Hypophosphataemia after parathyroidectomy in chronic renal failure

Out of 24 patients receiving haemodialysis who were subjected to parathyroidectomy, 13 developed hypophosphataemia; this persisted for 3-52 weeks (mean 10.6 weeks). Before operation these 13 patients had had significantly higher plasma alkaline phosphatase activities (p less than 0.01) and significantly higher values in iliac crest bone biopsy samples for active resorption surface and active formation surface (p less than 0.05 in each case) than the group who remained normophosphataemic. Significantly more of the patients who remained normophosphataemic had shown periarticular calcification in preoperative skeletal radiographs (p less than 0.001). Hypophosphataemia may result from reduced mobilisation of phosphate from bone or its increased accretion into bone, and resorption of phosphate from periarticular mineral deposits may protect against development.

Plasma lecithin-cholesterol acyltransferase activities in uraemic patients

Plasma lecithin-cholesterol acyltransferase (LCAT) activity was measured in 43 haemodialysis and 15 peritoneal dialysis (CAPD) patients. LCAT activities in both groups of patients were significantly lower than those of normal subjects and did not correlate with any of the other biochemical parameters studied. The effect of intravenous administration of 100 U/kg of heparin on LCAT activity was examined in 21 haemodialysis patients and 19 normal subjects. Heparin inhibited LCAT activity by increasing plasma free fatty acid concentrations. LCAT remained inhibited throughout a dialysis session and returned towards pre-dialysis levels an hour after haemodialysis was discontinued. The cause of the low LCAT activities in the patients was not certain, but did not appear to be due to the presence of inhibitors in the uraemic plasma. The significance of these findings is discussed.

Response patterns to DL-carnitine in patients on maintenance haemodialysis

10 hypertriglyceridaemic hemodialysis patients were given dl-carnitine, 600 mg daily, for 8 weeks and then 1.2 g daily for 12 weeks. Serum total cholesterol, total triglyceride, high-density lipoprotein cholesterol and plasma free fatty acid (FFA), glucose, and immunoreactive insulin concentrations were measured at regular intervals during the treatment. Intravenous fat tolerance tests were performed in 9 patients. Plasma FFA concentrations fell and the post-heparin fractional clearance rate of Intralipid increased significantly after all-carnitine administration. While overall no clear-cut effect of dl-carnitine on serum lipids was found, two patterns of response to dl-carnitine could be distinguished: the 'paradoxic' response with a rise in serum triglyceride concentrations and the dual response to two different dosages of dl-carnitine.

Hyperlipidaemia in untreated nephrotic syndrome, increased production or decreased removal?

The relative importance of increased lipoprotein synthesis and decreased lipoprotein catabolism is examined in 13 patients with untreated nephrotic syndrome by the use of intravenous fat tolerance tests analysed in relation to other parameters of lipid metabolism. Increased lipoprotein synthesis in nephrotic patients was indicated by the fact that at a given fractional clearance rate of Intralipid (K2), nephrotic patients had higher serum TG concentrations than did control subjects. A defect in lipoprotein catabolism was also suggested by the frequent finding of intermediate density lipoproteins on electrophoresis and the marginally low (p = 0.05) mean K2 in nephrotic patients. A highly significant (p less than 0.001) positive correlation between HDL-cholesterol concentrations and postheparin fractional clearance rates (K'2) of Intralipid led to the speculation that in the severe nephrotic state (albumin less than 20 g/l) the loss of high density lipoproteins may contribute to the hyperlipidaemia.

Fat clearances and hyperlipidaemia in renal allograft recipients--the role of insulin resistance

The mechanism of hyperlipidaemia in renal allograft recipients was investigated in 19 patients randomly selected from a cohort of 54 patients with functioning renal allografts. Serum cholesterol, triglyceride and high-density lipoprotein cholesterol concentrations as well as plasma immunoreactive insulin levels were measured in fasting blood samples. Intravenous fat tolerance tests were performed before and 15 min after heparin administration. Renal allograft recipients had reduced fractional clearance rates of Intralipid and a positive correlation was demonstrated between plasma immunoreactive insulin levels and serum triglyceride concentrations. Plasma immunoreactive insulins also correlated inversely with fractional clearance rates of Intralipid. It was concluded that both increased production and decreased removal of lipoproteins contribute to the hyperlipidaemia and that insulin resistance due to corticosteroids was the centre of the problem.

