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Biomedical subjects

E Ferrannini

Publications and source records attributed to E Ferrannini.

At least 19 recordsLinked to original sources

Effect of short-term folic acid supplementation on insulin sensitivity and inflammatory markers in overweight subjects.

OBJECTIVE: Inflammation plays a pivotal role in the atherosclerotic process, and some chemokines seem to be crucial in the pathogenesis of vascular damage. High-serum homocysteine, recently recognized as an independent risk factor for vascular disease might increase cytokine and chemokine levels, thus amplifying endothelial damage; moreover, it might worse insulin resistance, thus further contributing to enhance cardiovascular risk. The effect of folic acid supplementation in improving in vivo endothelial function is still debated. In this study, we investigated the effect of folic acid supplementation on insulin sensitivity and peripheral markers of inflammation in overweight healthy subjects. DESIGN: The study was performed as an unmasked randomized placebo-controlled trial of 12 weeks duration. SUBJECTS: Sixty healthy volunteers with normal glucose tolerance and BMI between 25 and 29 kg/m2 were enrolled. MEASUREMENTS: Biochemical parameters and plasma concentrations of homocysteine and of some inflammatory molecules were measured at baseline and at the end of the study, together with an estimation of insulin sensitivity. RESULTS: Subjects receiving folic acid supplementation showed a decrement of homocysteine and an amelioration of insulin sensitivity; this treatment was also associated with a significant drop in the circulating concentration of monocyte chemoattractant protein-1, interleukin-8 and C-reactive protein, in the absence of any significant variation of BMI or fat mass. CONCLUSIONS: In healthy overweight subjects a short-term folic acid supplementation reduces the circulating level of some inflammatory mediators independently of weight change, thus suggesting a potential therapeutic role for folic acid in the protection from atherogenesis and cardiovascular diseases.

Adult↗

Effects of metformin and thiazolidinediones on suppression of hepatic glucose production and stimulation of glucose uptake in type 2 diabetes: a systematic review.

AIMS/HYPOTHESIS: Insulin resistance, which manifests itself as endogenous glucose overproduction and reduced insulin-mediated glucose uptake, is a core defect in type 2 diabetes. Metformin and the peroxisome proliferator-activated receptor-gamma agonists, the thiazolidinediones (TZDs), both lower glucose, although their mechanism of action is still subject to debate. This review analyses the evidence relevant to these mechanisms in vivo. MATERIALS AND METHODS: A systematic search of MEDLINE identified a total of 42 clinical studies that investigated the effects of TZDs (n=23) and/or metformin (n=19) on endogenous glucose production (using tracer glucose techniques) and peripheral glucose disposal (using the euglycaemic-hyperinsulinaemic clamp) in patients with type 2 diabetes (n=549). The original variables assessed were converted into standardised units and their mean group values were listed separately for open and placebo-controlled studies. Statistical analysis was scarried out, treating mean group values as individual values and comparing results (both as absolute values and percentage changes from baseline) across study categories (open vs placebo-controlled, TZDs vs metformin). RESULTS: Both TZDs and metformin enhance insulin suppression of endogenous glucose production and fasting plasma glucose clearance. TZDs, but not metformin, also improve insulin-mediated glucose uptake at all insulin levels. CONCLUSIONS/INTERPRETATION: In patients with type 2 diabetes, metformin improves fasting hepatic insulin sensitivity and glucose clearance; TZDs improve fasting hepatic insulin sensitivity and glucose clearance, and potentiate glucose disposal under insulinised conditions.

Animals↗

Acute vascular events and electrolytes variations in elderly patients.

