Bioimpedance spectroscopy for the differential diagnosis of hyponatremia.
BACKGROUND
Hyponatremia is classified according to volume status with the help of physical examination, biochemical measures, urine and serum osmolalities, and echocardiography. Bioimpedance spectroscopy (BIS) has been getting popularity for revealing tissue compositions of various patient groups. The aim of this observational study was to investigate the role of BIS for the differential diagnosis of hyponatremia (ClinicalTrials.gov Identifier: NCT01838759).


METHODS
Personal characteristics of age, sex, weight, height, and blood pressure were recorded. Body composition monitor (BCM) was used for hydration status for each individual. Primary outcome was investigated by the accuracy of volume status measured by BIS.


METHODS
Kappa statistic (K) is a measure of agreement between two sources, which is measured on a binary scale (i.e., condition present/absent). K statistic can take values between 0 and 1: poor agreement: K < 0.20, fair agreement: 0.2.0-0.3.9, moderate agreement: 0.40-0.59, substantial: 0.60-0.79, very good agreement: 0.80-1.00.


RESULTS
Fifty-eight hyponatremia-diagnosed patients, 32 (55.2%) of male with the mean age of 65.2 ± 11 (40-89) years were included. Kappa statistic (K) were very good (K = 0.925) for male (p < 0.00), substantial agreement (K = 0.601) for female (p <  0.002) with the use of BIS for the differential diagnosis of either hypo or hypervolemia in hyponatremic patients compared with gold standard tests which were the combination of echocardiography, serum, and urine osmolality biochemical tests, and physical examination.


CONCLUSIONS
Bioimpedance spectroscopy is a practical and an inexpensive method. This is the first study in the literature showing the role of BIS for the determination of the volume status and differential diagnosis of hyponatremia when compared with echocardiography.
a Nephrology Clinic, Istanbul Education and Research Hospital , Istanbul , Turkey .
Sennur Budak
SB
Kose
b Division of Nephrology , Bulent Ecevit University , Zonguldak , Turkey .
Ender
E
Hur
b Division of Nephrology , Bulent Ecevit University , Zonguldak , Turkey .
Kemal
K
Magden
c Nephrology Clinic, Ataturk State Hospital , Zonguldak , Turkey .
Gursel
G
Yildiz
d Department of Internal Medicine .
Derya
D
Colak
e Department of Cardiology .
Emrah
E
Kucuk
d Department of Internal Medicine .
Bilal
B
Toka
f Department of Family Medicine , and.
Hamdi
H
Kucuk
b Division of Nephrology , Bulent Ecevit University , Zonguldak , Turkey .
Ibrahim
I
Yildirim
g Department of Biostatistics , Bulent Ecevit University , Zonguldak , Turkey , and.
Furuzan
F
Kokturk
h Department of Internal Medicine , Ege University , Izmir , Turkey.
Soner
S
Duman
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D058266:Dielectric Spectroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000097:blood* / Q000175:diagnosis*; D007010:Hyponatremia / Q000097:blood* / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
Bioimpedance spectroscopy; euvolemia; hypervolemia; hyponatremia; hypovolemia