[Rescue endovascular revascularization in two patients with bilateral atherosclerotic renal artery occlusion]. / Rivascolarizzazione endovascolare di salvataggio in due pazienti con occlusione aterosclerotica bilaterale dell'arteria renale.

Renal artery stenosis is found in 2% and 40% of general and high cardiovascular risk populations, respectively. Atherosclerotic renal artery stenosis (ARAS) has become an increasingly recognized clinical condition, especially in older or otherwise atherosclerosis-prone populations. This increase in prevalence has led to a dramatically increased use of percutaneous transluminal renal angioplasty. Randomized trials have failed to demonstrate any superiority of renal revascularization over medical therapy as far as control of hypertension, mortality or cardiovascular events is concerned. However, in this report we present two cases in which rescue endovascular revascularization in patients affected by bilateral ARAS permitted withdrawal from hemodialysis treatment and the restoration of a certain degree of renal function. In conclusion, for certain carefully-selected high-risk patients, renal revascularization may still have an important role. The two cases presented in this article are good examples of the extraordinary benefit that endovascular revascularization can bestow.

Fibromuscular dysplasia of renal arteries presenting with bilateral renal infarction in a young man.

Fibromuscular dysplasia (FMD) describes a group of conditions which cause nonatheromatous arterial stenoses, most commonly of the renal and carotid arteries, typically in young women. We report the case of a previously healthy 43-year-old white man presenting with acute bilateral flank pain. The pain was more severe on the left side. Initially treated for ureteral colic, he was transferred to the nephrology unit upon recognition of a rising serum creatinine. He was found to have FMD of bilateral renal arteries with resultant infarctions in both kidneys. He was treated with intravenous heparin and, then, warfarin at discharge. At a 16-month review, the patient remained pain-free with normal renal function and with antiplatelet and dual antihypertensive therapy. In conclusion, renal infarction complicating FMD is rare, with most cases involving causative cardiovascular risk factors, including coagulopathy, ischemic heart disease, atrial fibrillation or structural cardiac abnormalities, none of which was present in this case. What makes this case interesting are the clinically significant bilateral renal infarctions due to atypical asymmetric FMD in both kidneys in a young man.

The systemic capillary leak syndrome: a scarcely known nephrological entity.

The idiopathic systemic capillary leak syndrome (SCLS) is a rare life-threatening disorder characterized by periodic episodes of hypovolemic shock, due to plasma leakage from the intravascular to the interstitial space, as reflected by accompanying hypoalbuminemia, hemoconcentration and edema. Here we report the case of a 65-year-old woman affected by SCLS who required aggressive resuscitation with norepinephrine, steroids, albumin and crystalloids. Then, a long-term prophylaxis with a ß(2)-adrenergic receptor agonist and theophylline was started. In conclusion, though SCLS is a rare entity, the associated morbidity and mortality require the physician's awareness to provide timely therapy. Underrecognition in the medical community and rarity of this syndrome have precluded analysis by rational clinical trial designs that are necessary to determine more targeted and adequate therapy. This report is meant to enhance awareness of SCLS in the nephrology community.

The mckittrick-wheelock syndrome: a rare cause of severe hydroelectrolyte disorders and acute renal failure.

The McKittrick-Wheelock syndrome is a rare cause of severe hydroelectrolyte disorders and fluid depletion as a result of rectal tumor hypersecretion, which can lead to acute renal failure. We report the case of a 70-year-old female who presented with hyponatremia, hypokalemia, hypochloremia, and acute renal failure, due to a watery, mucinous diarrhea. A large rectal villous adenoma was discovered on ileocolonoscopy, and definitive management was achieved by removal of the tumor. In conclusion, reversal of the biochemical derangement is the cornerstone of successful management of the McKittrick-Wheelock syndrome. Then, immediate surgical resection of the tumor is the treatment of choice.

Does vitamin D receptor and calcium receptor activation therapy play a role in the histopathologic alterations of parathyroid glands in refractory uremic hyperparathyroidism?