Alterations in electrolyte balance have been claimed to play a role in the pathophysiology of coronary heart disease; however, the relationship between the electrolyte pattern and other clinical variables immediately after an acute vascular event is unclear. The aim of the present study was to test whether electrolyte and microelement changes characterize the acute phase in patients with different degrees of glucose tolerance admitted to the hospital shortly after an acute cardiovascular or cerebrovascular ischemic event. Two hundred consecutive patients with either myocardial infarction or stroke (SP group), stratified by degree of glucose tolerance, were studied within six hours of admission, and compared against 125 patients admitted for conditions other than acute vascular ischemia (CP). Routine laboratory parameters and serum Na, K, Cl, Mg and Ca concentrations were determined in all patients and compared to those recorded within six months before the admission. Relative to CP and independently of confounding factors including glucose tolerance status, the SP group showed significantly higher plasma glucose and insulin concentrations, higher creatinine and a modified serum electrolyte pattern characterized by significantly lower potassium and magnesium levels and by hypercalcemia and hyperphosphatemia. Irrespective of glucose tolerance, the first hours following an acute vascular event are characterized by marked insulin resistance with a consistent shift in the serum electrolyte pattern. This pattern is the physiological consequence of the attendant compensatory hyperinsulinemia. Its significance for the evolution of ischemic damage remains to be established.

Aged↗

Impaired beta cell glucose sensitivity and whole-body insulin sensitivity as predictors of hyperglycaemia in non-diabetic subjects.

AIMS/HYPOTHESIS: The aim of this prospective study was to investigate predictors of deteriorating glucose tolerance in subjects of British extraction. METHODS: A total of 156 non-diabetic subjects (86 with a family history of type 2 diabetes) underwent a 75-g OGTT and anthropometric assessment at baseline and 5 years later. Pancreatic beta cell function and whole-body insulin sensitivity were studied by model assessment. Subjects were classified as progressors if glucose tolerance moved one or more steps from normal, impaired fasting glucose, impaired glucose tolerance and diabetes over the follow-up period. RESULTS: At baseline, the progressors (n=22) had increased adiposity and a higher proportion of familial diabetes and abnormal glucose tolerance than non-progressors. Baseline pancreatic beta cell sensitivity to changes in glucose (p<0.02) and whole-body insulin sensitivity (p<0.0001) were decreased in the progressors. Logistic regression revealed that baseline and follow-up changes in beta cell glucose sensitivity and insulin sensitivity, rather than the classical clinical predictors (adiposity, familial diabetes and glucose levels), were the key independent predictors of progression (explaining over 50% of the progression). CONCLUSIONS/INTERPRETATION: Impaired pancreatic beta cell glucose sensing and whole-body insulin sensitivity predict progression to hyperglycaemia. Strikingly, these pathophysiological changes override the importance of the clinical risk factors and highlight potential metabolic targets for prevention strategies.

Adult↗

Visceral fat and beta cell function in non-diabetic humans.

AIMS/HYPOTHESIS: Preferential visceral adipose tissue (VAT) accumulation has been clearly associated with insulin resistance. In contrast, the impact of visceral obesity on beta cell function is controversial. METHODS: In 62 non-diabetic women and men (age 24-69 years, BMI 21-39 kg/m2), we measured VAT and subcutaneous adipose tissue (SAT) fat mass by magnetic resonance imaging. We also measured insulin secretion and beta cell function by C-peptide deconvolution and physiological modelling of data from a frequently sampled, 75-g, 3-h OGTT, respectively. RESULTS: VAT (range 0.1-3.1 kg) was strongly related to sex, age and BMI; SAT was related to sex and BMI. Controlling for sex, age, BMI and SAT by multivariate analysis, excess VAT was associated with a clinical phenotype comprising higher plasma glucose levels, BP, heart rate and serum transaminases. The corresponding metabolic phenotype consisted of insulin resistance (partial r=-0.38) and hyperinsulinaemia (partial r=0.29). The latter, however, was appropriate for the degree of insulin resistance regardless of obesity and abdominal fat distribution. Moreover, none of the model-derived parameters describing beta cell function (glucose sensitivity, rate sensitivity and potentiation) was independently associated with excess VAT. CONCLUSIONS/INTERPRETATION: In non-diabetic Caucasian adults of either sex, preferential visceral fat deposition in itself is part of an insulin-resistant phenotype. The insulin secretory response to a physiological challenge is increased to fully compensate for the insulin resistance, but the dynamics of beta cell function (glucose sensitivity, rate sensitivity and potentiation) are largely preserved.

