Jayson Rapoport

Losses of 1,25- and 24,25-dihydroxycholecalciferol in the peritoneal fluid of patients treated with continuous ambulatory peritoneal dialysis.

We measured peritoneal losses of the active vitamin D metabolites 1,25(OH)2D3 and 24,25(OH)2D3 in patients receiving continuous ambulatory peritoneal dialysis (CAPD). The serum concentration of 24,25(OH)2D3 was considerably lower than in hemodialysis patients. The serum concentration of 1,25(OH)2D3 was undetectable and rose to levels similar to those in hemodialysis patients only after loading with much higher oral doses of 1-alpha-vitamin D3 than those received by hemodialysis patients. Losses of both metabolites in peritoneal fluid were considerable, averaging approximately 6-8% of the plasma pool per day. These losses lead to low serum levels of these active vitamin D metabolites in CAPD patients, which may be an important factor in exacerbating renal osteodystrophy. Our results indicate the need for increased replacement doses of vitamin D metabolites in CAPD patients.

Reversal of Nephrotic Syndrome due to AA Amyloidosis in Psoriatic Patients on Long-Term Colchicine Treatment

A case of nephrotic syndrome due to AA amyloidosis in a young woman suffering from erythrodermic psoriasis and psoriatic arthropathy is reported. The nephrotic syndrome regressed completely during long-term (57 months) colchicine treatment. There are 39 case reports in the literature of psoriasis associated with amyloidosis. More than 85% of these patients had concomitant arthropathy. This suggests that arthritis may be an important factor in the appearance of amyloidosis. 59% of psoriatics with amyloidosis had renal failure and 56% of them died shortly after diagnosis of amyloidosis. These observations support the view that amyloidosis associated with psoriasis is an aggressive disease that may be fatal. However, the clinical course of our patient suggests that renal amyloidosis associated with psoriasis may be successfully treated by colchicine.

Enhancement of 24,25-Dihydroxyvitamin D Levels in Patients Treated with Continuous Ambulatory Peritoneal Dialysis

We measured 24,25-dihydroxyvitamin D [24,25(OH)2D] levels in patients treated with chronic ambulatory peritoneal dialysis (CAPD), before and after receiving vitamin D2 or 1 alpha-hydroxyvitamin D3 (1 alpha-OH-D3). Vitamin D2 administration led to an increase in 25-hydroxyvitamin D (25-OH-D) and a concomitant rise in 24,25(OH)2D. No change was observed in 1,25-dihydroxyvitamin D [1,25(OH)2D]. Administration of 1 alpha-OH-D3 resulted in an increase in 1,25(OH)2D3, and a concomitant rise in 24,25(OH)2D, but no change in 25-OH-D3. Thus, 24,25(OH)2D levels may be increased in CAPD patients by raising 25-OH-D levels, or by raising 1,25(OH)2D3 levels. Since the latter enhances specifically the renal 24-hydroxylase enzyme, we conclude that this enzyme is present in CAPD patients with kidneys in situ, and may be stimulated by adequate 1,25(OH)2D3 levels. Thus, administration of 1 alpha-OH-D3 to CAPD patients with kidneys in situ seems to be sufficient to obtain normal levels of 1,25(OH)2D3 and 24,25(OH)2D3. However, anephric patients require vitamin D2 in addition as a source of 25-OH-D, the substrate for extrarenal production of 24,25(OH)2D.

Nephrotic Syndrome Associated with Transitional Cell Carcinoma of the Bladder

We describe the occurrence of a nephrotic syndrome in association with transitional cell carcinoma of the bladder. The proteinuria disappeared several weeks after removal of the tumor. Light and electron microscopy were compatible with a minimal-change lesion, but immunofluorescence showed linear immunoglobulin deposition. Immunoglobulins eluted from the tumor reacted specifically with the kidney and vice versa. We conclude that antibody formation against a specific component of basement membrane common to both kidney and tumor gave rise to the nephropathy in this case.

Oral administration of 24,25(OH)2D3 suppresses the serum parathyroid hormone levels of dialysis patients.

We measured the serum parathyroid hormone (PTH) levels in 20 patients treated with continuous ambulatory peritoneal dialysis before and after oral treatment with 24,25-dihydroxyvitamin D3- 24,25(OH)2D3. This metabolite was given in addition to existing treatment with 1 alpha-OH-D3 and calcium carbonate. Administration of 24,25(OH)2D3 led to a significant decrease in PTH levels (intact molecule) from 382 +/- (SE) 65 to 245 +/- 54 pg/ml in 9 patients whose initial levels were extremely high (p = 0.01). No side effects were observed. On the average, calcium values were unchanged and within the normal range throughout the study period; however, a few episodes of mild asymptomatic hypercalcemia occurred which responded quickly to reduction of the calcium carbonate dosage. The present study suggests that oral administration of 24,25(OH)2D3 combined with 1 alpha-OH-D3 is safe and capable of suppressing the raised serum PTH levels of end-stage renal disease patients without the danger of significant hypercalcemia.

323 NIGHT HEART RATE IS ASSOCIATED WITH HIGH RISK FOR CARDIOVASCULAR DISEASE

Background: In order to study the relationship between heart rate (HR) and cardiovascular risk (CVR) in patients with essential hypertension (HTN) we used ambulatory blood pressure monitoring (ABPM). Table. No title available. Methods: 1140 patients (age18-88 years; female/male 491/649; body mass index (BMI) 18.0–45.1 kg/m2) were divided into high and low CVR groups. Criteria for high CVR were: type 2 diabetes (treated or HBA1C≥7%); chronic kidney disease (albumin/creatinine ratio >30 mg/g and/or GFR<60 ml/min/1.73m2) and documented history of myocardial infarction; coronary artery bypass graft; congestive heart failure, cerebrovascular accident and peripheral vascular disease. Data for blood pressure (BP) and HR were adjusted for gender (male), age (56 years) and BMI (25 kg/m2). Results: 156, 146 and 74 patients suffered from diabetes (DM), chronic kidney disease (CKD) and DM+CKD, respectively. Daytime and nighttime BP was similar, whereas HR was significantly higher in subjects with high CVR. Antihypertensive treatment was significantly different between groups (table). Multivariate stepwise analysis showed that in addition to number of antihypertensive drugs night HR was a strong independent variable of high CVR (p<0.0001). Conclusion: Nighttime (rest) HR, as assessed by ABPM, appears to be an important prognostic factor for CVR.

The Unique Chemical Composition of Nephrocalcinosis in Experimental Renal Insufficiency, Disturbances of Cellular Calcium Metabolism, and Protective Effect of Verapamil Against Nephrocalcinosis

Clinical consequences of the deranged calcium metabolism are multiple. Mostly they manifest themselves dramatically as do renal stones or calcification of the soft tissues. These entities were known to ancient physicians and the Hippocrates recommendation to avoid large quantities of milk for an infant’s nursing (some should be substituted with a diluted wine) represents an indication of a deep intuitive awareness of what Sir Hamphry Davy will refer to in 1808 as calcium, and of its role in the “milk-alkali syndrome.”