High frequency and founder effect of the CYP3A4*20 loss-of-function allele in the Spanish population classifies CYP3A4 as a polymorphic enzyme.

Cytochrome P450 3A4 (CYP3A4) is a key drug-metabolizing enzyme. Loss-of-function variants have been reported as rare events, and the first demonstration of a CYP3A4 protein lacking functional activity is caused by CYP3A4*20 allele. Here we characterized the world distribution and origin of CYP3A4*20 mutation. CYP3A4*20 was determined in more than 4000 individuals representing different populations, and haplotype analysis was performed using CYP3A polymorphisms and microsatellite markers. CYP3A4*20 allele was present in 1.2% of the Spanish population (up to 3.8% in specific regions), and all CYP3A4*20 carriers had a common haplotype. This is compatible with a Spanish founder effect and classifies CYP3A4 as a polymorphic enzyme. This constitutes the first description of a CYP3A4 loss-of-function variant with high frequency in a population. CYP3A4*20 results together with the key role of CYP3A4 in drug metabolism support screening for rare CYP3A4 functional alleles among subjects with adverse drug events in certain populations.

Rare diseases in clinical endocrinology: a taxonomic classification system.

PURPOSE: Rare endocrine-metabolic diseases (REMD) represent an important area in the field of medicine and pharmacology. The rare diseases of interest to endocrinologists involve all fields of endocrinology, including rare diseases of the pituitary, thyroid and adrenal glands, paraganglia, ovary and testis, disorders of bone and mineral metabolism, energy and lipid metabolism, water metabolism, and syndromes with possible involvement of multiple endocrine glands, and neuroendocrine tumors. Taking advantage of the constitution of a study group on REMD within the Italian Society of Endocrinology, consisting of basic and clinical scientists, a document on the taxonomy of REMD has been produced. METHODS AND RESULTS: This document has been designed to include mainly REMD manifesting or persisting into adulthood. The taxonomy of REMD of the adult comprises a total of 166 main disorders, 338 including all variants and subtypes, described into 11 tables. CONCLUSIONS: This report provides a complete taxonomy to classify REMD of the adult. In the future, the creation of registries of rare endocrine diseases to collect data on cohorts of patients and the development of common and standardized diagnostic and therapeutic pathways for each rare endocrine disease is advisable. This will help planning and performing intervention studies in larger groups of patients to prove the efficacy, effectiveness, and safety of a specific treatment.

Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE in individuals with neck or mediastinal paraganglioma (PGL).

Paragangliomas (PGLs) are neuroendocrine tum-ors that arise embryologically from the neural crest. Sympathetic PGLs can be located in the thoracic-abdominal region while parasympathetic PGLs are mainly situated in the head and neck region. Most PGLs are sporadic, but in 30% of cases they are hereditary (associated with mutations of SDHB, SDHC, SDHD, SDHAF2, SDHA, TMEM, MAX, and VHL); they can be classified into 4 different paraganglioma syndromes: PGL1, PGL2, PGL3, and PGL4. Surgery is the treatment of choice for both sympathetic and parasympathetic PGLs. Other types of treatment include medical agents (such as gemcitabine, cisplatin, or sunitinib) and radiotherapy (external-beam radiotherapy or stereotactic surgery). Surgery and radiotherapy, however, can cause important side effects such as vascular complications and peripheral nerve damage (hypoglossal, recurrent laryngeal, glossopharyngeal, and vagus). Another possible treatment option is the use of peptide receptor radionuclide therapy (PRRT), including PRRT with 177Lu-DOTATATE. We studied 4 patients with hereditary nonmetastatic paraganglioma syndrome type 1 (PGL1), with progressive disease, in whom surgical excision was not possible. They were treated with 177Lu-DOTATATE (3-5 cycles) and all had a partial response (PR) or a stable disease (SD) to the treatment. In conclusion, a good alternative treatment when surgical or radiation therapy are contraindicated could be radiometabolic therapy with 177Lu-DOTATATE.

Genetics of adrenal tumors.

