The contribution of testing in the fight against COVID-19: evidence from Italy.

BACKGROUND: In response to the epidemic of coronavirus disease 2019 (COVID-19), a few countries have rolled out widespread testing of the population, while in other countries only people requiring hospital admission are being screened. After an extensive testing strategy during the initial few weeks in the early phase of the epidemic, the Italian Ministry of Health made its testing policy more stringent. In this study we assess the contribution of the testing policy containing the spread of the COVID-19 epidemic in Northern Italy. METHODS: The analysis is focused on the evolution of the epidemic and related health intervention in four regions where ∼80% of the national death toll due to COVID-19 has occurred. The assumed under-estimation of asymptomatic cases has led us to make use of the number of deaths due to the epidemic to analyze the effectiveness of testing. The analysis is conducted through an autoregressive time-series approach where we use official data from the Ministry of Health. RESULTS: The results of the analysis confirm a negative relationship between the number of tests carried out and the progression of the epidemic. In particular, results reveal that the tests are particularly effective in breaking the chain of transmission when they are implemented at the early stages of the spread of the virus. CONCLUSIONS: A large-scale testing policy is recommended as a critical contribution to effectively contain the epidemic. In addition, it is highly recommended to set up all necessary measures to enable the quick scale-up of testing capacity whenever required.

Systemic inflammation and metabolic syndrome in stable COPD patients.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) has extrapulmonary effects that seems to be related with systemic inflammation. The relationship between metabolic syndrome which is an important determinant of systemic inflammation in general population and COPD is still not clear. The aim of the current study was to investigate the frequency of metabolic syndrome and C-reactive protein (CRP) levels, as a marker of systemic inflammation in stable COPD patients with different severity levels and in age and sex matched control group. PATIENTS AND METHODS: Ninety-one stable COPD patients and 42 control subjects were included in the study. The severity level in patients with COPD were determined according to GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria. ATP III (The National Cholesterol Education Program's Adult Treatment Panel III) was used in diagnosis of metabolic syndrome. Hs-CRP levels were measured in venous samples of patients and control subjects. RESULTS: The frequency of metabolic syndrome was found higher in patient group than control subjects, especially in GOLD stages I, II (p= 0.004). Abdominal obesity, hypertension, hyperglycemia components of metabolic syndrome were significantly more prevalent in patient group (p< 0.0001). Increased CRP levels were higher in control and patient groups in all GOLD stages, with metabolic syndrome than without metabolic syndrome (p= 0.047, p= 0.217, p< 0.001, p= 0.05, p= 0.467). CONCLUSION: The study showed that frequency of metabolic syndrome was higher in stable COPD patients than control subjects and general Turkish population. Abdominal obesity, hypertension and hyperglycemia were significantly more prevalent in patient group. Systemic inflammation was more intense in COPD patients with metabolic syndrome than without metabolic syndrome.

Cardiac autonomic function and global left ventricular performance in autoimmune eauthyroid chronic thyroiditis: is treatment necessary at the euthyroid stage?

OBJECTIVE: Autoimmune chronic thyroiditis (ACT) is characterized by lymphocyte infiltration in the thyroid gland and the presence of antithyroid antibodies in serum. Medical treatment does not affect antibody levels and treatment decision is not definite yet for the euthyroid patients. We aimed to evaluate cardiac autonomic function and global left ventricular performance in autoimmune euthyroid chronic thyroiditis and determine the need for medical treatment. METHOD: We studied 30 ACT patients and 25 healthy control subjects. Cardiac autonomic function is evaluated by heart rate recovery (HRR). Global left ventricular performance is evaluated by two-dimensional echocardiography and pulsed-wave tissue Doppler echocardiography. RESULTS: There was no difference between patients and controls with respect to clinical and biochemical parameters except hemoglobin (13.67 ± 1.25 g/dL, 14.51 ± 1.35 g/dL, p:0.047) and low density lipoprotein (120.71 ± 24.91 mg/dL, 100.55 ± 14.73 mg/dL, p: 0.003). Tei index was significantly higher in ACT group (0.521 ± 0.074, 0.434 ± 0.034, P < 0.0001). E'/A' was found to be significantly lower (1.234 ± 0.42, 1.750 ± 0.291, P < 0.0001) and E/E' was found to be higher than the controls (8.482 ± 0.449, 6.039 ± 0.209, P < 0.0001). HRR was significantly lower than the controls (20 ± 4 BPM, 30 ± 8 BPM, P < 0.0001). CONCLUSION: Although left ventricular performance is found to be normal by conventional echocardiographic methods, it is found to be impaired when Tei index and tissue Doppler parameters are used. Cardiac autonomic function is also impaired in ACT patients. As a result of these cardiac changes, medical treatment may be considered earlier, even at the euthyroid stage.

