Answer: Increased Central Blood Volume (CBV), Decreased ADH, Increased ANP.
The physiological response to hypothermia is vasoconstriction of peripheral vessels (i.e. the ones in your extremities) in an effort to keep your core body temperature normal, and thus your organs functioning properly. Peripheral Vasoconstriction will increase CBV. Increased CBV will cause an increase in preload, and thus cause an increase in ANP/BNP. ANP/BNP has inhibitory effects on the Renin-Angiotensin-Aldosterone System, resulting in decreased ADH.
Men generally have a higher RBC mass (hematocrit, hemoglobin, etc) and it is thought to be attributed to higher testosterone levels. She has high testosterone so you can assume the same for her. This is in Zanki, so it must be in FA or Pathoma.