The impact of genetics and genomics on clinical medicine is becoming more and more important. Endocrinology pioneered the development of molecular medicine, but also the study of adrenal tumors had a great impact in this field. Particularly important was the detection of genetics of tumors derived from the adrenal medulla, as well as that of those derived from the sympathetic and parasympathetic paraganglia. The identification of mutations in one of the several pheochromocytoma/paraganglioma susceptibility genes may indicate a specific clinical management drive. Less well understood is the genetics of adrenal cortex tumors, in particular adrenocortical carcinoma, a rare and particularly aggressive disease. There are only a few examples of hereditary transmission of adrenocortical carcinoma, but the analysis of low penetrance genes by genome wide association study may enable us to discover new genetic mechanisms responsible for adrenocortical-derived tumors.

Role of the genetic study in the management of carotid body tumor in paraganglioma syndrome.

Diagnosis of carotid body tumor (CBT) was made in a 36 years old woman. The pre-operative examination included genetic analysis of the succinate dehydrogenase that showed a mutation in his subunit D responsible of multiple paraganglioma at slow growth. Subsequently a thoraco-abdominal CT and indium(111) octreotide body scan were performed and another paraganglioma was detected in the anterior mediastinum. CBT was surgically removed; differently the thoracic lesion due to his benign genetic profile was not treated. During a 3-years follow-up the thoracic paraganglioma as expected, didn't increase. Genetic analysis of succinate dehydrogenase, should be performed in the management of CBT.

Neurosurgical treatment of von Hippel-Lindau-associated hemangioblastomas: benefits, risks and outcome.

AIM: Von Hippel-Lindau (VHL) disease is a genetic syndrome predisposing to central nervous system (CNS) hemangioblastomas and several lesions in many organs. The cases of all VHL individuals operated on in the Neurosurgical Unit of Padua Hospital since year 2000 were reviewed in order to define which features lead to surgical treatment and to examine surgical outcome during postoperative follow-up. METHODS: The authors evaluated 20 VHL subjects (7 males and 13 females, age at surgery 32+/-10 years) who underwent 28 operations in order to remove 48 CNS hemangioblastomas and 1 endolymphatic sac tumor. Among the 49 resected lesions, 21 (42%) were cerebellar, 9 (18%) at brainstem, 19 (38%) spinal (7 cervical, 6 dorsal, 6 at cone-cauda level), and 1 (2%) endolymphatic sac tumor in the petrous bone. Patients were graduated according to Karnofsky Performance Status (KPS) at admission, at discharge and during the last follow up visit. Genetic testing revealing the presence of a VHL disease-causing mutation was a prerequisite for inclusion in the study. RESULTS: Nineteen individuals (95%) were symptomatic. Symptomatic hemangioblastomas were associated with a cyst or a syrinx in 22/27 circumstances (81%). Total removal, as confirmed by postoperative magnetic resonance imaging (MRI), was achieved in all but one lesion. Following surgery, at follow-up (38+/-20 months), patients improved their neurological status in 75% of cases, 20% remained stable and 5% worsened; 16 patients (80%) are able to carry on normal activity with or without minor symptoms, 3 patients require some grade of assistance, 1 patient died because of bronchopneumonia. CONCLUSION: VHL-associated hemangioblastomas generally affect a young adult population and can be successfully removed, either when symptomatic, or when they reach a critical volume. Microsurgery of hemangioblastomas has a favourable impact on survival and quality of life of VHL patients, although it is strongly influenced by preoperative conditions. Transient surgical complications are possible, particularly with brainstem and spinal cord hemangioblastomas.

Genetics and biology of pheochromocytoma.

