Table 2.

Baseline serum concentrations of biomarkers of hydration status by body mass index (BMI) category in long-term care residents recruited from 8 facilities.^a

BMI Category	N	Serum Osmolality (mOsm/kg)		BUNb (mg/dL)	BUN/Crc (mg/dL)
		Mean ± SD	N(%) ≥ 295d	Mean ± SD	Mean ± SD
Underweight (BMI < 18.5)	10	301.4±7.1	9(90.0)	18.7±6.9	21.7±9.6
Normal Weight (BMI 18.5–24.9)	65	300.0±8.0	47(72.3)	22.1±8.7	22.4±7.4
Overweight (BMI 25.0–29.9)	41	298.0±10.1	28(68.3)	21.7±14.8	20.5±7.8
Obese (BMI ≥ 30)	12	293.8±7.8	4(33.3)	16.8±8.1	20.7±8.0

^aSerum biomarkers and BMI available for 128 of 247 enrolled subjects due to limitations of no blood draw (N=115) or amputation (N = 4).

^bBUN=Blood Urea Nitrogen

^cBUN/Cr=Blood Urea Nitrogen/Creatinine

^dCut-point of ≥295 indicates current (≥ 300 mOsm/kg) or impending (295–300 mOsm/kg) dehydration.