Adipose Tissue↗

Long-term follow-up of 106 multiple sclerosis patients undergoing interferon-beta 1a or 1b therapy: predictive factors of thyroid disease development and duration.

BACKGROUND: Conflicting data have been reported on the association between interferon (IFN)-beta therapy of multiple sclerosis (MS) patients and thyroid disease development. AIMS: The goals of this study are as follows: to assess the actual occurrence of thyroid dysfunction and autoimmunity during long-term IFN-beta therapy; to establish the possible presence of predictive factors for thyroid dysfunction development and duration; and to suggest an effective follow-up protocol for patients receiving long-term IFN-beta therapy. STUDY PROTOCOL: A total of 106 MS patients (76 women) underwent IFN-beta 1a or 1b therapy for up to 84 months (median, 42 months). Thyroid function and autoimmunity were assessed at baseline and every 3-6 months throughout the treatment course. RESULTS: Baseline thyroid autoimmunity was detected in 8.5% of patients and hypothyroidism in 2.8%. Thyroid dysfunction (80% hypothyroidism, 92% subclinical, 56% transient) developed in 24% (68% with autoimmunity) of patients and autoimmunity in 22.7% (45.5% with dysfunction), without significant differences between the two cytokines; 68% of dysfunctions occurred within the first year. Autoimmunity emerged as the only predictive factor for dysfunction development (relative risk, 8.9), whereas sustained disease was significantly associated with male gender (P < 0.003). CONCLUSIONS: Both incident thyroid autoimmunity and dysfunction frequently occur in MS patients during IFN-beta therapy, particularly within the first year of treatment. Thyroid dysfunction is generally subclinical and transient in over than half of cases; preexisting or incident autoimmunity emerged as the only significant predictive factor for thyroid dysfunction development. Thyroid function and autoimmunity assessment is mandatory within the first year of IFN-beta therapy; thereafter, serum TSH measurement only in patients with thyroid disease could be sufficient.

Adult↗

Insulin resistance in non-diabetic patients with non-alcoholic fatty liver disease: sites and mechanisms.

AIMS/HYPOTHESIS: Non-alcoholic fatty liver disease (NAFLD) has been associated with the metabolic syndrome. However, it is not clear whether insulin resistance is an independent feature of NAFLD, and it remains to be determined which of the in vivo actions of insulin are impaired in this condition. METHODS: We performed a two-step (1.5 and 6 pmol min(-1) kg(-1)) euglycaemic insulin clamp coupled with tracer infusion ([6,6-2H2]glucose and [2H5]glycerol) and indirect calorimetry in 12 non-obese, normolipidaemic, normotensive, non-diabetic patients with biopsy-proven NAFLD and six control subjects. RESULTS: In NAFLD patients, endogenous glucose production (basal and during the clamp) was normal; however, peripheral glucose disposal was markedly decreased (by 30% and 45% at the low and high insulin doses, respectively, p<0.0001) at higher plasma insulin levels (p=0.05), due to impaired glucose oxidation (p=0.003) and glycogen synthesis (p<0.001). Compared with control subjects, glycerol appearance and lipid oxidation were significantly increased in NAFLD patients in the basal state, and were suppressed by insulin to a lesser extent (p<0.05-0.001). The lag phase of the in vitro copper-catalysed peroxidation of LDL particles was significantly shorter in the patients than in the control subjects (48+/-12 vs 63+/-13 min, p<0.04). Lipid oxidation was significantly related to endogenous glucose production, glucose disposal, the degree of hepatic steatosis, and LDL oxidisability. CONCLUSIONS/INTERPRETATION: Insulin resistance appears to be an intrinsic defect in NAFLD, with the metabolic pattern observed indicating that adipose tissue is an important site.

