Introduzione. L’ipovitaminosi D è un fattore di rischio indipendente per mortalità cardiovascolare. In età adulta, bassi livelli di vitamina D sono associati con ipertensione, insulino-resistenza, malattie cardiovascolari, sindrome metabolica e diabete. Nel bambino vi sono tuttora pochi dati sulla relazione tra ipovitaminosi D e fattori di rischio cardiovascolari e metabolici. Scopo. Lo scopo di questa tesi è di valutare in bambini e adolescenti sovrappeso e obesi la relazione tra l’ipovitaminosi D e i principali fattori di rischio cardiovascolare e metabolico, ovvero la presenza di ipertensione, studiata mediante la misurazione pressoria delle 24 ore, la steatosi epatica, le alterazioni del metabolismo glucidico e lipidico. Soggetti e metodi. Sono stati inclusi nello studio 53 bambini obesi e sovrappeso (35 maschi e 18 femmine) di età tra i 7 e i 16 anni, afferenti al dipartimento di Pediatria dell’Università di Verona tra ottobre 2009 e luglio 2010 per accertamenti in merito a obesità. Sono stati esclusi tutti i bambini affetti da malattie croniche, malformazioni o facenti uso cronico di farmaci inclusi preparati contenti vitamina D o supplementi multivitaminici. Tutti i bambini hanno eseguito un prelievo per la misurazione di 25-idrossi-vitamina D (25(OH)D), assetto lipidico, ALT; una curva da carico orale di glucosio (OGTT), un’ecografia epatica e una misurazione pressoria delle 24 ore (ABPM). Risultati. E’stata evidenziata un’ipovitaminosi D nell’81% dei soggetti (deficit di vitamina D (25(OH)D < 20 ng/ml) nel 66% dei casi, valori di vitamina D insufficenti (25(OH)D tra 20 ng/ml e 30 ng/ml) nel 15%). I valori di HOMAIR, e insulinemia a digiuno hanno mostrato una correlazione significativamente negativa con i valori di 25(OH)D, mentre il QUICKI è risultato essere correlato positivamente. Non abbiamo evidenziato correlazioni tra i valori di glicemia, i parametri dell’OGTT e i valori di vitamina D e nemmeno per quanto riguarda i parametri relativi al metabolismo lipidico. Abbiamo evidenziato una differenza significativa in termini di valori pressori sistolici medi notturni durante registrazione ABPM tra i diversi terzili di vitamina D, con valori pressori significativamente più alti per livelli minori di vitamina D. Il blood pressure load (BP load) diastolico delle 24 ore e alcuni parametri pressori notturni, ovvero il BP load diastolico notturno e il blood pressure index (BP index) sistolico notturno sono significativamente più elevati all’aumentare del grado di deficit di vitamina D. I valori di vitamina D inoltre correlano negativamente con la pressione sistolica media e con la pressione sistolica media notturna, con il BP load diastolico, BP load sistolico notturno, BP load diastolico notturno con il BP index sistolico e il BP index sistolico notturno. Non vi sono correlazioni tra i valori di vitamina D e il grado di ipertensione diurno sia quando espresso come BP index che come BP load, ad eccezione del BP load sistolico Conclusioni. Il nostro studio è il primo studio che analizza la relazione tra i livelli di vitamina D e la pressione arteriosa misurata nelle 24 ore in bambini e adolescenti obesi; oltre a confermare quanto noto in letteratura aggiunge importanti informazioni riguardo la relazione tra bassi livelli di vitamina D e valori elevati di pressione arteriosa nella notte. Inoltre abbiamo confermato l’elevata prevalenza di ipovitaminosi D in bambini adolescenti obesi e una correlazione tra la gravità del deficit di vitamina D e l’insulino-resistenza quantificata in termini di HOMAIR. Studi prospettici e trial adeguati saranno utili per analizzare gli effetti sulla pressione arteriosa e sull’insulino-resistenza di un eventuale supplementazione di vitamina D nei bambini e adolescenti obesi.