Molecular economy of nature with two thyrotropins from different parts of the pituitary: pars tuberalis thyroid-stimulating hormone and pars distalis thyroid-stimulating hormone.

Thyrotropin (TSH) is classically known to be regulated by negative feedback from thyroid hormones and stimulated by thyrotropin-releasing hormone (TRH) from the hypothalamus. At the end of the 1990s, studies showed that thyrotroph cells from the pars tuberalis (PT) did not have TRH receptors and their TSH regulation was independent from TRH stimulation. Instead, PT-thyrotroph cells were shown to have melatonin-1 (MT-1) receptors and melatonin secretion from the pineal gland stimulates TSH-ß subunit formation in PT. Electron microscopy examinations also revealed some important differences between PT and pars distalis (PD) thyrotrophs. PT-TSH also have low bioactivity in the peripheral circulation. Studies showed that they have different glycosylations and PT-TSH forms macro-TSH complexes in the periphery and has a longer half-life. Photoperiodism affects LH levels in animals via decreased melatonin causing increased TSH-ß subunit expression and induction of deiodinase-2 (DIO-2) in the brain. Mammals need a light stimulus carried into the suprachiasmatic nucleus (which is a circadian clock) and then transferred to the pineal gland to synthesize melatonin, but birds have deep brain receptors and they are stimulated directly by light stimuli to have increased PT-TSH, without the need for melatonin. Photoperiodic regulations via TSH and DIO 2/3 also have a role in appetite, seasonal immune regulation, food intake and nest-making behaviour in animals. Since humans have no clear seasonal breeding period, such studies as recent ''domestication locus'' studies in poultry are interesting. PT-TSH that works like a neurotransmitter in the brain may become an important target for future studies about humans.

Postpartum thyroiditis and hypothalamo-hypophysial insufficiency in the same woman with successive pregnancies: a case report.

OBJECTIVE: Although the incidence of postpartum autoimmune disorders of endocrine glands are not rare, the presence of two different entities in the same patient with two different pregnancies is uncommon. METHODS: We present a 35-year-old woman whose story starts with her first pregnancy when she was 29 years old, she had the diagnosis of postpartum thyroiditis with hypothyroidism.We followed up the patient when she had her second pregnancy. RESULTS: When she was being followed up with levothyroxine replacement, 5 years later she had her second delivery after which she had complaints of polydipsia, polyuria, weight loss and had the diagnosis of central diabetes insipitus and she has started desmopressin treatment and 17 months later the delivery she again applied with amenorrhea, continuation of lactation later she noticed oligomenorrhea, and her gonadotropin levels were found to be low as well as her TSH levels, although the L-thyroxine treatment dose was not changed. Dynamic tests of hypophysis revealed hypophyseal insufficiency and repeated hypophyseal MRI was in concordance with lymphocytic hypophysitis which explains the pattern of endocrinological abnormalities after the second delivery. CONCLUSION: This case signals role of autoimmune mechanisms underlying the endocrinopathies seen after successive pregnancies of the same patient.

Relationship between serum zinc levels, thyroid hormones and thyroid volume following successful iodine supplementation.

