Colloid goitre is a common condition world wide. A recent study has shown that, on ultrasound, 4% US population has goitre. Some populations such as living in subhimalayan region has very high prevalence. But situation is changing now with the Universal Iodization Programme.
The most common cause of this problem is Iodine deficiency sometime in life. Implications are not grave as most of the people with colloid goitre have no symptoms and thyroid functions (TSH, T3 and T4 are normal. Chances of malignancy are very very less. Only thing required is periodic examination of size of gland by Ultrasound (once in 2-3 years) and TSH levels once in a year. So please do not worry about these benign nodules in your thyroid gland.