An association between an increase in
plasminogen activator inhibitor type 1 (PAI-1) and
obesity, and also between elevated levels of
PAI-1 and the presence of
PAI-1 promoter 4G allele has been described in adults and can contribute to increased risk of
cardiovascular disease. It has also been suggested that in adults a decrease in adiposity has beneficial effects on the haemostatic system. However, less information is available regarding adiposity and fibrinolysis in children. The aim of the present study is to evaluate the effect of
weight loss and the influence of the
PAI-1 promoter 4G/5G genotype on the fibrinolytic system and
lipid parameters in obese children. The clinical groups included 102 obese children and 105 controls of similar age and sex distribution. A significant decrease in fibrinolytic activity due to a significant increase in
PAI-1 antigen and activity levels was observed in the obese children in comparison with the control group. In obese children, no significant differences in
PAI-1 levels between the
PAI-1 4G/5G genotypes were obtained. A significant correlation was observed between
PAI-1 antigenic and functional levels and body mass index (BMI), as well as between
PAI-1 levels and both
triglyceride and
insulin levels. No correlation between
PAI-1 levels and either
cholesterol or
glucose levels was observed. After a three-month period of treatment to reduce weight, an increase in fibrinolytic activity due to a decrease in PAI- levels was observed in the obese children who had reduced their BMI in comparison with the group of obese children who did not show a decrease in their BMI. No significant differences between the two groups with respect to the variations in
tissue type plasminogen activator and
fibrinogen levels were obtained after three months of intervention to reduce weight. A significant correlation was observed between variations in BMI and variations in
PAI-1 levels, and a significant inverse correlation was also observed between previous
PAI-1 levels and variation in
PAI-1 levels. Therefore, the largest decrease in
PAI-1 levels was observed in the obese children with the highest previous
PAI-1 levels. In conclusion, a decrease in BMI in obese children shows a favourable effect on the fibrinolytic system due to a decrease in
PAI-1 levels. However, no influence of 4G/5G genotype on
PAI-1 levels was observed.