Essential to proper growth, thyroid hormone deficiency is sometimes a cause of dwarfism and mental retardation. Other problems related to a shortage of thyroid hormone include sluggish metabolism, inflammation, goiters, and nodules. Although less common, the thyroid sometimes produces an overabundance of hormones, causing the body to burn calories too quickly. If thyroid disorders go untreated, they can have adverse affects on reproduction, the heart, and other vital organs and bodily functions.