3-Hydroxybutyric Acid↗

The metabolic syndrome: time for a critical appraisal. Joint statement from the American Diabetes Association and the European Association for the Study of Diabetes.

BACKGROUND: The term 'metabolic syndrome' refers to a clustering of specific cardiovascular disease (CVD) risk factors whose underlying pathophysiology is thought to be related to insulin resistance. METHODS: Since the term is widely used in research and clinical practice, we undertook an extensive review of the literature in relation to the syndrome's definition, underlying pathogenesis, association with cardiovascular disease and to the goals and impact of treatment. DISCUSSION: While there is no question that certain CVD risk factors are prone to cluster, we found that the metabolic syndrome has been imprecisely defined, there is a lack of certainty regarding its pathogenesis, and there is considerable doubt regarding its value as a CVD risk marker. Our analysis indicates that too much critically important information is missing to warrant its designation as a 'syndrome'. CONCLUSION: Until much-needed research is completed, clinicians should evaluate and treat all CVD risk factors without regard to whether a patient meets the criteria for diagnosis of the 'metabolic syndrome'.

Body Mass Index↗

Anti-CD38 autoimmunity in children with newly diagnosed type 1 diabetes mellitus.

AIMS: To test for anti-CD38 autoimmunity in children with newly-diagnosed type 1 diabetes mellitus (DM1). METHODS: Serum anti-CD38 autoantibodies were detected by Western blot in 270 children (130 girls, 140 boys, mean age 8 +/- 4 years) with newly-diagnosed DM1 and 179 gender- and age-matched non-diabetic children. In 126 diabetic children, another blood sample was obtained 15 +/- 4 months after the diagnosis. RESULTS: Anti-CD38 autoantibody titers at least 3 SD above the mean value for the control group were found in 4.4% of children with DM1 vs 0.6% of controls (chi2 = 5.8, p <0.016). No statistical differences were observed between anti-CD38 positive and negative patients in terms of phenotype. At follow-up, of six diabetic children who were positive for anti-CD38 antibodies, two were new cases. A positive correlation was found between the antibody titer of diabetic sera at diagnosis and follow up (r = 0.46, p <0.0001). CONCLUSION: An autoimmune reaction against CD38, a protein expressed in human islets, is associated with newly-diagnosed DM1. In children with DM1, CD38 autoimmunity increases with time and persists.

ADP-ribosyl Cyclase 1↗

Type I interferons modulate the expression of thyroid peroxidase, sodium/iodide symporter, and thyroglobulin genes in primary human thyrocyte cultures.

We evaluated in primary human thyrocyte cultures the effect of interferon (IFN)-alpha and -beta on the expression of thyroid peroxidase (TPO), sodium/iodide symporter (NIS), and thyroglobulin (Tg) as well as T(4) release. Human thyrocyte cultures were carried out with fresh normal thyroid tissue. Gene and protein expression of Tg, TPO, and NIS were assessed by RT-PCR and Western blot analysis after 24, 48, and 72 h of treatment with TSH alone (10 mIU/ml) and in combination with IFN alpha or -beta (10(4) U/ml). IFN inhibited the TSH-stimulated gene expression of Tg, TPO, and NIS in a time-dependent manner without significant differences between IFN alpha and -beta. Moreover, the addition of both type I IFNs clearly reduced the TSH-stimulated protein expression of Tg, TPO, and NIS after 72 h of exposure. Finally, this down-regulation was associated with a reduction of T(4) release by almost 50%. In conclusion, our study shows that both IFN alpha and -beta down-regulate the TSH-stimulated expression of Tg, TPO, and NIS as well as T(4) release. Indeed, the development of hypothyroidism during type I IFN therapy may be related, at least in part, to an abnormal expression and function of key proteins involved in iodine uptake and organification.