BACKGROUND AND OBJECTIVES: Vitamin D receptor activation by vitamin D sterols and calcium-sensing receptor stimulation by cinacalcet are the most powerful treatments of secondary hyperparathyroidism. This study was aimed to assess a possible association between histopathologic changes of parathyroid tissue and treatment modality. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Studies were performed on 82 parathyroids of 22 adult white hemodialysis patients undergoing first parathyroidectomy. The type of hyperplasia and the distribution of chief and oxyphil cells, expressed as oxyphil/chief cell ratio, were assessed. Three groups could be studied according to treatment modality: group A consisted of 6 patients who were treated with cinacalcet, intravenous calcitriol, and phosphate binders; group B consisted of 6 patients who were treated with intravenous calcitriol and phosphate binders, and group C consisted of 10 patients who were treated with phosphate binders alone. RESULTS: Sixty-eight (82.9%) out of 82 glands removed showed nodular hyperplasia. It was more frequent in groups A and B than in group C. A stepwise forward logistic regression model showed that the probability of nodular hyperplasia was higher in patients who were on calcitriol and/or cinacalcet therapy, in female gender and in patients with a higher body mass index. Oxyphil/chief cell ratio also was significantly different among the three groups. Cinacalcet treatment was the only predictor of this ratio. CONCLUSIONS: An association was found between calcitriol and/or cinacalcet therapy and a high prevalence of nodular hyperplasia, and between cinacalcet therapy and high oxyphil/chief cell ratio. The meaning of the observed associations remains uncertain.

Development and validation of bioimpedance analysis prediction equations for dry weight in hemodialysis patients.

BACKGROUND: Accurate assessment of hydration status and specification of dry weight (DW) are major problems in the clinical treatment of hemodialysis (HD) patients. Bioelectrical impedance analysis (BIA) has been recognized as a noninvasive and simple technique for the determination of DW in HD patients. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: This study was designed to develop and validate BIA prediction equations for DW in HD patients. It included white adults (1540 disease-free adults with normal body mass index [BMI] and 456 prevalent and 27 incident HD patients). All participants underwent at least one single-frequency BIA measurement (800 muA and 50 kHz alternating sinusoidal current with a standard tetrapolar technique). The BIA variable measured was resistance (R). Data of 1463 (95% of the cohort) disease-free individuals with normal BMI (prediction sample) were used to establish best-fitting BIA prediction equations of body weight. The latter were cross-validated in the residual 5% subset (77 individuals) of the same cohort (validation sample). RESULTS: Multiple regression analysis showed a significant relationship among body weight, R, age, and height in 739 men (R(2) = 0.82, P < 0.0001) and among body weight, R, and height in 724 women (R(2) = 0.68, P < 0.0001) in the prediction sample. The Bland Altman analysis showed a mean difference between predicted and measured body weight of 0.3 +/- 1.0 kg (95% confidence interval +/- 2.0 kg) in the validation sample. The BIA prediction equations that were obtained in disease-free individuals with normal BMI were applied to a cohort of 456 prevalent HD patients: The mean difference between achieved and estimated DW was 0.1 +/- 1.0 kg (P = 0.53) in men and -0.3 +/- 1.0 (P = 0.76) in women. Finally, BIA prediction equations were tested in a cohort of 27 incident HD patients. The mean difference between predicted and achieved DW was -0.6 +/- 1.0 kg (P = 0.76) in men and 0.6 +/- 1.0 (P = 0.50) in women. CONCLUSIONS: This study was able to develop and validate BIA prediction equations for DW in HD patients. They seem to be a promising tool; however, they still need external validation.

Post-parathyroidectomy serum phosphate kinetics is peculiar to female hemodialysis patients with a high body mass index.

BACKGROUND: Persistent hyperphosphatemia is one of the most important factors in the development of secondary hyperparathyroidism (sHPTH). Recently, we demonstrated that a higher body mass index (BMI) and female gender could predispose to a larger phosphate (P) body burden, thereby influencing the severity of sHPTH. METHODS: This prospective study aimed to verify if these two risk factors, i.e. BMI and female gender, also influenced calcium (Ca) and P kinetics in the immediate post-parathyroidectomy (PTx) period in 42 consecutive adult Caucasian anuric hemodialysis (HD) patients referred for first PTx. Serum Ca and P were measured pre-PTx and on the 5 consecutive post-PTx days; serum immunoreactive parathyroid hormone (iPTH) and alkaline phosphatase (ALP) levels were measured pre-PTx and 3 days post-PTx. RESULTS: Ablation of parathyroid tissue determined a significant reduction in serum iPTH, ALP, Ca and P (p = 0.001). The stratification of the cohort into four groups according to the cut-off value of BMI = 25 kg/m(2) and according to gender showed the following: males and females with BMI >25 kg/m(2) (analyzed both separately and as a subgroup including males and females) had significantly higher pre-PTx serum P levels, when compared with the respective sub-groups with BMI <25 kg/m(2) (p < 0.01); a significantly higher mean area under the concentration curve (AUC) of serum P was observed in the high BMI group (males and females), when compared with the low/normal BMI group (p = 0.03); the serum P kinetics in the 5 post-PTx days did not differ between the two groups of male patients (low/normal BMI males vs. high BMI males), whereas a significantly higher mean serum P AUC was observed in the high BMI female patients, when compared with the low/normal BMI female patients (p = 0.003); finally, the serum P kinetics in the 5 post-PTx days did not differ between the two groups of low/normal male and female patients, whereas a significantly higher mean serum P AUC was observed in the high BMI female patients, when compared with the high BMI male patients (p = 0.006). A linear multiple regression analysis with the serum P AUC of each patient as a dependent variable and BMI, gender, age and dialysis duration as independent variables showed that BMI (p = 0.0001) and female gender (p = 0.001) were independent predictors of the serum P AUC. CONCLUSIONS: High BMI and female gender are associated with peculiar serum P kinetics in the immediate post-PTx period, suggesting the existence of a larger P body burden in high BMI female HD patients. The existence of a larger P pool exclusively based on serum P kinetics prompts the need for further studies to better understand such intriguing aspects of bone pathophysiology in response to parathyroid gland removal in chronically uremic patients.

