Arterial hypertension and thyroid disorders: what is important to know in clinical practice?

This review describes the pathogenic mechanisms of blood pressure (BP) regulation and long-term control in thyroid disorders. Variations from the euthyroid status affect virtually all physiological systems but the effects on the cardiovascular system are particularly pronounced. Thyroid disorders induce several hemodynamic changes leading to elevated BP as a consequence of their interaction with endothelial function, vascular reactivity, renal hemodynamic and renin-angiotensin system. However, in thyroid disorders, the regulation of BP and the development and maintenance of variable forms of arterial hypertension (HT) are different. Hyperthyroidism results in an increased endothelium-dependent responsiveness secondary to the shear stress induced by the hyperdynamic circulation, and contributes to reduce vascular resistance. Conversely, hypothyroidism is accompanied by a marked decrease in sensitivity to sympathetic agonists with an increase of peripheral vascular resistance and arterial stiffness. Furthermore in animal models, hypothyroidism reduces the endothelium-dependent and nitric oxide-dependent vasodilatation. HT due to thyroid disorders is usually reversible with achievement of euthyroidism, but in some cases pharmacological treatment for BP control is required. In hyperthyroidism, ß-blockers are the first-choice treatment to control BP but when they are contraindicated or not tolerated, ACE-inhibitors or calcium-channel blockers (CCB) are recommended. Hypothyroidism is a typical low rennin HT form showing a better antihypertensive response to CCB and diuretics; indeed in hypothyroidism a low-sodium diet seems further to improve BP control. Randomized clinical trials to compare the efficacy on BP control of the antihypertensive treatment in thyroid disorders are needed.

Moderate alcohol consumption, glucose metabolism and lipolysis: the effect on adiponectin and tumor necrosis factor alpha.

Moderate alcohol consumption has a cardioprotective effect on coronary artery disease. Among the beneficial effects of alcohol, a suppression of the plasma free fatty acid (FFA) concentration has been shown but the mechanism which accounts for this action is not clear. We assessed whether moderate alcohol intake affects plasma adiponectin levels and tumor necrosis factor (TNF)-alpha, two regulators of lipolysis. Oral glucose tolerance tests were performed twice on 22 volunteers: "the alcohol study" and "control study". In the former, red wine was sipped to maintain steady state alcohol concentration. Samples for plasma glucose, insulin, FFA, adiponectin, and TNF-alpha concentrations were obtained. In the latter, tap water was sipped. Insulin action has been assessed by the Oral Glucose Insulin Sensitivity (OGIS) Model. The mean blood alcohol concentration was 5+/-2 mg/dl. No differences were observed between the two studies in the OGIS (406+/-19 ml x min(-1) x m(-2) with alcohol and 402+/-20 without, respectively). Baseline FFA levels were lower in the alcohol study; however, post-glucose inhibition was comparable. No differences in the TNF-alpha and adiponectin responses were observed. A significant correlation was observed between the OGIS index and the fasting adiponectin level (r=0.589, p<0.0001). Moderate red wine intake improves post-glucose FFA profiles but does not modify the plasma concentrations of both TNF-alpha and of adiponectin concentrations: the latter is significantly and positively associated to the insulin action. Further studies are needed to clarify the antilipolytic effect of moderate alcohol intake.

Continuous subcutaneous insulin infusion (CSII) in the Veneto region: efficacy, acceptability and quality of life.

AIM: To study the effect of continuous subcutaneous insulin infusion (CSII) on metabolic control and well-being in patients with Type 1 diabetes. METHODS: Efficacy, safety and interference with everyday life associated with CSII were studied retrospectively in 138 diabetic patients from the Veneto region treated for 7.4 +/- 0.4 years. RESULTS: Glycosylated haemoglobin decreased during the first year of CSII from 9.3 +/- 0.2% to 7.9 +/- 0.1% (P < 0.0001), and then remained unchanged. Serious hypoglycaemia decreased from 0.31 +/- 0.07/year to 0.09 +/- 0.02/year (P < 0.003), as did ketoacidosis (from 0.41 +/- 0.12/year to 0.11 +/- 0.03/year, P < 0.013). During the first year of therapy daily insulin requirement decreased from 49 +/- 1 to 42 +/- 2 U/day (P < 0.0001) and did not change thereafter. The number of out-patient consultations and hospital admissions per year also decreased significantly. CSII was associated with a progressive increase of body weight (P < 0.05) and with 0.2 +/- 0.04 infections/patient per year at the infusion site. Infection was rated as mild in 72%, moderate in 18%, severe in 10%. Patients reported that CSII improved metabolic control (71%), sense of well-being (41%), and allowed more freedom (40%). Quality of life, assessed using the DQOL, after 7 years of CSII was rated as good by patients (score of 73.0 +/- 1.8 on a scale from 0 to 100). CONCLUSIONS: This retrospective analysis suggests that CSII improves metabolic control in Type 1 diabetic patients, reduces hypoglycaemic and ketoacidotic events, is well accepted, allows a good quality of life and decreases out-patient consultations and hospital admissions.

Wall thickening of common carotid arteries in patients affected by noninsulin-dependent diabetes mellitus: relationship to microvascular complications.