Cells, Cultured↗

Non-esterified fatty acids impair insulin-mediated glucose uptake and disposition in the liver.

AIMS/HYPOTHESIS: We investigated the effect of elevated circulating NEFA on insulin-mediated hepatic glucose uptake (HGU) and whole-body glucose disposal (M) in eight healthy male subjects. METHODS: Studies were performed using positron emission tomography (PET) and [(18)F]-2-fluoro-2-deoxyglucose ([(18)F]FDG) during euglycaemic hyperinsulinaemia (0-120 min) and an Intralipid/heparin infusion (IL/Hep; -90-120 min). On a different day, similar measurements were taken during euglycaemic hyperinsulinaemia and saline infusion (SAL). Graphical and compartmental analyses were used to model liver data. RESULTS: Circulating NEFA increased approximately three-fold during IL/Hep, and declined by 81+/-7% in the SAL study ( p</=0.01). Both M (-28+/-7%) and HGU (-25+/-9%) were significantly lowered by NEFA elevation ( p=0.004 and p=0.035 respectively). In the whole data set, the decreases in M and HGU were positively correlated ( r=0.78, p=0.038). No evidence of [(18)F]FDG outflow was detected during the scanning time. HGU was correlated with the phosphorylation rate parameter ( r=0.71, p=0.003) as derived by compartmental modelling. CONCLUSIONS/INTERPRETATION: In healthy men, NEFA impair insulin-mediated HGU and whole-body glucose uptake to a similar extent. Our data suggest that multiple intracellular NEFA targets may concur to down-regulate glucose uptake by the liver.

Adult↗

Beta cell function and its relation to insulin action in humans: a critical appraisal.

The importance of both insulin resistance and beta cell dysfunction in the pathogenesis of glucose intolerance is widely recognised. Also popular is the concept that beta cell secretory function must be viewed in the context of extant insulin resistance. This For Debate moves from the premise that, whilst insulin action in vivo can be measured directly by a variety of essentially coherent techniques, measurement of beta cell function is more problematic. We therefore concisely survey the principal in vivo techniques that explore the diverse aspects of beta cell function and conclude that: (i) inter-correlation of clinical tests is only modest in non-diabetic subjects and poor in diabetic individuals; (ii) no single clinical test allows beta cell function to be assessed with accuracy and specificity comparable to those of insulin sensitivity; and (iii) short of complex experiments, mathematical modelling is necessary to interpret insulin secretory responses. Next we discuss the hyperbola paradigm used to describe the reciprocal relation of beta cell function to insulin sensitivity and suggest that: (i) insulin responses reflecting the basal beta cell tone are indeed inversely related to insulin action across degrees of glucose intolerance; (ii) modes of beta cell function that selectively reflect the dynamic response to acutely changing glucose concentrations are largely independent of insulin action; and (iii) when measured by experiment or resolved by modelling, quantitatively the most important of these dynamic secretion parameters is the glucose dose-response curve (glucose sensitivity). In fact, glucose excursions following glucose ingestion (i.e. glucose tolerance) are best explained by dynamic parameters of beta cell function.

Diabetes Mellitus↗

The EGIR-RISC STUDY (The European group for the study of insulin resistance: relationship between insulin sensitivity and cardiovascular disease risk): I. Methodology and objectives.

