The quick answer is yes, a hypoactive thyroid gland can cause a lower body temperature and more prominently the general feeling of always being cold. It sounds like your daughter also has another prominent symptom of low thyroid in lethargy and feeling tired all the time. I think the combination of these two symptoms warrants at least checking the thyroid gland function. Thyroid hormone is one regulator of the body's metabolism. Having too low thyroid hormone causes fatigue, weight gain, cold intolerance, low heart rate, dry skin, and course hair. It is important to get hormone levels back to normal if they are low. Testing for a hypoactive thyroid gland is done by a blood test for TSH levels. When the thyroid gland isn't working, TSH levels are high. The test is simple and results usually only take a day or two to return. Hypothyroidism is treated by replacing the hormone with levothyroxine. Keep in mind that there are other causes of your daughters symptoms. For example depression
in teenagers can present with lethargy and fatigue. I suggest you schedule an appointment for your daughter with her pediatrician
. He or she can sort out which of these possibilities can account for her symptoms. I imagine that a test for TSH level may be warranted. Good luck.