The familial forms of pheochromocytoma have recently been demonstrated to be more frequent than believed in the past. The genes currently known to be responsible for tumor formation are RET, VHL, NF1, SDHB, SDHC and SDHD. Germline mutations of these genes increase the risk of developing pheochromocytomas and/or paragangliomas which variably associate with other neoplasms and characterize diverse clinical syndromes such as MEN 2, von Hippel-Lindau (VHL), and neurofibromatosis type 1 (NF 1), or the PGL syndromes, respectively. Although the pathogenesis of pheochromocytoma/paraganglioma formation is still largely unknown, studies of the familial forms have started to uncover some pathways that favor tumor formation, such as activation of tyrosine-kinase, induction of hypoxia-inducible factors, activation of the oncogene Ras or reduced apoptosis. These studies have also demonstrated that various gene mutations can differently affect the biological characteristics of pheochromocytoma: for example, while the tumors are mostly adrenergic (epinephrine secreting) and episodically secreting in MEN 2, they are mostly noradrenergic (norepinephrine secreting) and continuously secreting in VHL. Biological variability can also be observed in the PGL syndromes where tumors develop in the head and neck and are parasympathetic in origin and non-secreting, or in the thorax and the abdomen, where they are sympathetic in origin and catecholamine secreting. Genetic testing in patients with pheochromocytomas or paragangliomas is, at present, strongly recommended and is mandatory in young patients or in cases of multiple or recurrent tumors. The clinical picture and the biological characteristics of the tumor may suggest the priority of the genes to be tested first.

Endolymphatic sac tumour in von Hippel-Lindau disease: management strategies.

Endolymphatic sac tumour (ELST) is infrequent, as emerges from small series reported in the literature. It is a slow-growing malignancy with local aggressiveness and a low risk of distant metastases. It is often misdiagnosed because of the late onset of symptoms and difficulty in obtaining a biopsy. Its frequency is higher in von Hippel-Lindau (VHL) disease (a genetic systemic syndrome involving multiple tumours), with a prevalence of around 25%. The diagnosis is based on radiology, with specific patterns on contrast-enhanced MRI and typical petrous bone erosion on bone CT scan. Our experience of ELST in the years between 2012-2015 concerns 7 cases, one of which was bilateral, in patients with VHL disease. Four of the 7 patients underwent 5 surgical procedures at our institution. Each case is described in detail, including clinical symptoms, and the intervals between symptom onset, diagnosis and therapy. Postoperative morbidity was low after early surgery on small tumours, whereas extensive surgery for large tumours was associated with loss of cranial nerve function (especially VII, IX, X). The critical sites coinciding with loss of neurological function were the fallopian canal, jugular foramen, petrous apex and intradural extension into the posterior cranial fossa. Early surgery on small ELST is advocated for patients with VHL disease, in whom screening enables a prompt diagnosis and consequently good prognosis.

A meta-iodobenzylguanidine scintigraphic scoring system increases accuracy in the diagnostic management of pheochromocytoma.

As observed by other authors, normal adrenal medullary tissue frequently gives an apparently positive meta-iodobenzylguanidine (MIBG) scan in cases studied using 123I-MIBG and less frequently 131I-MIBG. The aim of this study was to assess the usefulness of a scoring system, based on different uptakes of the radiopharmaceutical, to improve the accuracy of 123I-MIBG scintigraphy in patients with either adrenal or extra-adrenal pheochromocytomas. Charts from 67 consecutive patients (29 males and 38 females, median age 48 years, range 14-80 years) with suspected pheochromocytoma (either sporadic or familial: multiple endocrine neoplasia (MEN) 2a, MEN2b, Von Hippel-Lindau, neurofibromatosis type 1) who underwent 123I-MIBG scintigraphy (scans acquired 4-24 h after injection) from 1991 to 2004, were independently reviewed by two experienced nuclear medicine physicians using liver uptake as a reference (scores: 1, uptake absent or less than the liver; 2, equal to the liver; 3, moderately more intense than the liver; 4, markedly more intense than the liver). Interfering medications were discontinued for the appropriate time before MIBG injection. Histological data were obtained for all patients who underwent adrenalectomy. Scintigraphies were classified as positive using the following criteria: extra-adrenal focal uptake, adrenal enlargement together with non-homogeneous uptake and adrenal uptake more intense than the liver (score 3-4). After surgical resection, as confirmed by histological findings and long-term follow-up (range 1-14 years, average 9.25 years), 43 patients were considered true positives using the proposed scoring system, 20 were true negatives, four were false negatives and none was false positive. In conclusion, the proposed scoring system demonstrated high specificity (100%), sensitivity (91.5%) and accuracy (94%) in the management of pheochromocytoma. Positive predictive value and negative predictive value were 100% and 83.3% respectively. Normal adrenal tissue uptake was correctly discriminated from pheochromocytomas in 18 out of 20 patients, with adrenal uptake equal to the liver (grade 2), using the proposed cut-off level.

