Hormonal fluctuations such as hypothyroidism -- a condition that occurs when your thyroid gland does not produce enough of important hormones -- can indeed be to blame for dandruff flakes. (In fact, patients with an underactive thyroid often suffer from dry, itchy skin not only on their scalps, but on the rest of their body too.)
Weight gain, fatigue and sensitivity to cold are other symptoms of a slow thyroid. If you suspect you might be suffering from the condition, make an appointment with your doctor to have your thyroid level checked. To keep your dandruff in check, be sure to wash your hair every day, alternating your regular shampoo with an over-the-counter dandruff formula.