Aurelio Negro

High prevalence of primary aldosteronism using postcaptopril plasma aldosterone to renin ratio as a screening test among italian hypertensives

The prevalence of primary aldosteronism (PA) was assessed in a specialized hypertension center. Baseline and postcaptopril (50 mg orally) aldosterone to plasma renin activity ratio (A/R) as a screening tool were preliminarily tested in a sample including 22 patients with histories of PA and 53 patients with low-renin essential hypertension (EH). Sensitivity and specificity of A/R > or =35 were 95.4% and 28.3% at baseline, compared with 100% and 67.9% after captopril. Using postcaptopril A/R > or =35 and confirmation by acute saline loading, a PA prevalence of 6.3% was found among 1046 consecutive hypertensive patients with normal renal function. Of those 66 PA patients, 16 (24.2%) had a unilateral adenoma, whereas 50 (75.8%) had idiopathic hyperaldosteronism. At presentation, 45.4% of the PA and 16.3% of EH patients were treated with two or more antihypertensive drugs (chi(2) = 33.117, P <.0001). However, among untreated patients (n = 553), the prevalence of mild-to-moderate hypertension (ie, <180/110 mm Hg) was not different between patients with PA and those with EH (70.6% v 76.7%, chi(2) = 0.086, P =.770). Serum potassium > or =3.6 mEq/L was found in 60.6% of PA patients. In conclusion, we observed the following: 1) postcaptopril compared with baseline A/R is a better screening tool for PA; 2) PA is relatively frequent among hypertensive individuals; 3) PA is not necessarily associated with severe hypertension; and 4) hypokalemia is an insensitive screening criterion for PA.

Alterations of calcium metabolism and of parathyroid function in primary aldosteronism, and their reversal by spironolactone or by surgical removal of aldosterone-producing adenomas

In order to investigate the possible existence of abnormal calcium metabolism and parathyroid function in primary aldosteronism (PA), we have compared the calcium/parathyroid hormone (PTH) profile of patients with PA with the profile of healthy normotensive subjects and of patients with essential hypertension (EH). Furthermore, we have evaluated the effects of spironolactone and the surgical removal of aldosterone-producing adenomas on the calcium/PTH profile in the PA patients. Four groups of 10 subjects each participated in the study: 1) hypertensive patients with PA, 2) patients with low-renin EH (LREH), 3) patients with normal-renin EH (NREH), 4) normotensive healthy subjects (NS). The four groups were well-matched for age, sex, body mass index, and renal function. The three hypertensive groups were also matched closely for blood pressure values and for duration of hypertension. In all subjects, after 1 week of a controlled intake of Na and K, the following parameters were measured: urine excretion of Na, K, Ca, Mg, and P, plasma levels of K, Mg, inorganic P, total calcium and ionized calcium, and plasma renin activity, aldosterone concentration, and intact PTH. Blood pressure and laboratory parameters were determined again in all the PA patients after 1 month of 100 mg daily spironolactone administration, and in four out of the 10 PA patients 2 months after surgical removal of aldosterone-producing adenomas. All of these subjects had undergone the same controlled intake of Na and K indicated above. Serum intact PTH was higher in PA patients than in the other three groups (P < .01), and serum ionized calcium was significantly higher in normotensive subjects than in the three hypertensive groups (v PA P < .01, v LREH and v NREH P < .05). An increase in serum ionized calcium and a decrease in PTH level were associated with both spironolactone administration (P < .001) and surgical treatment (P < .05). These results suggest the presence of calcium metabolism alterations in both PA and EH patients, but that these alterations are more exaggerated in PA, so that higher PTH levels are needed for maintaining low-normal levels of serum ionized calcium.