ARMC5 mutation analysis in patients with primary aldosteronism and bilateral adrenal lesions.

Idiopathic hyperaldosteronism (IHA) due to bilateral adrenal hyperplasia is the most common subtype of primary aldosteronism (PA). The pathogenesis of IHA is still unknown, but the bilateral disease suggests a potential predisposing genetic alteration. Heterozygous germline mutations of armadillo repeat containing 5 (ARMC5) have been shown to be associated with hypercortisolism due to sporadic primary bilateral macronodular adrenal hyperplasia and are also observed in African-American PA patients. We investigated the presence of germline ARMC5 mutations in a group of PA patients who had bilateral computed tomography-detectable adrenal alterations. We sequenced the entire coding region of ARMC5 and all intron/exon boundaries in 39 patients (37 Caucasians and 2 black Africans) with confirmed PA (8 unilateral, 27 bilateral and 4 undetermined subtype) and bilateral adrenal lesions. We identified 11 common variants, 5 rare variants with a minor allele frequency <1% and 2 new variants not previously reported in public databases. We did not detect by in silico analysis any ARMC5 sequence variations that were predicted to alter protein function. In conclusion, ARMC5 mutations are not present in a fairly large series of Caucasian patients with PA associated to bilateral adrenal disease. Further studies are required to definitively clarify the role of ARMC5 in the pathogenesis of adrenal nodules and aldosterone excess in patients with PA.

Role of atrial natriuretic peptide in the pathogenesis of sodium retention in IDDM with and without glomerular hyperfiltration.

The pathogenetic determinants of sodium retention in IDDM are not fully understood. The aim of this study was to elucidate the action of ANP in 11 IDDM patients with high GFR (greater than or equal to 135 ml.min-1 x 1.73 m-2), referred to here as HF patients; in 10 IDDM patients with normal GFR (greater than 90 and less than 135 ml.min-1 x 1.73 m-2), referred to here as NF patients; and 12 control subjects, here called C subjects, at baseline and during saline infusion administered on the basis of either body weight (2 mmol.kg-1 x 60 min-1; Saline 1) or of ECV (12 mM.ECVL-1 x 90 min-1; Saline 2) during euglycemic insulin-glucose clamp. C subjects and both HF and NF IDDM patients received a second Saline 1 infusion accompanied by ANP infusion (0.02 microgram.kg-1.min-1) at euglycemic levels. HF and NF patients were studied again after 3 mo of treatment with (10 mg/day). Quinapril (CI 906, Malesci, Florence, Italy), an ACE inhibitor without sulfhydryl group. At baseline, both HF and NF IDDM patients had higher plasma ANP concentrations than C subjects (HF, 36 +/- 4, P less than 0.01 and NF, 34 +/- 3, P less than 0.01 vs. C, 19 +/- 3 pg/ml). Plasma ANP and natriuretic response to isotonic volume expansion was impaired both in HF (44 +/- 8 pg/ml, NS vs. base) and NF (40 +/- 7 pg/ml, NS vs. base) compared with C (41 +/- 4 pg/ml, P less than 0.01 vs. base) during Saline 1. On the contrary, plasma ANP response to Saline 2 was similar in HF and NF patients and C subjects, but IDDM patients had still lower urinary sodium excretion rates. The simultaneous administration of ANP and Saline 1 resulted in comparable plasma ANP plateaus in C subjects and HF and NF patients. However, urinary sodium excretion rate was significantly lower in HF and NF patients than in C subjects: HF, 267 +/- 64, P less than 0.01 and NF, 281 +/- 42, P less than 0.01 vs. C, 424 +/- 39 mumol.min-1 x 1.73 m-2. During simultaneous administration of ANP and Saline 1, GFR and FF increased in C subjects, but not in HF and NF patients. HF and NF patients had higher urinary vasodilatory prostanoid excretion rates than C subjects at baseline. Saline infusion did not change urinary excretion rate of prostanoids either in C subjects or IDDM patients (both NF and HF).(ABSTRACT TRUNCATED AT 400 WORDS)

Role of insulin and atrial natriuretic peptide in sodium retention in insulin-treated IDDM patients during isotonic volume expansion.

