Hi can you tell me why I have had the symptoms of hyperthyroidism on and off for the past 8 years yet every time I have a blood test there is no sign of it. Symptoms include massive hair loss, extreme tiredness, moodiness, fraying nails, dry hair and skin, depression, very cloudy thinking and forgetfulness. Had half my thyroid removed in 2005 because it had quite a large mass in it and I have not felt right ever since. Thanks Johanne