Three years' experience of continuous ambulatory peritoneal dialysis

Patients on continuous ambulatory peritoneal dialysis (CAPD) were studied for three years. 29 of them who had been on CAPD for six months or more were compared with patients on intermittent peritoneal dialysis (IPD) and on haemodialysis (HD). CAPD patients had significantly higher levels of HDL-cholesterol than HD patients. Urea, potassium, phosphate, and urate levels were significantly lower, and haemoglobin levels significantly higher, than in the IPD and HD groups. 43 CAPD patients studied had a peritonitis rate of 2.22 episodes per patient-year. CAPD offers an alternative form of dialysis to those unsuitable for HD, but until peritonitis rates can be reduced CAPD cannot rival HD as a long-term treatment.

Vitamin A toxicity and hypercalcaemia in chronic renal failure

Serum vitamin A concentrations were measured in 38 patients undergoing haemodialysis, 24 of whom were taking multivitamin preparations containing vitamin A. Vitamin A concentrations were significantly higher in patients undergoing haemodialysis than in 28 normal controls (p less than 0.001). Patients taking vitamin A supplements had significantly higher vitamin A concentrations than those not taking them (p less than 0.05), and hypercalcaemic patients had higher concentrations than normocalcaemic patients (p less than 0.005). Withdrawal of vitamin A supplements in seven patients caused significant falls in serum vitamin A concentrations and plasma calcium concentrations (p less than 0.01 at two and three months in both cases) and in plasma alkaline phosphatase concentrations (p less than 0.01 at two months). Vitamin A toxicity can contribute to hypercalcaemia in patients undergoing haemodialysis, probably by an osteolytic effect. Multivitamin preparations containing vitamin A should therefore be prescribed with caution in these patients.

The role of multiple pharmaco-therapy in the pathogenesis of hyperlipidemia after renal transplantation

A study was undertaken in 54 renal allograft recipients to evaluate the multiple factors contributing to the pathogenesis of hyperlipidemia after renal transplantation. Serum triglyceride concentrations were found to correlate positively with the cummulative prednisolone dose, and with abdominal skin fold thickness. Serum cholesterol concentrations correlated significantly with serum creatinine concentrations. Patients on beta adrenergic blocking agents had lower plasma free fatty acid concentrations and patients on diuretics had higher serum triglyceride concentrations. The implication of these findings are discussed.

Sixteen months experience with cyclosporin-A in human kidney transplantation

CY-A is a potent immunosuppressive agent and can prevent graft rejection. In our experience hirsutism and viral infections are marked. Lymphomas may be more common in CY-A-treated patients than in those treated conventionally. Smaller doses of CY-A given for shorter periods before conversion to conventional treatment may be a better way to use this new agent.

Plasma hydroxyproline fractions in patients with dialysis osteodystrophy

Plasma hydroxyproline fractions were measured in 17 normal subjects and in 54 patients on maintenance haemodialysis therapy (MHT) with various degrees of dialysis osteodystrophy. On the basis of both radiological and histological findings these patients were divided into three groups: radiologically normal, histologically normal and those with osteitis fibrosa. The mean total plasma hydroxyproline concentrations were significantly elevated in all groups of MHT patients. However, these increases were mainly due to peptide-bound and free hydroxyproline fractions. The highest values for these two fractions were found in patients with osteitis fibrosa. The free to peptide-bound hydroxyproline ratio was not significantly altered in the majority of patients on dialysis; the mean ratio was significantly lower in patients with osteitis fibrosa when compared with patients with no histological evidence of bone disease. This finding would suggest that there is no inhibition of hydroxyproline catabolism in patients on haemodialysis and the measurements of both free and peptide-bound hydroxyproline were equally sensitive in identifying patients with osteitis fibrosa.

The effects of vitamin A toxicity on calcium and lipid metabolism in chronic renal failure

Serum vitamin A levels were high in haemodialysis patients, and were found to correlate with plasma calcium, triglyceride, cholesterol and insulin levels. Vitamin A containing multivitamin supplements were found to contribute to increased serum vitamin A levels, and their withdrawal in seven patients caused a significant decrease in serum vitamin A and calcium levels, with no effect on lipid levels. Vitamin A containing preparations should therefore be prescribed with caution in these patients.

