The specific temperature numbers in various accounts should be understood as estimates and approximations rather than confirmed measurements.

Cold Kills Twice — The Second Danger

One of the aspects of severe hypothermia that gets less attention in popular accounts of cases like Jean Hilliard’s is the danger that doesn’t come from the cold itself, but from the rewarming.

In the hours and days after a severe hypothermia patient begins to recover, the returning circulation carries a complex mixture of metabolic byproducts from tissues that have been deprived of adequate blood flow for an extended period.

The kidneys, in particular, face a substantial challenge during rewarming: the myoglobin released from damaged muscle tissue, combined with the metabolic debris of hypothermia and the physiological challenge of restored blood flow, can overwhelm kidney function in ways that produce acute kidney injury or kidney failure.