Carmelo Loschiavo

A Prospective Controlled Trial on Effect of Percutaneous Transluminal Angioplasty on Functioning Arteriovenous Fistulae Survival

Balloon angioplasty (PTA) is an established treatment modality for stenosis in dysfunctional arteriovenous fistulae (AVF), although most studies showing efficacy have been retrospective, uncontrolled, and nonrandomized. In addition, it is unknown whether correction of stenosis not associated with significant hemodynamic, functional, and clinical abnormality may improve survival in AVF. This study was a prospective controlled open trial to evaluate whether prophylactic PTA of stenosis not associated with access dysfunction improves survival in native, virgin, radiocephalic forearm AVF. Sixty-two stenotic, functioning AVF, i.e., able to provide adequate dialysis, were enrolled in the study: 30 were allocated to control and 32 to PTA. End points of the study were either AVF thrombosis or surgical revision due to reduction in delivered dialysis dose. Kaplan-Meier analysis showed that PTA improved AVF functional failure-free survival rates (P = 0.012) with a fourfold increase in median survival and a 2.87-fold decrease in risk of failure. Cox proportional hazard model identified PTA as the only variable associated with outcome (P = 0.012). PTA induced an increase in access blood flow rate (Qa) by 323 (236 to 445) ml/min (P < 0.001), suggesting that improved AVF survival is the result of increased Qa. PTA was also associated with a significant decrease in access-related morbidity by approximately halving the risk of hospitalization, central venous catheterization, and thrombectomy (P < 0.05). This study shows that prophylactic PTA of stenosis in functioning forearm AVF improves access survival and decreases access-related morbidity, supporting the usefulness of preventive correction of stenosis before the development of access dysfunction. It also strongly supports surveillance program for early detection of stenosis.

Clinical Features of Patients with Solitary Kidneys

A clinical study was performed in 2 groups of patients with solitary kidneys, followed for 11-146 months. Group 1 had 9 patients (7 males and 2 females, aged between 23 and 68 years) with unilateral renal agenesis. Group 2 had 13 patients (9 females and 4 males, aged between 27 and 70 years) who underwent unilateral nephrectomy for the following reasons: hydronephrosis secondary to ureteropelvic junction stenosis, 7 patients; renal trauma, 4 patients; benign neoplasia, 2 patients. During the follow up, urinary protein excretion of more than 300 mg/day was observed in 9 patients, 3 in group 1 and 6 in group 2. Eleven patients, 8 in group 1 and 3 in group 2, were hypertensive (diastolic blood pressure higher than 95 mm Hg). Hyperuricemia was observed in 14 patients, 10 in group 1 and 4 in group 2. Seven patients, 4 in group 1 and 3 in group 2, had a significant deterioration of renal function. Neither proteinuria nor renal failure were observed before at least 10 years had elapsed since the anatomic condition of solitary kidney had been established. A surgical renal biopsy was performed in 1 patient with unilateral renal agenesis and showed focal glomerular sclerosis. This study adds support to the view that the reduction of 50% of the renal tissue may be a risky situation in humans as well as in animals.

Bone Histology and Calcium Metabolism in Patients with Nephrotic Syndrome and Normal or Reduced Renal Function

Bone histology and its relationship with calcium metabolism was evaluated in adult patients with nephrotic syndrome: 29 had normal renal function (GFR 103 +/- 4 ml/min/1.73 m2) (group 1) and 20 had renal insufficiency (GFR 31 +/- 4 ml/min/1.73 m2) (group 2). In group 1, serum PTH, 1.25-HCC and 24.25-HCC levels were normal, while 25-HCC values were reduced. Bone histology was normal in 76% of the patients, while 17% had isolated osteomalacia and 7% an associated bone resorption. Group 2 showed a higher incidence of bone resorption when compared with a matched group of patients with renal failure and no proteinuria (40% vs. 13%) and a comparable frequency of isolated mineralization defect (25% vs. 34%). PTH levels were definitely increased and serum total calcium and all the vitamin D metabolites were reduced. A significant correlation between the apparent duration of the disease and the severity of osteodystrophy was found only in group 2. In conclusion, no constant derangement of calcium metabolism and bone histology is evident in patients with nephrotic syndrome and normal renal function, while patients with persistent proteinuria are at high risk of osteodystrophy even in the early phases of renal failure.

Medullary Sponge Kidney and Hyperparathyroidism -a Puzzling Association

28 adult patients with radiological evidence of medullary sponge kidney (MSK) were studied. Hypercalcemia and increased serum parathyroid hormone (PTH) values were found in 10 patients (36%). In 7 of them, parathyroid surgery was performed: a single adenoma was found in 6 cases and multiple-gland hyperplasia in 1 case. After surgery, 3 patients had normalization of calcium metabolism; 4 patients had persistence of hypercalciuria with progressive increase in serum PTH values (and recurrence of the adenoma in 1 case). Of the remaining patients, 10 (36%) had definite or marginal hypercalciuria, resulting from renal calcium leak in 8 and from intestinal calcium hyperabsorption in 2 of them. In 8 patients (28%), no evidence of disordered calcium metabolism was found. The association of MSK and hyperparathyroidism is not a chance occurrence. MSK might be a renal anatomical complication of primary hyperparathyroidism, or it might be regarded as an anatomic substrate--or rather as a consequence--of prolonged hypercalciuria, regardless of its pathogenesis. The lack of disordered calcium metabolism in a considerable number of patients, however, shows that the enigma of MSK is still far from being solved.

Nephrotic Syndrome During 2-Mercapto-Propionyl-Glycine (Thiola) Therapy

The occurrence of the nephrotic syndrome in 3 patients treated for 1–8 months with 2-mercapto-propionyl-glycine (Thiola) (at doses ranging from 0.750 to 2.000 g/day) is reported. The drug had been administered for chronic active hepatitis in 1 patient and for cystinuria in the remaining patients. Percutaneous renal biopsies, obtained in all patients and examined at light microscopy, immunofluorescence and electron microscopy, showed ‘minimal change’ nephropathy in 2 patients and membranous glomerulonephritis in the 3rd patient. In all patients, complete remission of the nephrotic syndrome and, eventually, disappearance of proteinuria were observed 15–120 days after discontinuation of Thiola. It is suggested that this drug may act either through an antigenie mechanism, akin to that of penicillamine, or through a sensitization mechanism, both of them being able to cause the nephrotic syndrome.