Hypovitaminosis D is independently associated with metabolic syndrome in obese patients.
BACKGROUND
Metabolic syndrome (MS) and hypovitaminosis D represent two of the most diffuse condition worldwide, reaching pandemic proportions in industrialized countries, and are both strongly associated with obesity. This study set out to evaluate the presence of an independent association between hypovitaminosis D and MS in an adult population of obese subjects with/without MS.


METHODS
We recruited 107 consecutive obese subjects, 61 with MS (age(mean±SD) 45.3±13.3 years, BMI(mean±SD): 43.1±8.3 kg/m(2)) and 46 without MS (age: 41.8±11.5, p = n.s., BMI:41.6±6.5 kg/m(2), p = n.s.) comparable for sex, BMI, waist circumference and body fat mass, evaluated by bioimpedentiometry. 25(OH) vitamin D3 levels were measured by colorimetric method. Insulin resistance was estimated by fasting blood insulin, HOMA-IR and ISI.


RESULTS
Serum 25(OH)D3 levels were significantly lower in MS obese patients than in obese subjects without MS (median(range) 13.5(3.3-32) vs 17.4(5.1-37.4), p<0.007). Low 25(OH)D3 levels correlated with glycaemia (p<0.007), phosphate (p<0.03), PTH (p<0.003) and the MS (p<0.001). Multivariate model confirmed that low 25(OH)D3 levels were associated with the diagnosis of MS in obese patients independently from gender, age, serum PTH and body fat mass. After stratifying the study population according to 25(OH)D3 concentrations, patients in the lowest quartile showed a markedly increased prevalence of MS compared to those in the highest quartile (OR = 4.1, CI 1.2-13.7, p = 0.02).


CONCLUSIONS
A powerful association exists between hypovitaminosis D and MS in obese patients independently from body fat mass and its clinical correlates. This indicates that the association between low 25(OH) D3 levels and MS is not merely induced by vitamin D deposition in fat tissue and reinforces the hypothesis that hypovitaminosis D represent a crucial independent determinant of MS.
Department of Internal Medicine and Medical Specialties, Sapienza University of Rome, Rome, Italy.
Ilaria
I
Barchetta
Marzia
M
De Bernardinis
Danila
D
Capoccia
Marco Giorgio
MG
Baroni
Mario
M
Fontana
Antonio
A
Fraioli
Sergio
S
Morini
Frida
F
Leonetti
Maria Gisella
MG
Cavallo
D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002112:Calcifediol / Q000097:blood; D005215:Fasting / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000150:complications; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications; D010281:Parathyroid Hormone / Q000378:metabolism; D010710:Phosphates / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000150:complications
D001786:Blood Glucose; D007328:Insulin; D010281:Parathyroid Hormone; D010710:Phosphates; D002112:Calcifediol