Because insulin shows an antinatriuretic effect in healthy humans, insulin therapy resulting in circulating hyperinsulinemia may lead to sodium retention and in turn to hypertension in individuals with insulin-dependent diabetes mellitus (IDDM). Moreover, it has been proved that atrial natriuretic peptide (ANP) plays a major role in modulating natriuresis in humans. This study investigated the relationship between insulin and ANP in modulating sodium metabolism in normotensive and hypertensive IDDM subjects compared with control groups of normotensive and hypertensive nondiabetic subjects. IDDM normotensive and hypertensive subjects had mean +/- SE duration of IDDM of 7 +/- 2 and 8 +/- 2 yr, respectively, and had no clinical features of diabetic nephropathy. All subjects received a saline infusion (2 mmol.kg-1.90 min-1) during euglycemia. IDDM normotensive and hypertensive subjects received a subcutaneous insulin infusion (15 mU.kg-1.h-1), resulting in twofold higher plasma free-insulin levels (16 +/- 2 and 19 +/- 3 microU/ml, respectively) than in nondiabetic normotensive and hypertensive subjects (7 +/- 2 and 8 +/- 2 microU/ml, respectively). During saline challenge, sodium excretion increased by 22 +/- 4% in normotensive and 49 +/- 9% in hypertensive nondiabetic subjects but by only 11 +/- 0.4% in normotensive (P less than 0.01) and 8 +/- 2% in hypertensive (P less than 0.01) IDDM subjects. The impaired natriuretic response to saline challenge was mainly due to greater rates of sodium reabsorption by kidney proximal tubules in IDDM than nondiabetic subjects. At baseline, plasma ANP concentrations were significantly higher in both IDDM groups than in control groups (normotensive IDDM and control subjects: 38 +/- 4 and 19 +/- 2 pg/ml, respectively, P less than 0.01; hypertensive IDDM and control subjects: 45 +/- 6 and 27 +/- 4 pg/ml, respectively, P less than 0.05). After saline challenge, ANP concentrations rose to 39 +/- 4 pg/ml in normotensive and 49 +/- 5 pg/ml in hypertensive control subjects, whereas no significant change above baseline value was seen in IDDM subjects. Both IDDM groups showed a 10-12% greater exchangeable Na+ pool than control subjects regardless of the presence of hypertension. Subcutaneous insulin infusion, resulting in circulating plasma free-insulin levels in normotensive control subjects comparable to those in IDDM patients, inhibited natriuresis, increased proximal tubule sodium reabsorption at the level of the kidney, and inhibited an adequate ANP stimulation by saline challenge. We conclude that hyperinsulinemia leads to increased proximal tubule sodium reabsorption and impaired ANP response during saline administration. Both mechanisms account for sodium retention in normotensive and hypertensive IDDM patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Somatic mosaicism in von Hippel-Lindau Disease.

von Hippel-Lindau (VHL) disease is an autosomal dominant familial cancer syndrome predisposing to the development of retinal and central nervous system haemangioblastomas, pheochromocytomas, renal and pancreatic cancer. In the course of a molecular analysis conducted to detect germline mutations of this gene in von Hippel-Lindau patients and individuals affected by sporadic tumors, we have identified a case of somatic mosaicism in the asymptomatic mother of a VHL patient who was subsequently diagnosed with pheochromocytoma. This is the first report providing molecular evidence of somatic mosaicism in von Hippel-Lindau disease. Mosaicism could provide some genetic explanation for the clinical heterogeneity and variable severity of the VHL phenotype, and should be considered, as a possible event when evaluating sporadic cases of VHL or patients with isolated VHL-related tumors. Hum Mutat 15:114, 2000.

Sodium regulating hormones at high altitude: basal and post-exercise levels.