Elevation of Angiotensin-II Type-1-Receptor Autoantibodies Titer in Primary Aldosteronism as a Result of Aldosterone-Producing Adenoma

The mechanisms of excess aldosterone secretion in primary aldosteronism (PA) remain poorly understood, although a role for circulating factors has been hypothesized for decades. Agonistic autoantibodies against type-1 angiotensin-II receptor (AT1AA) are detectable in malignant hypertension and preeclampsia and might play a role in PA. Moreover, if they were elevated in aldosterone-producing adenoma (APA) and not in idiopathic hyperaldosteronism (IHA), they might be useful for discriminating between these conditions. To test these hypotheses, we measured the titer of AT1AA in serum of 46 patients with PA (26 with APA, 20 with IHA), 62 with primary hypertension (PH), 13 preeclamptic women, and 45 healthy normotensive blood donors.We found that the AT1AA titer was higher (P<0.05) in both PA and PH patients (2.65±1.55 and 1.86±0.63, respectively) than in normotensive subjects (1.00±0.20). In APA, it was 2-fold higher than in IHA patients (3.43±1.20 versus 1.64±1.39, respectively, P<0.001), despite similar blood pressure values. Of note, it allowed effective discrimination of APA from either PH or IHA, as shown by Receiver Operator Characteristics curve analysis. Moreover, after captopril challenge, plasma aldosterone concentration fell more in AT1AA-positive than in AT1AA-negative PA patients (–32.4% [21.1–42.9] versus 0.0% [0.0–22.6], P=0.015), suggesting an agonistic role for these autoantibodies. Thus, a higher serum AT1AA titer in patients with APA than in IHA and PH patients can be useful in differentiating APA patients from either PH or IHA, and thus in selecting PA patients to be submitted to adrenal vein sampling.

Increased plasma levels of platelet-derived growth factor (PDGF-BB + PDGF-AB) in patients with never-treated mild essential hypertension

Platelet-derived growth factor (PDGF) could play a role in both vascular hypertrophy and atherosclerotic disease associated with hypertension. To assess whether plasma PDGF level is increased in mild essential hypertension, we measured plasma PDGF concentration in 25 never-treated patients with uncomplicated mild essential hypertension and in 22 normotensive healthy subjects. To evaluate the contribution of platelets to plasma PDGF in the two groups, we also measured plasma beta-thromboglobulin (BTG). Measurement of PDGF was carried out through an enzyme-linked immunoadsorbent assay, which detects two PDGF dimers, namely PDGF-BB and PDGF-AB. Both plasma PDGF and BTG were higher in the hypertensive than in the normotensive subjects. The ratio of PDGF to BTG was similar in the two groups. Plasma PDGF was weakly correlated with plasma BTG in the normotensive subjects, whereas this relationship was lost in the hypertensive patients. Our results suggest that the increase in plasma PDGF (PDGF-AB + PDGF-BB) in never-treated essential hypertension is mainly due to platelet activation. The increased circulating level of PDGF could play a role in the vascular structural changes associated with hypertension.

Intraprocedural cortisol measurement increases adrenal vein sampling success rate in primary aldosteronism.

BACKGROUND Adrenal venous sampling (AVS) is the gold standard for the identification of unilateral primary aldosteronism (PA), but is technically difficult. The aim of our study was to assess whether intraprocedural cortisol measurement (IPCM) increases AVS success rate. METHODS Twenty-five consecutive PA patients underwent cosyntropin-stimulated AVS. Cortisol was measured immediately in a first set of samples drawn from adrenal veins and inferior vena cava. The selectivity criterion was an adrenal vein-to-inferior vena cava cortisol ratio ≥5. If bilateral selectivity was not achieved in a first set of samples, a second set was obtained during the same radiological session. PA was judged as unilateral if the gradient of cortisol-corrected aldosterone between dominant and nondominant side was >3.5. Twenty-five consecutive PA patients who had previously been submitted to AVS without IPCM served as historical controls. Lateralizing patients who underwent unilateral adrenalectomy were followed for 2 years after surgery. RESULTS Bilateral selectivity using IPCM was achieved in 19/25 patients in the first set of samples, and in an additional four cases in the second set (92% vs. 76%; P = 0.06). The final rate of bilateral selectivity was higher than that obtained in the historical series (23/25 vs. 16/25, P = 0.04), whereas bilateral selectivity in the first set of samples was not different from that achieved in the historical series. Nineteen lateralizing patients (13 of the present series, six of the historical series) were submitted to adrenalectomy, resulting in reversal of PA. CONCLUSIONS IPCM increases the success rate of AVS.

