Introduction obesity (OB) is one of the most serious public health problems of the 21 st century, especially associated with complications, among which the predisposition to hypertension. There are conflicting data on the relationship between arginine levels and the presence of hypertension in adults, with almost no data on children.

Material and methods A prospective longitudinal observational study of cohorts. Case = high weight (overweight (BMI>p85) and obese (OB) (BMI>p95)); control = normal weight (BMI p95 respectively Children 6–11 years old, prepubertal (Tanner 1–2) were selected. Exclusion criteria: secondary obesity, other organic disease, chronic intake of drugs or diabetes. Plasma arginine levels were measured by tandem mass spectrometry (mmol/L) at initial recruitment and after 12–15 months. One year follow-up of patients repeating clinical measurements of blood pressure, anthropometry and analytical data (arginine).

Results 100 children, 52% male, with a mean age of 8.6±1.6 years; 71% overweight and overweight (63% obese); 79 children with waist circumference above p90. Arginine has no correlation with any of the analytical parameters or with the percentiles of BP and there is no statistically significant difference between baseline arginine levels according to the presence of insulin resistance, overweight or obesity Patients with high blood pressure at initial moment and after one year follow up have lower levels of plasma arginine (p<0.05). Among patients with a valid measure of BP after one year, 55% have a baseline arginine less than 20 mmol/L and, among them, 59% presented a rise in blood pressure above the 90th percentile (p 0.006), with an odds ratio of 7.22 (1.60–32.46), p 0.006.

Discussion Our work provides evidence that there is an already valuable arginine deficit a few months before a tensional increase above the 90th percentile. Biochemical data are provided that can serve as predictors at an age where there may be reversibility of the ”hypertensive gait” process. These findings may elucidate new pathogenic mechanisms in adult hypertension begins in childhood, especially in the case of overweight patients.