High altitude (HA)-induced diuresis is associated with marked changes in sodium and water regulating hormones, particularly the renin-angiotensin-aldosterone system (RAAS) and atrial natriuretic hormone (ANH). These hormones are also strongly stimulated by physical exercise, which is a major component of daily activity at HA. In spite of the numerous studies in literature, a clear relationship between hormonal changes, HA diuresis, and physical exercise has not yet been established. We therefore evaluated the response of sodium regulating hormones to exhaustive exercise in a group of seven males exposed to prolonged HA hypoxia. The study was divided into four phases: sea level (SL1), after 7 (P1) and after 21 (P2) days at 5050 m (Italian National Research Council Pyramid Laboratory, Nepal), and back at sea level (SL2). At each phase plasma hematocrit (Ht), total body water (TBW), 24-hr sodium excretion (uNa), and urinary volume (uV) were evaluated together with PRA, plasma aldosterone, and ANH, in samples drawn basally from patients in upright position, and at the end of graded step-wise (30 W/2 min) maximal exercise. Levels of uNa and uV were raised at P1 and then declined at P2, with a parallel decrease in TBW and an increase in Ht. Basal PRA and aldosterone levels were suppressed both at P1 and P2 (from 1.9 +/- 0.4 to 0.08 +/- 0.03 and 0.5 +/- 0.1 ng/mL/3 h, and from 7.9 +/- 1.8 to 3.9 +/- 0.4 and 4.5 +/- 0.4 ng/dL, respectively; P < .05). Exhaustive exercise at HA did not induce any significant response in PRA and aldosterone, unlike SL1. Otherwise at P1 ANH levels remained unchanged both basally and during exercise, while at P2 they decreased significantly vs. SL1, both basally and after exercise (from 13.3 +/- 5.7 to 3.5 +/- 1.2 and from 40.2 +/- 10.2 to 17.5 +/- 8.3, respectively; P < .05). Our data show that PRA and aldosterone levels were constantly suppressed at HA and were unresponsive to exercise, whereas the ANH response was significantly stimulated during acute HA exposure, but not during chronic exposure. This suggests that hypoxia-induced chemoreceptor stimulation may cause the natriuretic phenomenon through direct suppression of the RAAS.

Angiotensin II receptors in cortical and medullary adrenal tumors.

Several pieces of evidences suggest that angiotensin II (Ang II) has mitogenic effects, and a link between Ang II receptors and adrenal tumors can be suggested. In various adrenal tumors, aldosterone-producing adenoma (APA), Cushing's adrenal adenomas (Cush), pheochromocytomas (Pheo), and adrenal carcinomas, we studied the density, affinity, and subtype of Ang II receptors. Ang II binding was tested in cell membrane homogenates. [125I]Ang II was used as ligand, and Losartan and CGP 42112 were used as selective Ang II type 1 and type 2 antagonists, respectively. In APA, Ang II receptor density was 178.5 +/- 82.7 fmol/mg: however, due to the high degree of variability, the receptor density was not significantly higher than that in nontumorous adrenal cortex (59.3 +/- 8.4 fmol/mg). In Cush, the receptor density (27.6 +/- 8.2 fmol/mg; P < 0.05) was significantly lower than that in controls, whereas in Pheo and cortical carcinoma, Ang II binding was very low and in several cases almost undetectable. There was no remarkable difference in the Ang II receptor affinity among all tissues tested. The ratio between type 1 and type 2 Ang II receptors showed a large prevalence of type 1 in controls, APA, and three cases of Cush; in two cases of Cush, this ratio was reversed. In conclusion, our data indicate that Ang II receptors are normally expressed in APA and can also be detected in Cush, whereas they have a very low density in Pheo and adrenal carcinoma. Therefore, Ang II receptors are not involved in the lack of response to Ang II that is characteristic of APA; additionally, a reduction of Ang II receptors can be associated with dedifferentiation or malignancy of adrenal tumors. Further investigation of the expression and functional characterization of Ang II receptors is required to better clarify their possible role in adrenal tumorigenesis.

Opioid modulation of normal and pathological human chromaffin tissue.

