There is substantial evidence that women throughout life have significantly lower plasma levels of the antidiuretic hormone vasopressin (pAVP) compared to men. The importance of this is not yet fully elucidated, but in relation to the observations of lower pAVP levels, no significant difference in renal response parameters was found. This could be interpreted an increased renal sensitivity in females compared to males. The theory of increased renal sensitivity in females is supported by a few pharmacodynamic studies currently available on this topic. However none of the studies was designed with the purpose of investigate the gender difference.

The aim of this study is to investigate possible gender differences in the renal sensitivity to dDAVP and the effect of age on these differences. This will be done by low dose graded infusion of the synthetic AVP analog dDAVP.

Participants are 80 healthy volunteers equally distributed between four age groups, 8-10 years of age, 16-18 years of age, 25-40 years og age and 65+ years of age.

Inclusion Criteria:

• Healthy
• Normal clinical examination
• Normal residual urine measurements
• Normal urine dip stick
• Informed consent by participant or legal guardian

Exclusion Criteria:

• Smoking, alcohol or drug abuse
• Conditions of importance to the results (endocrinological, renal or cardial)
• Current or previous history of incontinence, bedwetting or nocturia
• Drug use of importance (diuretics, hormone replacement therapy, birth control pills, desmopressin)
• Pregnancy
• Allergy towards dDAVP/desmopressin