Comparison of radioisotope methods for the measurement of phosphate absorption in normal subjects and in patients with chronic renal failure

1. Intestinal phosphate absorption was measured in normal subjects, in patients with chronic renal failure, and in post-transplant patients, by a double isotope technique involving oral administration of 32P and simultaneous intravenous injection of 33P with subsequent deconvolution analysis. 2. By this technique intestinal phosphate absorption has been shown to have two components: an initial rapid phase, which is completed by 3 h, and a slower more prolonged phase, which continues beyond 7 1/2 h. 3. Phosphate malabsorption has been demonstrated in chronic renal failure and transplant patients, which is accounted for by impairment of the initial rapid phase of absorption. 4. Results obtained by deconvolution analysis have been compared with other estimates of phosphate absorption obtained from analysis of 32P radioactivity curves alone. 5. The fractional hourly rate of absorption and the plasma 32P radioactivity at 60 min corrected for extracellular fluid volume provided the best approximations to the result obtained by deconvolution analysis, with respect to both the maximal rate of phosphate absorption and cumulative percentage phosphate absorption.

Fat clearance before and after heparin in chronic renal failure--haemodialysis reduces post-heparin fractional clearance rates of intralipid

The effect of heparin on the kinetics of fat removal was studied in 15 subjects and it became apparent that the fat tolerance test could be performed after the administration of heparin. Therefore, fractional clearance rates of Intralipid were determined before and after heparin in three groups of patients: 18 in chronic renal failure, 11 on peritoneal dialysis and 17 on haemodialysis. Patients on peritoneal dialysis and on haemodialysis had similar serum triglyceride concentrations and comparable fractional clearance rates of Intralipid before heparin was given. However, the latter had significantly smaller increases in fractional rates of Intralipid clearance after the administration of heparin. Either gradual diminution of releasable releasable enzymes by regular heparinisation or activator concentrations becoming rate-limiting could be responsible for the low post-heparin fractional clearance rates observed in haemodialysis patients.

Human calcitonin in the treatment of renal osteodystrophy

The effects of HCT (0.5 to 1 mg/day subcutaneously), used singly and in combination with a small dose of 1,25-(OH)2D3 (0.25 microgram/day by mouth), have been studied in 16 hemodialysis patients with hypercalcemic hyperparathyroid bone disease for a mean period of 6 months. An intitial improvement occurred in plasma hydroxyproline and hyperparathyroid hormone levels, but there were later rebound increases. There was little overall effect on bone histology, and 10 of the patients had side effects from treatment. HCT in this dose, alone or in combination with small doses of 1,25-(OH)2D3, does not appear to have a major role in the treatment of the hypercalcemic hyperparathyroidism of renal osteodystrophy.

Nocturnal polyuria and saluresis in renal allograft recipients

The evolution of nocturnal polyuria and saluresis in renal allograft recipients was studied by comparing the day to night (D:N) ratios of urine volume and sodium excretion in 15 patients who had undergone transplantation less than one year previously (recent-transplant group) with those in 11 patients who had undergone transplantation at least one year previously. Eleven patients with chronic renal failure and 12 normal subjects served as controls. Patients in the recent-transplant group had significantly lower D:N ratios of urine volume and sodium excretion than the patients who had undergone transplantation at least a year before, while the ratios in this last group did not differ significantly from those in the normal subjects. Nocturnal polyuria and saluresis gradually subsided in five patients studied for three months. Chronic renal failure and uraemic autonomic neuropathy were unlikely causes of the nocturia. The patients in the recent-transplant group had significantly lower D:N ratios of urine volume than the controls with chronic renal failure, and the mean Valsalva ratio in eight of them was not significantly different from that in the normal subjects. An undue sensitivity of renal allografts to postural influences was proposed.

The response to 1,25-dihydroxycholecalciferol and to dihydrotachysterol in adult-onset hypophosphataemic osteomalacia

The biochemical changes observed in a patient with adult-onset hypophosphataemic osteomalacia after three weeks treatment with 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) followed by dihydrotachysterol (DHT) are reported. The treatment with 1,25-(OH)2D3 resulted in restoration of intestinal phosphate absorption to normal with a small rise in plasma phosphate concentration; there was no significant change in tubular reabsorption of phosphate. The tubular reabsorption of bicarbonate, which was initially low, returned almost into the normal range with normalisation of plasma bicarbonate concentration. Aminoaciduria decreased. There were no changes in plasma or urinary calcium but immunoreactive parathyroid hormone (i-PTH) which was initially elevated fell but still remained above the normal range. These changes were maintained after replacing the 1,25-(OH)2D3 treatment with dihydrotachysterol (DHT).