To evaluate whether opioid receptor blockade might modulate sympathetic-adrenal activity, we studied the effects of placebo or naloxone administration on plasma catecholamine (CA) levels in a group of 13 normal subjects and 15 hypertensive patients suspected to have a pheochromocytoma. Diagnostic evaluation confirmed the presence of pheochromocytoma in 9 patients. Among these, 4 had a unilateral epinephrine (E)-secreting tumor, 3 had bilateral E-secreting tumors due to multiple endocrine adenomatosis type IIa, and 2 had a unilateral norepinephrine (NE)-secreting tumor. In each subject studied, CA secretion was evaluated by calculating the area (0-30 min) under the plasma hormone curves after placebo or naloxone administration. In normal subjects naloxone caused a significant increase (P less than 0.005) of E secretion, whereas NE did not change. Similarly, in the group of hypertensive patients, E secretion increased after naloxone (P less than 0.01). In pheochromocytoma patients naloxone caused a significant increase in E (P less than 0.05) and NE (P less than 0.01) secretion from E-producing tumors but no increase in the patients with NE-secreting pheochromocytomas. The study suggests that CA secretion from normal and pathological chromaffin tissue is modulated by endogenous opioids; this modulation seems particularly evident in patients with E-secreting pheochromocytoma.

Insulin resistance in Cushing's syndrome.

It is well established that cortisol excess causes insulin resistance in man, but the mechanisms responsible for this insulin resistance are poorly understood. We studied five women with Cushing's syndrome with impaired oral glucose tolerance tests and seven normal subjects, plotting the shape of the insulin-induced disposal dose-response curve obtained by means of the euglycemic clamp procedure during four different plasma insulin plateaus at four infusion rates of 21, 73, 760, and 1200 mU/M2 . min. Glucose disposal (M = mg/M2 . min) was calculated as glucose amount infused to maintain euglycemia. In Cushing's syndrome the dose-response curve was shifted to the right in comparison with normal subjects, with a significantly lower M (337 +/- 35 vs. 657 +/- 76 P less than 0.01) during the highest insulin infusion rate [maximal glucose disposal (MGD)] without any significant difference in the levels of insulin half-maximally effective in the stimulation of glucose utilization. Neither erythrocyte nor monocyte maximum insulin receptor binding were different between the two populations. Four Cushing's syndrome patients were studied again after surgical treatment. A marked improvement of MGD was observed without any significant change in insulin-binding capacity. These results, particularly the marked decrease in MGD, a typical feature of postreceptor defects, indicate that cortisol-induced insulin resistance in man is due to an impairment of peripheral insulin action located beyond the hormone-receptor binding step.

A survey on adrenal incidentaloma in Italy. Study Group on Adrenal Tumors of the Italian Society of Endocrinology.

The aim of this study was to perform a national survey on occasionally discovered adrenal masses [adrenal incidentalomas (AI)] under the auspices of the Italian Society of Endocrinology. This multicentric and retrospective evaluation of patients with AI includes 1096 cases collected in 26 centers between 1980 and 1995. Relevant information was obtained by means of a specifically tailored questionnaire. Of the 1096 forms received, 1004 were retained for final analysis. Patients were 420 males and 584 females, aged between 15-86 yr (median, 58 yr). Mass size (computed tomography measurement) ranged from 0.5-25 cm (median, 3.0 cm). Hormonal work-up demonstrated that 85% of the masses were nonhypersecretory, 9.2% were defined as subclinical Cushing's syndrome, 4.2% were pheochromocytomas, and 1.6% were aldosteronomas. Adrenalectomy was performed in 380 patients with removal of 198 cortical adenomas (52%), 47 cortical carcinomas (12%), 42 pheochromocytomas (11%), and other less frequent tumor types. Patients with carcinoma were significantly younger than patients with adenoma (median, 46; range, 17-84; vs. 57, 16-83 yr; P = 0.05). Adenomas were significantly smaller than carcinomas (3.5, 1-15 vs. 7.5, 2.6-25 cm; P < 0.001), and a cut-off at 4.0 cm had the highest sensitivity (93%) in differentiating between benign and malignant tumors. Hormonal work-up of patients with subclinical Cushing's syndrome showed low baseline ACTH in 79%, cortisol unsuppressibility after 1 mg dexamethasone in 73%, above normal urinary free cortisol in 75%, disturbed cortisol rhythm in 43%, and blunted ACTH response to CRH in 55%. Only 43% of patients with pheochromocytoma were hypertensive, and 86% showed elevated urinary catecholamines. All patients with aldosteronoma were hypertensive and had suppressed upright PRA. These results indicate that mass size is the most reliable variable in separating benign from malignant AI. Adrenalectomy should be recommended for AI greater than 4.0 cm because of the increased risk of malignancy, especially in young patients. Endocrine evaluation should be performed in all patients to identify silent states of hormone excess.

