OBJECTIVE: To study the regulation of antidiuretic hormone (ADH) and atrial 
natriuretic peptide (ANP) in obese and lean women with a swelling syndrome.
PATIENTS: Thirty-four obese women and 12 lean women with a swelling syndrome and 
an abnormal isotopic test of capillary permeability to albumin were 
investigated.
MEASUREMENTS: After 10 nocturnal hours of fluid restriction, subjects were asked 
at 8am to ingest a tap water load of 20 ml/kg within 10 min and to remain 
strictly recumbent until twelve noon on the first day, and to remain standing 
and to walk around until twelve noon on the second day. Free water clearance and 
the cGMP/creatinine and albumin/creatinine ratios were determined hourly in the 
morning.
RESULTS: The total 4 h-urinary volume/ingested water volume ratio was 
significantly lower on the second day both in the lean and the obese patients, 
the differences being slightly larger in the obese patients. The increase in 
free water clearance was significantly less on the second day in the obese 
patients. The increase in cGMP/creatinine ratio was also significantly lower on 
the second day in the obese patients. The maximum level of the urinary 
albumin/creatinine ratio was significantly higher on the second day in the obese 
patients.
CONCLUSION: In obese women with a swelling syndrome: (1) The higher increase in 
the urinary albumin excretion rate after water loading followed by a sustained 
upright position suggests a widespread alteration in capillary function, which 
is also indicated by the isotopic test of capillary permeability to albumin. (2) 
The water load-induced inhibition of ADH secretion and stimulation of ANP 
secretion or ANP activity, more defective in the upright position than in the 
recumbent one, is probably another major contributing factor to orthostatic 
oedema.