Low 25-hydroxyvitamin D concentrations in obese women: their clinical significance and relationship with anthropometric and body composition variables

Obesity is associated with low concentrations of 25-hydroxyvitamin D [25(OH) D]. However, conflicting results have been found regarding the relationship of 25(OH) D with anthropometric and adiposity parameters. The aim of our study was to analyze the association between 25(OH) D and body fat (BF) in a homogeneous cohort of non-obese, obese, and morbidly obese Caucasian women. The study was performed in L'Hospitalet de Llobregat, a city adjacent to Barcelona with a latitude of 41 degrees, 22 minutes, and 5 seconds north.

MATERIALS AND METHODS

Plasma concentrations of 25(OH) D were determined and body composition was evaluated by bioelectrical impedance in a group of 43 women with morbid obesity, 28 non-morbidly obese, and 50 non-obese women matched for age.

RESULTS

Morbidly obese women showed lower 25(OH) D concentrations compared to non-morbidly and non-obese women (37.9+/-16 vs 40.2+/-13 vs 56.7+/-21 nmol/l, p=0.001). Fifty-one percent of morbidly obese women had vitamin D deficiency [25(OH) D<38 nmol/l] compared to 22% of non-obese patients, (p=0.004). In the bivariate correlation analysis 25(OH) D was inversely associated with weight (r=-0.41, p=0.001), body mass index (BMI) (r=-0.432, p=0.001), waist to hip ratio (WHR)(r=-0.40, p=0.001), BF (r=-0.53, p=0001), fat mass (r=-0.44, p=0.0001), fat-free mass (r=-0.35, p=0.001). In the multivariate general linear model analysis, 25(OH) D was associated with season of examination (p=0.001) and was negatively associated with BF (beta=-0.75, p=0.001), after adjusting for age, BMI, and WHR.

CONCLUSIONS

25(OH) D concentrations are associated with body composition variables especially by BF, independently of seasonal variability. Therefore, body adiposity should be considered when assessing vitamin D requirements in obese patients.

IL-18: relationship with anthropometry, body composition parameters, leptin and arterial hypertension

OBJECTIVE

Interleukin-18 (IL-18) is a potent pro-inflammatory cytokine with potential atherogenic properties whose role in human obesity has been recently suggested. The aim of our study was to analyze the physiologic distribution of IL-18 among sexes and all decades of the adult life in a healthy population randomly selected and to study its relationship with anthropometric, body composition measurements and leptin concentrations. We also studied the relationship of IL-18 with smoking and arterial hypertension, known risk factors implicated in atherogenesis.

MATERIALS AND METHODS

One hundred and thirty four men and 127 healthy women were included in the study. Plasma concentrations of IL-18 and leptin were determined in all subjects. Body composition was evaluated by bioelectrical impedanciometry.

RESULTS

IL-18 was distributed similarly in men and women and throughout decades. No significant differences were found in IL-18 between obese and normal-weight men and women according to their body mass index and body fat content. Higher IL-18 concentrations were found in subjects with arterial hypertension. In the bivariate correlation analysis only waist to hip ratio correlated weakly with IL-18 in the whole population (r=0.12, p=0.04). In the multiple regression analysis the relationship between IL-18 and waist to hip ratio lost significance after adjusting for age, sex and body mass index. However, IL-18 remained associated with arterial hypertension (adjusted r2=0.25, p=0.023).

CONCLUSIONS

The lack of correlation between IL-18 with anthropometric, body composition variables and leptin in our healthy population argues against a role of this cytokine in obesity. Moreover, our findings suggest the implication of this interleukin in the atherogenic process induced by arterial hypertension.

[The efficacy of the radioiodine treatment of toxic thyroid adenoma and multinodular goiter]

OBJECTIVE

To investigate the effect of radioiodine therapy of thyroid adenoma (TA) and toxic multinodular goitre (TMG) on function and thyroid volume.

MATERIALS AND METHODS

Prospective study which includes 14 consecutive patients with TA and 15 with TMG treated with radioiodine and followed for two years. The therapeutic dose was fixed at 15 mCi for TA and 150 microCi x g of thyroid tissue/uptakes at 6 h (mean dose: 14.4 +/- 4.1 mCi) for TMG. Thyroid function and echographic thyroid volume were determined before and at 1, 3, 6, 12 and 24 months.

RESULTS

90% of patients with TA and 80% with TMG recovered euthyroidism at the third month. One patient with TA and three with TMG required two doses. The latter patients were the only ones with hypothyroidism at two years. The TA volume decreased from 20 +/- 8.5 ml to 10.4 +/- 8.1 ml at two years (p = 0.004). The extranodular thyroid volume did not change (initial: 16.4 +/- 10.4 ml versus 15.6 +/- 3.8 ml at the second year). The thyroid volume in TMG decreased from 66.5 +/- 28 ml to 39.8 +/- 13.5 ml at two years (p = 0.006). The largest reductions for TA and TMG were 54% and 38%, respectively, within the first six months. Only one patient with TA and another patient with TMG had their volumes transiently increased, lower than 10%.

CONCLUSIONS

Therapy with radioiodine of TA and TMG achieves a rapid recovery of euthyroidism and a gradual decrease in thyroid volume with a low incidence of hypothyroidism, with no additional secondary effects. It has proved to be a valid alternative to surgical therapy.