OBJECTIVE: Zinc is essential for many biochemical processes and also for cell proliferation. Thyroid hormones influence zinc metabolism by affecting zinc absorption and excretion. Additionally, zinc deficiency affects thyroid function. The aim of the present study was to evaluate a possible association of zinc levels with thyroid volume, thyroid hormones and thyroid autoantibody levels in healthy subjects, patients with autoimmune thyroid disease (AITD) and patients with nodular goitre following successful iodine supplementation. This is a cross-sectional study in which 201 subjects who were not under medical treatment and did not have previous thyroid surgery or radio-iodine treatment were evaluated. Seventy patients had nodular goitre, 67 AITD and 64 had normal thyroid. Thyroid volume was calculated by ultrasonographic measurements. Serum free T4, T3, TSH, anti-thyroglobulin and anti-thyroid peroxidase levels were determined by appropriate methodology. RESULTS: In patients with normal thyroid, zinc levels were significantly positively correlated with free T3 levels (p<0.001). In the nodular goitre group, thyroid volume was negatively correlated with TSH and circulating zinc levels (p=0.014 and p=0.045, respectively). In the AITD group, thyroid autoantibodies and zinc were significantly positively correlated. Multiple regression analysis revealed a significant relationship between thyroid volume and zinc only in the patients with nodular goitre (p=0.043). CONCLUSION: There was significant correlation of serum zinc levels with thyroid volume in nodular goitre patients, with thyroid autoantibodies in AITD and with free T3 in patients with normal thyroid.

Omega-3 polyunsaturated fatty acids: their potential role in blood pressure prevention and management.

Omega-3 (omega-3) polyunsaturated fatty acids (PUFAs) from fish and fish oils appear to protect against coronary heart disease: their dietary intake is in fact inversely associated with cardiovascular disease morbidity/mortality in population studies. Recent evidence suggests that at least a part of this protective effect is mediated by a relatively small but significant decrease in blood pressure (BP) level. In fact, omega-3 PUFAs exhibit wide-ranging biological actions that include regulating both vasomotor tone and renal sodium excretion, partly competing with omega-6 PUFAs for common metabolic enzymes and thereby decreasing the production of vasoconstrictor rather than vasodilator and anti-inflammatory eicosanoids. PUFAs also reduce angiotensin-converting enzyme (ACE) activity, angiotensin II formation, Tumor Growth Factor-beta (TGF-beta) expression, enhance endothelial nitric oxide (NO) generation and activate the parasympathetic nervous system. The final results are improved vasodilation and arterial compliance of both small and large arteries. Preliminary clinical trials involving normotensive and hypertensive dyslipidaemic patients, diabetics and elderly subjects, confirm this working hypothesis: 3 meta-analyses suggest that PUFAs are able to slightly, but significantly improve arterial hypertension. Future research will clarify if PUFA supplementation could improve the antihypertensive action of specific BP lowering drug classes and of statins.

High-density Lipoprotein (HDL) Dysfunction and the Future of HDL.

Although High Density Lipoprotein Cholesterol (HDL-C) levels are inversely proportional to cardiovascular risk in many studies, recent pharmacological interventional studies with HDL-C raising strategies did not show a benefit in terms of vascular events. The HDL particle is heterogenous with anti-atherogenic functions and non-vascular effects. Many factors affect HDL components and may either cause compositional changes, post-translational modifications of proteins, or alter lipids and other cargo molecules; generally these factors cause more than one of these changes, resulting in functional differences. Therefore, the role of lipoproteins change in different physical and disease conditions. Mainly, in proteome, Apolipoprotein A1 (Apo-A1), Myeloperoxidase (MPO), Paroxonase (PON) are affected by inflammation or glycation-related factors; and especially esterification or unesterification of lipids, changes in phospholipid or unsaturated lipid content change the HDL function. Measuring the HDL-C level is probably not a good predictor of its cardiovascular benefits, and methods to evaluate HDL functions are required. In current medical practice, it is not simple and feasible to measure different functions of this lipoprotein, but near-future strategies may be developed. Meanwhile, as we learn more about HDL structure and the role of each component, we can develop therapeutic approaches to improve HDL function. Apo-A1-mimetics, reconstituted HDL, nanoparticles and microRNA therapies could be promising as anti-atherosclerotic therapies. They may even provide useful therapies for the treatment of some non-cardiovascular diseases.

Comparison of Early Total Thyroidectomy with Antithyroid Treatment in Patients with Moderate-Severe Graves' Orbitopathy: A Randomized Prospective Trial.

