Jørgen Frøkiær

We investigated the influence of sex and puberty stage on circadian urine production and levels of antidiuretic hormone [arginine vasopressin (AVP)] in healthy children. Thirty-nine volunteers (9 prepuberty boys, 10 prepuberty girls, 10 midpuberty boys, and 10 midpuberty girls) were included. All participants underwent a 24-h circadian inpatient study under standardized conditions regarding Na(+) and fluid intake. Blood samples were drawn every 4 h for measurements of plasma AVP, serum 17-β-estradiol, and testosterone, and urine was fractionally collected for measurements of electrolytes, aquaporin (AQP)2, and PGE2. We found a marked nighttime decrease in diuresis (from 1.69 ± 0.08 to 0.86 ± 0.06 ml·kg(-1)·h(-1), P