A high body mass index and female gender are associated with an increased risk of nodular hyperplasia of parathyroid glands in chronic uraemia.

BACKGROUND: A persistent hyperphosphataemia represents one of the most important factors in the development of secondary hyperparathyroidism (sHPTH). The present prospective study was designed in order to test the hypothesis that a higher body mass index (BMI) may predispose to a larger body burden of phosphate (P), influencing by that way the severity of sHPTH. METHODS: Histological studies were performed on 168 parathyroid glands of 42 consecutive adult Caucasian haemodialysis patients (20 males and 22 females) referred for first parathyroidectomy (PTx): each parathyroid gland was graded as 0, when only or mainly diffuse hyperplasia was found, or as 1, when only or mainly nodular hyperplasia was found. Thus, parathyroid histology was scored on a 5-point scale: 0 = diffuse hyperplasia in the four glands; 1 = nodular hyperplasia in one gland; 2 = nodular hyperplasia in two glands; 3 = nodular hyperplasia in three glands; 4 = nodular hyperplasia in the four glands. For sake of simplicity, the three less severe histological gradings, i.e. scores 0-2 were grouped together and indicated as score group 2. RESULTS: The distribution of the patients was the following: 28.6% were in the score group 2, 23.8% in the score group 3 and 47.6% in the score group 4 (20 patients, 14 of whom were females). The output of the one-way ANOVA with the histological scores as grouping variable and age, dialysis duration, BMI and pre-PTx serum iPTH, alkaline phosphatase (ALP), calcium (Ca) and P as predictors showed that only BMI was different among the three histological scores (P = 0.001). By stratifying the analysis by gender, the relationship between BMI and histological scores was confirmed only in females (P = 0.006). The stratification of the entire cohort into two groups according to the cut-off value of BMI = 25 kg/m(2) showed that: (i) score 4 was more prevalent in the high-BMI group and score 2 in the normal-BMI group (P = 0.01); (ii) female gender was more represented in the high-BMI group (12 out of 18 patients, P = 0.04); and (iii) the pre-PTx serum P levels were significantly higher in the high-BMI group (P = 0.008). The output of the linear multiple regression analysis with pre-PTx serum P as dependent variable and BMI, pre-PTx serum ALP and Ca as independent variables (selected according to the statistical significance in the bivariate correlations) showed that only serum Ca and BMI were statistically significant predictors of serum P levels. CONCLUSIONS: A high BMI and female gender are associated with an increased risk of nodular hyperplasia of parathyroid glands in adult Caucasian haemodialysis patients. The two risk factors, above all if combined in the same patient, appear to predispose to a larger body burden of P, increasing by that way the severity of sHPTH.

Female hemodialysis patients have an increased risk of nodular hyperplasia of parathyroid glands.