BACKGROUND: The optimal therapeutic choice for Graves' hyperthyroidism in the presence of moderate-severe Graves' orbitopathy (GO) remains controversial. OBJECTIVES: We aimed to compare GO course in patients with moderate-severe GO treated with early total thyroidectomy (TTx) versus antithyroid drug (ATD) regimens, in a prospective, randomized manner. METHODS: Forty-two patients with moderate-severe GO were enrolled. A total of 4.5 g of pulse corticosteroids were given intravenously to all patients before randomization. Patients in the first group were given TTx, whereas patients in the second group were treated with ATDs. TSH was kept between 0.4 and 1 mIU/l. The clinical course of GO was evaluated with proptosis, lid aperture, clinical activity score (CAS), and diplopia. RESULTS: Eighteen and 24 patients were randomized to the TTx and ATD groups, respectively. Thyroid autoantibodies decreased significantly, and there were significant improvements in proptosis, lid aperture, and CAS in the TTx group. While in the ATD group the decrement in thyroid autoantibodies was not significant, there were significant improvements in proptosis and CAS. When the TTx group was compared with the ATD group, anti-TPO, anti-Tg, and TSH-receptor antibodies were significantly decreased in the TTx group (p < 0.01), but there was no significant difference with respect to proptosis, lid aperture, CAS, and diplopia between the two groups during a median (min.-max.) follow-up period of 60 months (36-72). CONCLUSION: Although no definitive conclusions could be drawn from the study, mainly due to limited power, early TTx and the ATD treatment regimens, followed by intravenous pulse corticosteroid therapy, seemed to be equally effective on the course of GO in this relatively small group of patients with moderate-severe GO during a median (min.-max.) follow-up period of 60 months (36-72).

Is there U-turn from insulin back to pills in diabetes?

Type 2 diabetes is characterized by insulin resistance together with progressive loss of beta-cell function. After recognition of gluco- and lipo-toxicity, attention was focused on the preservation and/or restoration of beta cell function, especially at the early stages of the diabetes, with better beta-cell reserve and in the absence of complications. Early treatment of glucotoxicity with insulin was searched by early insulin treatment studies, and these studies have some promising results, pointing the possibility of "remission" of diabetes in some patients. According to the results of these studies, patients with early diagnosis of diabetes, the ones with better beta cell reserve, patients with low tendency for "insulin-abuse" could make "U"-turn from insulin to pills or even drug-free life. Criteria to turn back to pills could be listed as disappearance of diabetic symptoms, daily insulin need < 0.25 unit/kg, euglycemia in both fasting and postprandial state, and better beta cell function. The main problems in early insulin treatment are the ''insulin resistance'' of both patients and doctors, hypoglycemia, weight gain and increased appetite. Meanwhile, hyperinsulinemia desensitizes receptors and causes worsening of situation in a vicious cycle of insulin resistance and hyperglycemia. Therefore, patients should be selected properly and U-turn could be performed in relevant conditions explained in the text. It could be possible to see early insulin treatment and U-turn strategies in future guidelines for type 2 diabetes.

Insulin resistance in brain and possible therapeutic approaches.

Although the brain has long been considered an insulin-independent organ, recent research has shown that insulin has significant effects on the brain, where it plays a role in maintaining glucose and energy homeostasis. To avoid peripheral insulin resistance, the brain may act via hypoinsulinemic responses, maintaining glucose metabolism and insulin sensitivity within its own confines; however, brain insulin resistance may develop due to environmental factors. Insulin has two important functions in the brain: controlling food intake and regulating cognitive functions, particularly memory. Notably, defects in insulin signaling in the brain may contribute to neurodegenerative disorders. Insulin resistance may damage the cognitive system and lead to dementia states. Furthermore, inflammatory processes in the hypothalamus, where insulin receptors are expressed at high density, impair local signaling systems and cause glucose and energy metabolism disorders. Excessive caloric intake and high-fat diets initiate insulin and leptin resistance by inducing mitochondrial dysfunction and endoplasmic reticulum stress in the hypothalamus. This may lead to obesity and diabetes mellitus (DM). Exercise can enhance brain and hypothalamic insulin sensitivity, but it is the option least preferred and/or continuously practiced by the general population. Pharmacological treatments that increase brain and hypothalamic insulin sensitivity may provide new insights into the prevention of dementia disorders, obesity, and type 2 DM in the future.

Nutraceuticals for metabolic syndrome management: from laboratory to benchside.