AIMS/HYPOTHESES: Insulin resistance is thought to be a key predictor for the development of Type 2 diabetes mellitus and cardiovascular disease (CVD), a leading cause of morbidity and premature mortality in Europe. Insulin resistance is influenced by both genetic and lifestyle factors (e.g. obesity and physical inactivity). The RISC (Relationship between Insulin Sensitivity and Cardiovascular disease) Study is using the infrastructure of an extended European collaborative research group to study insulin resistance and CVD risk in 1500 healthy people aged 30 to 60 years from 20 centres in 13 countries. METHODS: Baseline measurements of glucose tolerance and insulin sensitivity are made by the oral glucose tolerance test and the euglycaemic insulin clamp, respectively; carotid artery intima-medial thickness (by ultrasound), ankle/brachial pressure index and electrocardiography will enable evaluation of subclinical CVD at baseline and at follow-up. Classic CVD risk factors, as well as socioeconomic and lifestyle factors will be recorded at baseline; samples for measurement of biochemical and genetic markers will be collected and stored for future analyses. Investigations will be repeated after 3 and 10 years to evaluate the relationship between insulin resistance and the development of atherosclerosis as measured by carotid artery intima-media thickness. Development of Type 2 diabetes, dyslipidaemia, obesity, hypertension and cardiovascular events are additional endpoints. CONCLUSIONS: This study will evaluate the importance of insulin resistance in the development of CVD and diabetes, and has implications for the development of prevention and treatment strategies.

Adult↗

Thyroid autoimmunity and dysfunction associated with type I interferon therapy.

Type I interferons are currently used for the treatment of chronic viral hepatitis, multiple sclerosis and several hematological and solid tumors. Side effects are not uncommon, and include multiple alterations in thyroid function, some of which are unrelated to autoimmunity. Review of the literature revealed an overall mean prevalence of incident thyroid dysfunction of 6.2%, hypothyroidism occurring more frequently (3.9%) than hyperthyroidism (2.3%). Destructive thyroiditis characterized by early transient thyrotoxicosis followed by hypothyroidism has also been described. Thyroid dysfunction was mainly subclinical, and spontaneous resolution occurred in almost 60% of patients with or without withdrawal of interferon. Risk factors for developing thyroid abnormalities were female sex and the presence of pre-existing autoimmune thyroiditis. Whether prolonged interferon therapy will increase the likelihood of experiencing thyroid dysfunction, as well as the relationship between incident thyroid autoimmunity and the efficacy of interferon therapy, are still open questions. Although the most-likely explanation for thyroid disease occurring with type I interferon therapy remains an autoimmune reaction or immune system dysregulation, a direct inhibitory effect on thyrocytes may be presumed in patients who developed hypothyroidism without autoimmunity. However, the mechanisms of thyroid damage induced by type I interferons have not yet been clarified in detail. We recommend routine evaluation of serum thyroid-stimulating hormone during interferon therapy. A systematic thyroid assessment is useful only for those patients with pre-existing thyroiditis or incident dysfunction. Although discontinuation of interferon therapy is seldom required, it may be necessary in patients who develop Graves' disease and overt hyperthyroidism.

Autoimmune Diseases↗

Thyroid involvement in patients with overt HCV-related mixed cryoglobulinaemia.

BACKGROUND: Mixed cryoglobulinaemia (MC), a systemic vasculitis associated with hepatitis C virus (HCV) infection in >90% of cases, is frequently complicated by multiple organ involvement. The prevalence of thyroid disorders in MC has not yet been studied. AIM: To investigate the prevalence and clinical features of thyroid involvement in patients with HCV-associated MC (HCV + MC). DESIGN: Case-control study. METHODS: HCV + MC patients (n = 93, 17 men and 76 women, mean +/- SD age 63 +/- 10 years, mean disease duration 14 +/- 7 years) consecutively referred to the Rheumatology Unit were matched by sex and age (+/- 2 years) to (i) 93 patients with chronic C hepatitis (CH) without MC and (ii) 93 healthy (HCV-negative) controls from the local population. Measurements included prevalence of hypo- or hyperthyroidism, thyroid autoantibodies, thyroid nodules and thyroid cancer. RESULTS: By McNemar's chi(2) test, the following thyroid abnormalities were significantly more frequent in HCV + MC patients than in HCV-negative controls: serum anti-thyroperoxidase autoantibody (AbTPO) (28% vs. 9%, p = 0.001); serum AbTPO and/or anti-thyroglobulin autoantibody (31% vs. 12%, p = 0.004); subclinical hypothyroidism (11% vs. 2%, p = 0.038); thyroid autoimmunity (35% vs. 16%, p = 0.006). Serum AbTPO were also significantly more frequent in HCV + MC patients than in CH controls (28% vs. 14%, p = 0.035). DISCUSSION: The prevalence of thyroid disorders is increased in patients with HCV-related mixed cryoglobulinaemia. We suggest careful monitoring of thyroid function in these patients.