This study evaluates the wall thickness of common carotid arteries and the atherosclerotic involvement of the carotid bifurcations in patients with noninsulin-dependent diabetes mellitus (NIDDM), with and without microvascular complications. Seventy subjects affected by NIDDM, and 17 healthy controls were evaluated by means of high-resolution echo-Doppler scan. Twenty-six diabetics (Group A) and complications (overnight proteinuria > 500 mg, background retinopathy, sensory neuropathy), while 44 (Group B) had no complications. The two groups were comparable for age, sex, plasma lipid profile, and smoking habit. Arterial hypertension was present in 15 of 26 (58%) complicated patients (Group A) and in 18 of 44 (41%) uncomplicated patients (Group B). None of the patients had a history of cerebrovascular disease. The authors found that the wall thickness of the common carotid artery was greater and atherosclerotic lesions of the carotid bifurcation were more frequent in diabetic patients with microvascular complications than in uncomplicated diabetics (who had a similar distribution of other risk factors for atherosclerosis) and in nondiabetic controls. These data on the one hand confirm the role of diabetes as an independent risk factor for carotid atherosclerosis and, on the other hand, indicate a correlation between microvascular lesions and early atherosclerosis in diabetes.

[Ischemic hepatitis. Description of 4 cases and review of the literature]. / L'epatite ischemia. Descrizione di 4 casi e revisione della letteratura.

We studied four patients who presented a striking elevation of blood transaminases suggesting acute hepatitis. The post mortem histological examination of the liver revealed centrolobular necrosis that is commonly diagnosed as ischaemic hepatitis. The liver necrosis arose from heart failure which was worsened by an acute anaemia in one patient and by a severe hypoxemia, due to respiratory failure, in another. In three subjects there was evidence of disseminated intravascular coagulation that may be responsible for aggravating the condition of liver hypoxia. The authors also review the literature on the various aspects of ischaemic hepatitis.

Carbohydrate and lipid metabolism in patients with non-insulin-dependent diabetes mellitus: effects of a low-fat, high-carbohydrate diet vs a diet high in monounsaturated fatty acids.

Nineteen patients affected by non-insulin dependent diabetes mellitus (NIDDM), in good glycemic control (fasting plasma glucose 7.2 +/- 0.3 mmol/L, glycosylated hemoglobin 6.3 +/- 0.2%), underwent three isocaloric dietary phases. In phases 1 and 3 the diet was rich in complex carbohydrates (Carbo) whereas in phase 2 it was rich in monounsaturated fatty acids (Mono). Plasma glucose concentrations were 7.1 +/- 0.3 and 7.2 +/- 0.3 mmol/L for the two Carbo phases and 7.5 +/- 0.4 mmol/L for the Mono phase (NS). Plasma total cholesterol values for the Carbo phases were 6.2 +/- 0.2 and 6.4 +/- 0.2 mmol/L, respectively, and 6.5 +/- 0.2 mmol/L on the Mono phase (NS). Similarly, no significant changes were noticed for plasma triglycerides and high-density-lipoprotein (HDL) cholesterol. Thus, both diets were well-tolerated and did not alter glucose homeostasis or worsen plasma lipid concentrations. Consequently, these results suggest that a wider dietary choice can be made available to NIDDM patients without producing unwanted side effects.

[Atrial fibrillation in a cohort of the elderly: etiopathogenic role of occult hyperthyroidism and diagnostic and therapeutic considerations. Results of the CASTEL (CArdiovascular STudy in the ELderly)]. / Fibrillazione atriale in una coorte di anziani: ruolo eziopatogenetico dell'ipertiroidismo occulto e considerazioni diagnostiche e terapeutiche. Risultati dello studio epidemiologico CASTEL (CArdiovascular STudy in the ELderly).

This work was performed in order to evaluate the weight of hyperthyroidism on the genesis of atrial fibrillation in elderly subjects. The data are from the CASTEL (CArdiovascular STudy in the ELderly), an epidemiologic study performed in a town of northern Italy (Castelfranco Veneto), whose 3088 elderly subjects were called and 2254 enrolled for a 7-year intervention trial. From 2224 elderly persons examined in the present study, 90 had atrial fibrillation (AF) as determined by the presence of Minnesota Code 8-3; the other 2134 were used as control population. In the 90 with AF and in the randomly chosen controls, the thyroid function was studied by means of the TRH-test. Taking into consideration an increase of TSH greater than 0.5 or greater than or greater than 1 muUI/ml over the basal value after TRH administration, 5.5% of subjects with atrial fibrillation had a suppressed response (i.e. hyperthyroidism); taking into consideration a peak value of TSH greater than or equal to 2.3 muUI/ml irrespective to the basal value, the prevalence of hyperthyroidism was higher (17.8%), but not different than in control subjects. In conclusion, hyperthyroidism is frequent in elderly subjects but it does not play a role in the pathophysiology of AF. On the contrary, AF may be explained in the majority of cases by concomitant cardiovascular disease, i.e. left atrial enlargement, arterial hypertension, myocardial ischemia, and heart failure.

Radionuclear determination of glomerular filtration rate and renal plasma flow to detect early decrease of renal function in insulin dependent diabetes.

To evaluate the role of renal haemodynamic factors in the pathophysiology of diabetic nephropathy, we determined by radionuclear techniques glomerular filtration rate (GFR) and renal plasma flow (RPF) in 18 patients affected by insulin dependent diabetes mellitus (IDDM) in good metabolic control, with normal blood pressure and plasma creatinine. GFR and RPF measured in the same patients after ten months correlated with proteinuria and duration of diabetes. Our finding of a significant correlation between the decline of RPF and duration of diabetes may support the haemodynamic hypothesis of progression of diabetic nephropathy.