Metabolic syndrome (MetS) is a world-wide epidemic disease associated with increased morbidity and mortality. Treatment strategies include pharmacologic and non-pharmacologic methods, with varying degrees of success rate all over the world. Pharmaceutical interest in this field is growing, together with patients' requests for supplementary (or "alternative") treatments. The knowledge of nutraceuticals beneficial effects in subjects with the MetS could help us to better define the appropriate treatment for these subjects, in particular those with contraindications for commonly used drugs, or to achieve guidelines suggested targets. On the other side, it could be not convenient to use a nutraceutical to treat each metabolic syndrome component (i.e. from 3 to 5) in each affected subjects. Thus, this review tries to focus on widely marketed nutraceuticals with clinically demonstrated effects on more than one component of the MetS, namely omega-3 fatty acids, berberine, psyllium and other soluble fibers, cinnamon, chromium picolinate, banaba, and bitter gourd.

Efficacy and safety profile of evolocumab (AMG145), an injectable inhibitor of the proprotein convertase subtilisin/kexin type 9: the available clinical evidence.

INTRODUCTION: Despite the proven efficacy of statins, they are often reported to be inadequate to achieve low-density lipoprotein cholesterol (LDL-C) goals (especially in high-risk patients). Moreover, a large number of subjects cannot tolerate statins or full doses of these drugs. Thus, there is a need for additional effective LDL-C reducing agents. AREAS COVERED: Evolocumab (AMG145) is a monoclonal antibody inhibiting the proprotein convertase subtilisin/kexin type 9 that binds to the liver LDL receptor and prevents it from normal recycling by targeting it for degradation. Phase I and II trials revealed that its subcutaneous injection, either alone or in combination with statins, is able to reduce LDL-C from 40 to 80%, apolipoprotein B100 from 30 to 59% and lipoprotein(a) from 18 to 36% in a dose-dependent manner. The incidence of side effects seems to be low and mainly limited to nasopharyngitis, injection site pain, arthralgia and back pain. EXPERT OPINION: Evolocumab is an innovative powerful lipid-lowering drug, additive to statins and with an apparently large therapeutic range associated to a low rate of mild adverse events. If available data will be confirmed in long-term trials with strong outcomes, Evolocumab will provide an essential tool to treat high-risk patients who need to reach ambitious LDL-C target.

Safety and tolerability of injectable lipid-lowering drugs: a review of available clinical data.

INTRODUCTION: To answer the need of a better low-density lipoprotein (LDL) cholesterol control in statin-treated patients at high risk for cardiovascular disease, new injectable lipid-lowering drugs with innovative mechanisms of action are in advanced phase of development or have just been approved. AREAS COVERED: Evolocumab and alirocumab are fully human monoclonal antibodies inhibiting the proprotein convertase subtilisin/kexin type 9 (PCSK9) that binds to hepatic LDL receptor and prevents it from normal recycling by targeting it for degradation. Mipomersen specifically binds to a segment of the human apolipoprotein B100 messenger RNA, blocking the translation of the gene product. Phase II (for evolocumab and alirocumab) and III (for evolocumab) trials show that PCSK9 inhibitors are equally well tolerated, with adverse events mainly limited to mild-to-moderate nasopharyngitis, injection-site pain, arthralgia and back pain. Mipomersen use is mainly associated to hepatosteatosis, increased transaminases (> 3 times the upper limit of normal), mild-to-moderate injection-site reactions and flu-like symptoms. EXPERT OPINION: PCSK9 inhibitors have demonstrated their good safety and tolerability in a large number of subjects with different clinical conditions, including statin-intolerance, enlarging their potential use in a broader range of patients. Further data on long-term mipomersen safety are required.

Late-onset congenital adrenal hyperplasia with Cushing syndrome.

Although hirsutism is classically part of the clinical presentation of polycystic ovarian syndrome (PCOS), congenital adrenal hyperplasia and Cushing's syndrome (CS), CS associated with underlying late-onset congenital adrenal hyperplasia (LCAH) in an adult has not been previously reported. We herein present the case of a 25-year-old woman who was followed for PCOS for seven years. After undergoing detailed tests described within the text, she received the diagnosis of LCAH and was found to have point mutations. Interestingly, she later had diagnosis of endogenous CS that regressed folowing excision of an adrenal adenoma found on MRI. The present patient thus exhibited the coexistence of two paradoxical endocrine pathologies.

Hyperthyroidism and cardiovascular complications: a narrative review on the basis of pathophysiology.