Mineralocorticoid hypertension due to a nasal spray containing 9 alpha-fluoroprednisolone.

The finding of hypokalemia and of low plasma renin activity (PRA) in a hypertensive patient suggests a diagnosis of primary hypermineralocorticoidism. Medications containing compounds with mineralocorticoid-like activity (licorice, carbenexolone) may also cause the same syndrome. Recently, we carried out detailed studies on 10 patients with severe hypertension and hypokalemic alkalosis, suppressed PRA and low aldosterone levels. Plasma levels of cortisol and ACTH were suppressed in most of the cases. Measurement of deoxycorticosterone and corticosterone (and in some patient of 18-hydroxydeoxycorticosterone and 18-hydroxycorticosterone) was not significantly higher than normal. Therapeutic trials of dexamethasone and aminoglutethimide were ineffective. In contrast, spironolactone and amiloride treatment resulted in substantial but incomplete amelioration of both hypertension and hypokalemia. All of the patients share a common history of chronic rhinitis and habitual use of large doses of nasal spray containing 9 alpha-fluoroprednisolone and vasoconstrictor agents. Withdrawal resulted in a complete remission of hypokalemia in one to two weeks in all patients. The hypertension and depressed levels of PRA, aldosterone and cortisol took longer to return to normal, varying from case to case; in all but one patient, the values returned to normal within two months. This report reveals another cause of factitious mineralocorticoid excess which may be considered in the differential diagnosis of hypokalemic hypertensive syndromes.

Immunoradiometric versus enzymatic renin assay: results of the Italian Multicenter Comparative Study. Italian Multicenter Study for Standardization of Renin Measurement.

OBJECTIVES: The measurement of plasma renin activity (PRA) is very convenient for estimating the action of the renin system, but its interlaboratory reproducibility is notoriously poor. This multicentre study aimed to examine whether an immunoradiometric assay which quantifies renin directly with monoclonal antibodies can reduce this limitation of the enzymatic assay. The study also aimed to establish the reference values of immunoreactive renin (IrR) in a large sample of normotensive subjects and patients with various pathophysiological conditions. DESIGN AND METHODS: PRA and IrR were measured once in each of the eight participant centres in eight pool plasma samples with a wide range of renin content; in seven centres these measurements were repeated twice more in order to compare the intralaboratory interassay reproducibility of both methods. Finally, PRA and IrR were measured in the supine and standing positions in 503 subjects including normal controls, patients with various forms of hypertension, patients with Cushing's and Bartter's syndromes, patients with hepatic cirrhosis and pregnant women. RESULTS: We found that both the inter- and intralaboratory coefficients of variation for PRA measurements were higher than those for IrR. In plasma samples from normal subjects and from patients, mean +/- SEM supine PRA and IrR ranged, respectively, from 0.08 +/- 0.03 ng/ml per h and 2.6 +/- 0.5 pg/ml in patients with Conn's syndrome to 7.2 +/- 2.5 ng/ml per h and 138 +/- 51 pg/ml in patients with hepatic cirrhosis. PRA and IrR were found to be significantly correlated in all laboratories (mean +/- SEM of correlation coefficients 0.84 +/- 0.03) and for all of the conditions (correlation coefficient ranging from 0.98 in patients with Cushing's syndrome to 0.50 in pregnant women). However, for the pregnant women the slope of the regression line depicting the PRA-IrR relationship was significantly steeper than for all of the other conditions. CONCLUSIONS: In our experience the inter- and intralaboratory reproducibilities of the immunoradiometric assay appear to be greater than can be achieved with the enzymatic assay, the difference being probably due to the greater complexity of the latter. The two methods provide superimposable information on the renin-angiotensin system activity, except in pregnancy, during which the PRA:IrR ratio is much higher than in the other conditions. Therefore, in this and other pathophysiological situations associated with marked angiotensinogen concentration alterations, the enzymatic assay may be still preferable for assessing the activity of the system accurately.