title: Diurnal weight gain as a predictor of serum sodium concentration in patients with psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome).
abstract: Ten male patients (mean age 37.3 +/- 6.4 years) with psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome) underwent measurement of weight, sitting and standing blood pressure, and serum sodium concentration at 7 a.m. and 4 p.m. weekly for 8 consecutive weeks. Blood pressure was higher in the afternoon than in the morning. The diurnal decrease in serum sodium (141.4 +/- 2.8 to 134.2 +/- 4.8 mEq/l) was associated with a diurnal increase in weight (78.4 +/- 9.7 to 80.0 +/- 10.3 kg). When the weight increase was normalized by dividing by 7 a.m. weight (NDWG), the following relationship evolved: diurnal serum sodium decrease = 3.060 + [201.728 x NDWG]. Therefore, NDWG accounted for 63.1% of the variability of serum sodium. Using the known relationship of plasma water, total body water, and total body weight, we calculated that antidiuresis (afternoon weight gain) accounted for 62.5% of afternoon hyponatremia. Thus, two separate methods of calculating the relationship between antidiuresis and hyponatremia provided remarkably similar findings. We derived a table to predict 4 p.m. serum sodium values based on 7 a.m. weight, 7 a.m. serum sodium, and 4 p.m. weight.
authors.affiliation: Western State Hospital, Department of Health and Mental Retardation, Commonwealth of Virginia, Staunton 24401.
authors.forename: W V
authors.initials: WV
authors.lastname: Vieweg
authors.forename: P L
authors.initials: PL
authors.lastname: Hundley
authors.forename: L S
authors.initials: LS
authors.lastname: Godleski
authors.forename: D A
authors.initials: DA
authors.lastname: Tisdelle
authors.forename: T
authors.initials: T
authors.lastname: Pruzinsky
authors.forename: G R
authors.initials: GR
authors.lastname: Yank
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000523:psychology; D002940:Circadian Rhythm; D004326:Drinking; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000523:psychology*; D008297:Male; D011618:Psychotic Disorders / Q000097:blood / Q000523:psychology*; D012565:Schizophrenic Psychology; D012964:Sodium / Q000097:blood*; D013577:Syndrome; D015430:Weight Gain
chemical_list: D012964:Sodium