A large population study published in Archives of Internal Medicine (2000;160:526–534) found that as many as 13 million Americans may have undiagnosed thyroid disease. Among more than 25,000 participants screened, nearly 12% had abnormal TSH levels. About 9.5% were hypothyroid and just over 2% were hyperthyroid. Overall, nearly 10% of participants had a thyroid disorder that had never been diagnosed.
Hypothyroidism was far more common in women and increased steadily with age after 34. The study also noted that even mild reductions in thyroid function can raise cholesterol levels. Based on these findings, the authors estimated that up to 10% of Americans with high cholesterol may have underlying, unrecognized hypothyroidism.
