Table 1.

Physical characteristics in POTS women and controls

Variables	POTS Women (n = 10)		Controls (n = 11)
	EFP	MLP	EFP	MLP
Age (yr)	27 ± 9		33 ± 10
Height (cm)	167 ± 6		166 ± 6
Weight (kg)	67 ± 12	66 ± 12	63 ± 7	64 ± 8
BMI (kg/m2)	24 ± 4	24 ± 4	23 ± 2	23 ± 2
Menstrual Cycle Day (d)	4.0 ± 0.4	20.9 ± 0.9*	3.9 ± 0.5	21.5 ± 0.7*
Estradiol (pg/mL)	33.9 ± 8.3	94.6 ± 54.6*	32.4 ± 8.9	91.8 ± 46.7*
Progesterone (ng/mL)	0.8 ± 0.5	7.2 ± 6.1*†	0.9 ± 0.5	11.1 ± 5.7*
Plasma Volume (mL/kg)	41 ± 5†	41 ± 7†	46 ± 5	46 ± 5
Blood Volume (mL/kg)	63 ± 8	62 ± 9	68 ± 7	68 ± 7
Blood pH	7.39 ± 0.01	7.38 ± 0.01	7.42 ± 0.02	7.41 ± 0.01
Na+ (mmol/L)	139 ± 1	138 ± 1	138 ± 1	138 ± 0.4
K+ (mmol/L)	4.2 ± 0.1	4.3 ± 0.1	4.2 ± 0.1	4.3 ± 0.1
Ca++ (mmol/L)	1.17 ± 0.02	1.15 ± 0.02	1.11 ± 0.02	1.15 ± 0.02
24-h Urine Output (mL)	2390 ± 900	2693 ± 1174	2059 ± 860	2338 ± 799
Osmolality (mOs/kg)	296 ± 121	344 ± 231	366 ± 93	360 ± 105
pH	6.7 ± 0.2	6.6 ± 0.2	6.5 ± 0.2	6.4 ± 0.2
Na+ (mmol/24 h)	185.9 ± 48.6	196.0 ± 72.2	148.2 ± 53.7	169.4 ± 48.8
K+ (mmol/24 h)	65.6 ± 32.2	64.2 ± 26.4	52.4 ± 20.6	56.7 ± 17.5
Ca++ (mmol/24 h)	2.0 ± 1.2	2.1 ± 1.5	1.3 ± 0.7	1.7 ± 0.9

Values are mean ± standard deviation. EFP, early-follicular phase; MLP, mid-luteal phase; BMI, body mass index.

^*P < 0.05 compared to MLP within the same group.

^†P < 0.05 compared to controls during the same menstrual phase.