BACKGROUND: An association between female gender and more aggressive patterns of secondary hyper-parathyroidism (sHPTH) has been suggested: an increased incidence of refractory sHPTH seems evident in females; therefore, necessitating parathyroidectomy (PTx). METHODS: This study aimed to verify the existence of such an association and secondly to evaluate the impact of female gen-der on parathyroid gland histology. Therefore, a retrospective study was conducted on 67 patients who underwent first PTx (either total or subtotal) in our hospital from 1999-2003. Out of these patients, we selected 55 (28 males, 27 females, mean age 50.8 +/- 14.7 SD yrs, dialysis duration 109.2 +/- 62.4 months) in whom all four parathyroid glands were identified and removed. Serum levels of immunoreactive intact parathyroid hormone (iPTH), alkaline phosphatase, calcium and phosphate were determined at the PTx time point. The same pathologist performed the histological studies of the parathyroid glands on seven serial sections of the glands. Gland hyperplasia was classified as (1) exclusively diffuse (EDH) when only diffuse hyperplasia was found in the four glands; (2) exclusively nodular (ENH) when only nodular hyper-plasia was found in the four glands; (3) diffuse/nodular (D/NH), in which the four glands showed varying degrees of evolution towards both nodular and diffuse hyperplasia. RESULTS: EDH was found in 13 patients with a prevalence of males (11/13; 84.6%); ENH was found in 23 patients with a prevalence of females (15/23; 65.2%); D/NH was found in 19 patients with a similar prevalence between females and males (10 females and 9 males). The difference in the male/female prevalence among the three groups was statistically significant (chi2 test, p=0.015). Serum calcium was significantly higher in the ENH group (one-way analysis of variance, p=0.009). No difference was found among the three groups as far as age, dialysis duration, serum levels of iPTH, alkaline phosphatase and phosphate were concerned. CONCLUSIONS: Female gender is associated with more aggressive histological sHPTH patterns; this association seems to suggest that female gender predisposes to monoclonal proliferation of parathyroid glands in chronic uremia.

Are low plasma levels of 25-(OH)vitamin D a major risk factor for hyperparathyroidism independent of calcitriol in renal transplant patients?

BACKGROUND: Recently, some studies have emphasized the role of plasma 25-(OH)vitamin D (25OHD) levels in mineral metabolism dysregulation in chronic kidney diseases (CKDs). However, to date little attention has been paid to 25OHD metabolism abnormalities after renal transplantation (Tx). This cross-sectional study aimed to focus on its role in mineral metabolism dysregulation in functioning Tx. METHODS: Twenty-eight out of 75 Caucasian Tx patients were selected following strict inclusion and exclusion criteria. Two blood samples were effected at the end of the winter for the measurements of plasma 25OHD and calcitriol levels. Serum creatinine (Cr), alkaline phosphatase (SAP), immunoreactive intact parathyroid hormone (PTH), electrolytes and 24-hr proteinuria were also determined. The Kolmogorov-Smirnov test was used to evaluate the data distribution: serum Cr, Cr clearance, dialysis duration and PTH levels were non-normally distributed and were log-transformed. Values of p<=0.01 were assumed as statistically significant. RESULTS: Median serum Cr and PTH levels were, respectively, 1.0 mg/dL and 90.0 pg/mL (range 27-420; normal range 10-65); most of our Tx patients (78.5%) had serum PTH levels above the upper limit of normal values. Mean plasma 25OHD concentration was 19.6 +/- 8.9 SD ng/mL (range: 6-36). None had levels <5 ng/mL (severe deficiency); 10 patients (35.7%) had mild deficiency (5-15 ng/mL); 14 patients (50%) had vitamin D insufficiency (16-30 ng/mL); and only four patients (14.3%) had target levels (>30 ng/mL). Mean plasma calcitriol levels were 69.7 +/- 19.0 pg/mL (range 47-105; normal range 35-85). They were not significantly correlated to plasma 25OHD levels. Proteinuria (292.6 +/- 147.0 mg/24 hr) inversely correlated to plasma 25OHD levels (r=-0.480; p<0.01). The bivariate correlation analysis between logPTH and the other parameters showed a significant correlation for SAP (r=0.494; p=0.008), plasma 25OHD levels (r=-0.442; p=0.01), proteinuria (r=0.452; p=0.01), log serum Cr (r=0.551; p=0.002) and log Cr clearance (r=-0.534; p=0.003). The other parameters did not correlate significantly with logPTH, notably plasma calcitriol and serum phosphate levels. Only the parameters significantly correlated to logPTH in the bivariate correlation analysis were included in the back stepwise multiple linear regression analysis as independent variables (model: p<0.0001; R2=0.54): among them, only plasma 25OHD levels (Beta=-0.486; p=0.001) and log serum Cr levels (Beta=0.589; p=0.0002) were the dependent variable logPTH predictors. CONCLUSIONS: This cross-sectional study demonstrated that plasma calcitriol levels in a highly selected group of Tx patients were normal and not significantly correlated to either plasma 25OHD or serum PTH levels. Most patients (85.7%) had plasma 25OHD levels below the target value of 30 ng/mL; the latter were inversely correlated with serum PTH levels. Therefore, our study strengthens the suggestion that low plasma 25OHD levels are a major risk factor for secondary hyperparathyroidism (sHPTH) in Tx patients and stresses the importance of monitoring these patients.