Home > Endocrine Disorders > Symptoms of Thyroid Disease Get the Flash Player to see this player. Rate: (Click the stars to rate) Published on Nov 01, 2008 by JKFernandes, Views: 6061 Thyroid disease can cause many symptoms. The symptoms depend on whether your thyroid is hyperactive, or under active. Hypothyroidism, an underactive thyroid causes fatigue, weight gain, brittle nails, and constipation. Hyperthyroidism, an overactive thyroid causes weight loss, nervousness, and rapid heart beat. Thyroid disease can also cause infertility, and miscarriages.