Heart Rate Variability in Patients with Sjögren’s Syndrome

Abstract: Heart rate variability (HRV) gives information about sympathetic–parasympathetic autonomic balance. Our purpose was to determine whether HRV is abnormal in patients with Sjögren’s syndrome. In 16 patients with Sjögren’s syndrome and 30 matched controls, a short time analysis of HRV was performed for both the frequency and the time domain. In the time domain, patients tended to display a slower heart rate, greater R-R variability and higher standard deviation of the mean (SDNN) than did healthy subjects, but the differences were not statistically significant. In the frequency domain the spectral measures of HRV showed a slight reduction of LF and an increase of HF; as a result, the ratio between high and low frequencies, representative of sympathovagal modulation, was significantly reduced. Our data suggest an increase in the parasympathetic control of heart rate in patients with Sjögren’s syndrome. This predominance in vagal tone could exert a protective and antiarrhythmic role in patients with primary Sjögren’s syndrome, and may be relevant with reference to the lower incidence of sudden death in this disorder compared to other major autoimmune diseases.

Liddle's syndrome caused by a novel missense mutation (p617l) of the epithelial sodium channel β subunit

Objective The aim of the study was to search for mutations of SCNN1B and SCNN1G in an Italian family with apparently dominant autosomal transmission of a clinical phenotype consistent with Liddles syndrome. Methods Genetic analysis was performed in the proband, his relatives, and 100 control subjects. To determine the functional role of the mutation identified in the proband, we expressed the mutant or wild-type epithelial sodium channel in Xenopus laevis oocytes. Results A novel point mutation, causing an expected substitution of a leucine residue for the second proline residue of the conserved PY motif (PPP × Y) of the β subunit was identified in the proband. The functional expression of the mutant epithelial sodium channel in X. laevis oocytes showed a three-fold increase in the amiloride-sensitive current as compared with that of the wild-type channel. Conclusion This newly identified mutation adds to other missense mutations of the PY motif of the β subunit of the epithelial sodium channel, thus confirming its crucial role in the regulation of the epithelial sodium channel. To our knowledge, this is the first report of Liddles syndrome in the Italian population, confirmed by genetic and functional analysis, with the identification of a gain-of-function mutation not previously reported.

−344C/T polymorphism of CYP11B2 gene in Italian patients with idiopathic low renin hypertension

Most patients with low renin essential hypertension are not qualitatively different from patients with idiopathic hyperaldosteronism, as in both conditions aldosterone secretion is not appropriately reduced. The aim of the study was to investigate allele and genotype frequencies of the -344C/T polymorphism, located in the promoter region of the aldosterone synthase gene, in 83 patients with idiopathic low renin hypertension characterized by an increased aldosterone to renin ratio, including both patients with low renin essential hypertension (n=53) and subjects with idiopathic hyperaldosteronism (n=30), compared with 78 patients with normal to high renin essential hypertension and 126 normotensive control subjects. The relationship of -344C/T genotypes to basal and postcaptopril plasma aldosterone/plasma renin activity ratio was also examined in the entire hypertensive population. An increased frequency of the T allele and a relative excess of TT homozygosity over CC homozygosity were found in patients with idiopathic low renin hypertension in comparison with both normal to high renin hypertensives and normotensive controls. A higher post-captopril aldosterone to renin ratio was found in the hypertensives with TT genotype than in those with CC genotype, and TT+TC genotypes were associated with a smaller decrease in the aldosterone-to-renin ratio elicited by captopril administration. The present study suggests that the -344C/T polymorphism, or a functional variant in linkage disequilibrium with it, may play a role in the abnormal regulation of aldosterone secretion in idiopathic low renin hypertension.

A Clinical phenotype mimicking essential hypertension in a newly discovered family with liddle's syndrome