Cardiovascular complications are important in hyperthyroidism because of their high frequency in clinical presentation and increased mortality and morbidity risk. The cause of hyperthyroidism, factors related to the patient, and the genetic basis for complications are associated with risk and the basic underlying mechanisms are important for treatment and management of the disease. Besides cellular effects, hyperthyroidism also causes hemodynamic changes, such as increased preload and contractility and decreased systemic vascular resistance causes increased cardiac output. Besides tachyarrythmias, impaired systolic ventricular dysfunction and diastolic dysfunction may cause thyrotoxic cardiomyopathy in a small percentage of the patients, as another high mortality complication. Although the medical literature has some conflicting data about benefits of treatment of subclinical hyperthyroidism, even high-normal thyroid function may cause cardiovascular problems and it should be treated. This review summarizes the cardiovascular consequences of hyperthyroidism with underlying mechanisms.

Role of cytological characteristics of benign thyroid nodules on effectiveness of their treatment with levothyroxine.

INTRODUCTION: Levothyroxine (LT4) therapy has been used for the treatment of euthyroid nodular goiter, but there are controversial results about its usefulness. We aimed to evaluate the possible role of benign nodules' cytological characteristics in response to LT4 therapy. MATERIAL AND METHODS: In total, 93 patients with 128 nodules were included in the study; 74 of the nodules were treated with LT4 (group 1), and 54 of them had no medication (group 2). The subgroups consisted of adenomatous nodules, colloid nodules and cystic nodules. RESULTS: In group 1, mean thyroid volume and mean nodule volume were reduced significantly (p = 0.002 and p = 0.022, respectively) with low-normal level thyrotropin (TSH) suppression (between 0.3 mIU/ml and 1.0 mIU/ml), while there were no significant changes in group 2. When we evaluated changes of the initial and last nodule volumes in cytological subgroups, only colloid nodules in group 1 had significant reduction (p = 0.040) and the others had no significant changes. By omitting the colloid nodules, when the other nodules were revaluated, there were no significant changes in either group. CONCLUSIONS: On the basis of these results, obtained from a large sample of Anatolian patients, it is possible that LT4 therapy leads to significant reductions of both thyroid volume and nodule size in colloid nodules, but not in other kinds of benign nodules.

Impact of physical activity on inflammation: effects on cardiovascular disease risk and other inflammatory conditions.

Since the 19(th) century, many studies have enlightened the role of inflammation in atherosclerosis, changing our perception of "vessel plaque due to oxidized lipoproteins", similar to a "rusted pipe", towards a disease with involvement of many cell types and cytokines with more complex mechanisms. Although "physical activity" and "physical exercise" are two terms with some differences in meaning, compared to sedentary lifestyle, active people have lower cardiovascular risk and lower inflammatory markers. Activities of skeletal muscle reveal "myokines" which have roles in both the immune system and adipose tissue metabolism. In vitro and ex-vivo studies have shown beneficial effects of exercise on inflammation markers. Meanwhile in clinical studies, some conflicting results suggested that type of activity, exercise duration, body composition, gender, race and age may modulate anti-inflammatory effects of physical exercise. Medical data on patients with inflammatory diseases have shown beneficial effects of exercise on disease activity scores, patient well-being and inflammatory markers. Although the most beneficial type of activity and the most relevant patient group for anti-inflammatory benefits are still not clear, studies in elderly and adult people generally support anti-inflammatory effects of physical activity and moderate exercise could be advised to patients with cardiovascular risk such as patients with metabolic syndrome.

Metformin and its clinical use: new insights for an old drug in clinical practice.

Metformin is generally recommended as first-line treatment in type 2 diabetes, especially in overweight patients, but in recent years new indications for its use have emerged. Metformin has been found to be safe and efficacious both as monotherapy and in combination with all oral antidiabetic agents and insulins. If metformin use during pregnancy and the lactation period is supported by few data, it could be indicated for women with polycystic ovary syndrome, since it could diminish circulating androgens and insulin resistance, thus ameliorating the ovulation rate. Metformin seems to reduce cancer risk, which appears to be increased in diabetics, and is a promising agent for oncoprevention and chemotherapy combinations. Moreover, metformin could find a place in the treatment of non-alcoholic fatty liver disease. Lactic acidosis could be decreased by avoiding metformin use in patients with hypovolemia, sepsis, renal impairment, hypoxic respiratory diseases and heart failure, in the preoperative period and before intravenous injection of contrast media.