The presence of edema implies, by definition, an increase in extracellular fluid and its principal mineral constituents, sodium and chloride. "Periodic swelling" identifies a physicopsychologic syndrome which occurs almost exclusively in adult females.1 It is characterized by periodic bouts of swelling and abdominal distention in the absence of demonstrable cardiac, hepatic, or renal disease or abnormalities in serum protein levels. It is often associated with headache, increased irritability, and depression. The symptoms are frequently accentuated by hypokalemia, hypomagnesemia, and postural hypotension secondary to excessive use of diuretics.
Hormones which regulate salt and water balance do so predominantly through their action on the kidney. The secretory regulation of these particular humoral agents is known to be closely related to stimuli which enter the central nervous system.
The antidiuretic hormone, ADH or vasopressin, is an octapeptide which is secreted by neurons which arise in the supraoptic and paraventricular nuclei
Thorn GW. Approach to the Patient With "Idiopathic Edema" or "Periodic Swelling". JAMA. 1968;206(2):333-338. doi:10.1001/jama.1968.03150020049009