Aged↗

Lipoprotein lipase gene variants and progression of nephropathy in hypercholesterolaemic patients with type 2 diabetes.

OBJECTIVE: Recent prospective studies have identified hyperlipidaemia as an independent determinant of diabetic nephropathy. Lipoprotein lipase (LPL) is a key enzyme in the postprandial processing of triglycerides and VLDL. Among a number of common sequence variants of the LPL, HindIII has been associated with coronary heart disease and, more recently, with microalbuminuria in type 2 diabetes. We evaluated the progression of renal disease in hypercholesterolaemic type 2 diabetic patients in relation to this polymorphism. DESIGN AND SUBJECTS: We followed up for 4 years 65 consecutively enrolled microalbuminuric patients with type 2 diabetes; of whom 28 had hypercholesterolaemia (6.62 +/- 0.9 mmol L(-1), group A) and 37 were normocholesterolaemic (4.68 +/- 0.5 mmol L(-1), group B). MAIN OUTCOME MEASURES: After performing the genetic analyses, albumin excretion rate (AER) and estimated glomerular filtration rate (GFR), calculated by the simplified equation of the MDRD Study Group, were repeated every year. RESULTS: In group A, AER increased more (deltaAER: 11 [38] vs. 4 [18] microg min(-1) per year in group B, P < 0.0001) while GFR declined faster (-3.5 +/- 2.1 vs. -2.0 +/- 1.4 mL min(-1) per year, P < 0.02). Patients homozygous for the allele + of HindIII showed a significantly faster decline of GFR and a higher increase of AER (both P = 0.0001) even after adjustment for cholesterol levels and anthropometric variables. CONCLUSIONS: In hypercholesterolaemic type 2 diabetic patients with microalbuminuria, the renal disease has an accelerated course, particularly in those carrying the H+/H+ genotype of the HindIII polymorphism at the LPL locus.

Aged↗

Effect of levothyroxine replacement on lipid profile and intima-media thickness in subclinical hypothyroidism: a double-blind, placebo- controlled study.

Subclinical hypothyroidism (sHT) is associated with dyslipidemia and enhanced cardiovascular risk. We assessed carotid artery intima-media thickness (IMT, high-resolution ultrasonography) and lipoprotein profile in 45 sHT patients (aged 37 +/- 11 yr) at baseline and after 6 months of randomized, placebo-controlled L-T(4) replacement. In comparison with 32 age- and sex-matched controls, sHT patients had elevated total and low-density lipoprotein (LDL) cholesterol and ApoB levels (P = 0.002, P = 0.0007, and P = 0.01, respectively) and higher mean-IMT values (P < 0.0001). In stepwise regression analysis, mean-IMT was positively related (r(2) = 0.71, P < 0.0001) to age, TSH, and LDL cholesterol. L-T(4) replacement significantly reduced both total and LDL cholesterol (P < 0.0001 for both) and mean-IMT (by 11%, P < 0.0001). The decrement in IMT was directly related to the decrements of both total cholesterol and TSH (P = 0.02 and P = 0.0001, respectively). We conclude that early carotid artery wall alterations are present in sHT patients. Whether such IMT increase is related to an early atherosclerotic involvement of the arterial wall cannot be clearly decided on the basis of the present results. However, the fact that L-T(4) replacement therapy was able to improve both the atherogenic lipoprotein profile and intima-media thickening suggests that lipid infiltration of arterial wall may represent a major mechanism underlying IMT increase in subclinical hypothyroidism.

Adult↗