RA-negative effector memory (EM) cells (programmed to perform specific effector functions). The effect of ESRD on subpopulations of T lymphocytes is unclear and was studied here. Twenty-one hemodialysis patients and 21 age-matched controls were studied. Pre- and post-dialysis blood samples were obtained and analyzed by three-color flow cytometry. CD4+/CD8+ ratio and the numbers of the na?ve and CM CD4+ and CD8+ T cells were significantly reduced, whereas the numbers of EM CD4+ and CD8+ T cells were unchanged in the ESRD group. The reduction of the na?ve and CM T-cell counts in the ESRD group was associated with increased apoptosis of these cells. Negative correlations were found between severity of azotemia, oxidative stress, and hyperphosphatemia with the number of na?ve T cells. Comparison of diabetic with non-diabetic ESRD patients revealed higher numbers of total CD8+ cells and EM CD8+ T cells in the diabetic group. Dialysis did not significantly change the na?ve and CM CD4+ or CD8+ cell counts, but significantly lowered CD8+ EM cell count. Thus, ESRD results in increased apoptosis and diminished populations of na?ve and CM T lymphocytes. This phenomenon may, in part, contribute to the impaired immune response in this population.     

Event-related potential changes during hemodialysis

Uremia has been associated with a number of neuro-behavioral deficits. In this study, long-latency event-related potentials (ERP's) and the Symbol Digit Modalities Test (SDMT) were used to assess changes in cortical function due to dialysis treatment. Ten chronic renal failure patients, maintained on hemodialysis, were tested. ERP and SDMT measures were taken immediately before and after dialysis. As a control for any practice effects or neurocognitive changes not associated with hemodialysis, the patients were also assessed with the same procedures on a day off dialysis. Significant increases in N2 and P3 amplitude were demonstrated following the dialysis treatment suggesting that a routine hemodialysis treatment increases the intensity of neural activation. Speed of cortical function, as indexed by ERP component latency and the SDMT, was not affected in any consistent manner by dialysis. However, changes during dialysis in the latency of late ERP components were correlated with changes in subject's serum electrolyte levels, indicating that the speed of cortical function is related to blood electrolyte levels. Differences between subjects in the pre-dialysis latency of the P3 component of the ERP was correlated with pre-dialysis levels of calcium and uric acid, as well as with performance on the SDMT.