BACKGROUND Liddles syndrome (LS) is a monogenic form of hypertension simulating a mineralocorticoid excess, and is currently suspected in young hypokalemic hypertensives. The aims of the study were: (i) to evaluate the clinical phenotype of LS in a newly identified Italian family of Sicilian origin carrying a gain-of-function mutation of the β subunit of the epithelial sodium channel (ENaC) (P617L) previously reported by our group in an apparently unrelated Sicilian patient presenting the typical phenotype of LS including hypokalemia; (ii) to determine whether an unknown biological relationship exists between the newly identified family and the family of the proband previously reported. METHODS Genetic analysis was performed in the present family, in the individual in which the βP617L mutation was first observed, and in his relatives. RESULTS βP617L mutation was identified in the proband and in three maternal relatives. None of them showed hypokalemia. Mild to severe early onset hypertension and left ventricular hypertrophy were present in all of them. Analysis of mitochondrial DNA (mtDNA) and Y chromosome profiles in the present family and in the probands family previously reported showed the absence of a relationship between them. The availability of only one carrier of the mutation in one of the two families meant that a genetic analysis able to assess a founder effect was not feasible. CONCLUSIONS LS should be considered in all cases of early onset hypertension, independently of the plasma potassium concentration. The incidence of LS may be greater than is currently thought, because hypokalemia is not invariably present.

Oxaliplatin-induced proximal renal tubular acidosis

Oxaliplatin is a third generation platinum compound, effectively used in the treatment of advanced colon cancer, especially in combination with 5-fluorouracil. Unlike other platinum derivates, no significant nephrotoxicity has been reported [1]. However, some studies with oxaliplatin identify acute tubular necrosis [2] and a case of proximal renal tubular acidosis (pRTA) during Fanconi’s syndrome [3]. We report on a case of severe oxaliplatin-induced pRTA in a 66-year-old man with colon cancer. Adenocarcinoma of the left colon (pT4N0M0, stage II) was diagnosed following hemicolectomy and ureteroileostomy. Routine blood tests and urinalysis yielded normal results. The patient started adjuvant chemotherapy with 5-fluorouracil and oxaliplatin (140 mg/m every 21 days). Plasma bicarbonate values, available only after the second cycle of chemotherapy, were normal. After six cycles (cumulative dose of oxaliplatin 980 mg), the patient was admitted because of a 10-day history of anxiety, lethargy, headache and altered mental status. At presentation, he was moderately febrile and dehydrated; he denied diarrhea or laxative abuse. A Chest X-ray study was unremarkable. Laboratory findings are shown in Table 1. They indicate a severe hypokalemic, hyperchloremic metabolic acidosis with a normal anion gap. Chemotherapy was stopped. First intravenous then oral alkali therapy led to a normalization of plasma pH and bicarbonate levels. After 6 months, with no alkali therapy, the serum pH was 7.41 and serum bicarbonate was 23 mmol/l. pRTA is characterized by renal bicarbonate wasting and low plasma bicarbonate levels. It may present as an isolated defect or in the setting of a complex proximal tubular dysfunction called Fanconi’s syndrome, which features bicarbonaturia, glycosuria, phosphaturia, uricosuria, aminoaciduria and tubular proteinuria. Unlike the case reported by Linch et al. [3], our patient showed no overt Fanconi’s syndrome, but only bicarbonate wasting and severe hypokalemic, hyperchloremic metabolic acidosis with a normal anion gap, thus suggesting isolated pRTA. In pRTA, the urinary pH can be\6 because distal urinary acidification is not impaired. In our patient, the moderately elevated urinary pH, despite normal renal NH4 ? production, was probably due to concurrent urinary tract infection by a urea-splitting organism (Proteus mirabilis). We acknowledge that, in this case, the ureteral diversion was expected to determine metabolic acidosis by itself; however, significant hyperchloremic metabolic acidosis is more commonly reported, and is usually more severe in patients with ureterosigmoidostomy, because the contact time between the urine and intestine in an ileal conduit is too short and not sufficient to cause any significant changes in urinary composition to occur [4]. The basis of nephrotoxicity of platinum agents are not well known. However, recently it is proposed that nephrotoxicity of platinum derivates should be determined by renal accumulation via an imbalance between organic cation transporters localized on basolateral membranes of the proximal renal tubules, and multidrug and toxin extrusion family expressed in the brush-border membrane of proximal tubules [5]. Conceivably, individual variation in the activity of these transporters family may cause adverse effects on renal function. A. Negro (&) C. Grasselli P. Galli Second Unit of Internal Medicine, Department of Internal Medicine, Santa Maria Nuova Hospital, viale Risorgimento, 80, 42100 Reggio Emilia, Italy e-mail: negro.aurelio@asmn.re.it