Low level of urinary 5-hydroxyindole acetic acid (5 HIAA) in obese children having concomitantly high 3-methoxy-4-hydroxyphenyl glycol (MHPG) excretion.

Eighty six obese children and adolescents (44 males) were screened for urinary 5 HIAA and MHPG, noradrenaline (NA), and adrenaline (A) and the results compared with age- and sex-matched controls. Significantly lower amounts of 5 HIAA were found, by contrast to the significantly higher levels of MHPG. These findings cannot be easily explained but an alteration of the normal equilibrium between the adrenergic and the serotonergic tonus may be circumstantially invoked.