Introduction. Hypovitaminosis D is an independent risk factor for cardiovascular morbidity. In adults, low levels of vitamin D are associated with hypertension, insulin resistance, cardiovascular disease, metabolic syndrome and diabetes. At present, no data are available about the relationship between cardiovascular and metabolic risk factors and hypovitaminosis D in children. Aim. The aim of this study was to evaluate the relationship between hypovitaminosis D and cardiovascular and metabolic risk factors such as hypertension evaluated with 24-h ABP patterns, hepatic steatosis, dyslipidemia and glucose intolerance in overweight and obese children and adolescent. Subjects and methods. Fifty-three Caucasian children (35 males and 18 females) aged 7-16 yrs were recruited among the overweight and obese children followed at the Department of Paediatrics of the Verona University Hospital, between October 2009 and July 2010. Exclusion criteria were chronic diseases, malformations, chronic use of drugs, including vitamin D or multivitamin supplements. We recorded anthropometric parameters, took blood samples for 25-hydroxivitamin D measurements, total LDL and HDL cholesterol, triacylglycerol, ALT and monitored ambulatory blood pressure (ABP). All children underwent OGTT and hepatic ultrasonography. Results. Hypovitaminosis D was diagnosed in 81% of the study group children (vitamin D deficiency (25(OH)D < 20 ng/ml) in 66% of children, vitamin D insufficiency (25(OH)D between 20 ng/ml and 30 ng/ml) in 15%). Vitamin D levels were negatively correlated with HOMAIR and fasting insulin, and positively with QUICKI. No relationship was found neither between fasting glucose, OGTT parameters and vitamin D levels, or between vitamin D total, LDL, HDL and cholesterol. We found nocturnal systolic pressure to be significantly higher in children with lower values of vitamin D. The 24-h diastolic BP load, the nighttime diastolic BP load and the nighttime systolic BP index increased progressively as the vitamin D deficiency worsened. We found a negative correlation between vitamin D levels and with 24-hour and nighttime systolic BP, 24-h diastolic BP load, nighttime systolic and diastolic BP load, 24-h systolic ABP index and nighttime systolic BP index. No relationship was found between daily diastolic hypertension level, daytime BP index or daytime BP load and vitamin D levels except for diastolic BP load. Conclusions. Our study is the first study that analyzed the relationship between vitamin D levels and 24-h BP patterns in obese children and adolescents; in agreement with previous studies it adds relevant information about the relationship between low vitamin D levels and high nocturnal blood pressure levels. Moreover we found a high prevalence of hypovitaminosis D in obese children and adolescent and a correlation between the severity of vitamin D deficiency and insulin resistance evaluated as HOMAIR. Prospective studies and vitamin D supplementation trials could confirm a cause-effect relationship between vitamin D and BP or insulin resistance also in children/adolescents.
IPOVITAMINOSI D E FATTORI DI RISCHIO CARDIOVASCOLARI E METABOLICI NEI BAMBINI SOVRAPPESO E OBESI
BANZATO, Claudia
2012-01-01
Abstract
Introduction. Hypovitaminosis D is an independent risk factor for cardiovascular morbidity. In adults, low levels of vitamin D are associated with hypertension, insulin resistance, cardiovascular disease, metabolic syndrome and diabetes. At present, no data are available about the relationship between cardiovascular and metabolic risk factors and hypovitaminosis D in children. Aim. The aim of this study was to evaluate the relationship between hypovitaminosis D and cardiovascular and metabolic risk factors such as hypertension evaluated with 24-h ABP patterns, hepatic steatosis, dyslipidemia and glucose intolerance in overweight and obese children and adolescent. Subjects and methods. Fifty-three Caucasian children (35 males and 18 females) aged 7-16 yrs were recruited among the overweight and obese children followed at the Department of Paediatrics of the Verona University Hospital, between October 2009 and July 2010. Exclusion criteria were chronic diseases, malformations, chronic use of drugs, including vitamin D or multivitamin supplements. We recorded anthropometric parameters, took blood samples for 25-hydroxivitamin D measurements, total LDL and HDL cholesterol, triacylglycerol, ALT and monitored ambulatory blood pressure (ABP). All children underwent OGTT and hepatic ultrasonography. Results. Hypovitaminosis D was diagnosed in 81% of the study group children (vitamin D deficiency (25(OH)D < 20 ng/ml) in 66% of children, vitamin D insufficiency (25(OH)D between 20 ng/ml and 30 ng/ml) in 15%). Vitamin D levels were negatively correlated with HOMAIR and fasting insulin, and positively with QUICKI. No relationship was found neither between fasting glucose, OGTT parameters and vitamin D levels, or between vitamin D total, LDL, HDL and cholesterol. We found nocturnal systolic pressure to be significantly higher in children with lower values of vitamin D. The 24-h diastolic BP load, the nighttime diastolic BP load and the nighttime systolic BP index increased progressively as the vitamin D deficiency worsened. We found a negative correlation between vitamin D levels and with 24-hour and nighttime systolic BP, 24-h diastolic BP load, nighttime systolic and diastolic BP load, 24-h systolic ABP index and nighttime systolic BP index. No relationship was found between daily diastolic hypertension level, daytime BP index or daytime BP load and vitamin D levels except for diastolic BP load. Conclusions. Our study is the first study that analyzed the relationship between vitamin D levels and 24-h BP patterns in obese children and adolescents; in agreement with previous studies it adds relevant information about the relationship between low vitamin D levels and high nocturnal blood pressure levels. Moreover we found a high prevalence of hypovitaminosis D in obese children and adolescent and a correlation between the severity of vitamin D deficiency and insulin resistance evaluated as HOMAIR. Prospective studies and vitamin D supplementation trials could confirm a cause-effect relationship between vitamin D and BP or insulin resistance also in children/adolescents.File | Dimensione | Formato | |
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