What I will tell you is that several researchers out of the University of Dundee in Australia made a presentation at the Annual Society for Endocrinology BES meeting, held not long ago in Manchester, England. The upshot of their research was that it may be safe for patients taking thyroxine replacement drugs (i.e., Synthroid, Levoxyl, etc.) to take enough of the medication to have a low -- but not suppressed -- thyroid-stimulating hormone (TSH) level.
"This is the first population-based study to show that having slightly lower TSH levels when taking thyroxine replacement is not detrimental to health," Graham Leese, MD, BMSc, consultant in diabetes and endocrinology and honorary reader at Ninewells Hospital and Medical School, University of Dundee, Australia, said in a press release.
This was a fairly sizeable study population of more than 16,000 patients thyroxine replacement drugs between 1993 and 2001. The patients were categorized as
- Raised TSH -- TSH above 4.0
- Suppressed TSH -- TSH less than 0.04
- Low TSH -- TSH less than 0.3
- Patients with raised and suppressed TSH levels had an increased risk for heart disease, heart rhythm disturbances, and bone fractures
- Patients with low TSH levels did not have an increased risk for heart disease, heart rhythm disturbances or bone fractures
This latest finding is a more ammunition for patients to take to doctors who think that any treatment -- as long as it gets you somewhere into the old (and actually outdated and insufficient) TSH normal range of .5 to 5.0 -- is all we need.
Leese, Graham & Flynn, Robert. "Is it safe for patients taking thyroxine to have a low but not suppressed serum TSH concentration?," Endocrine Abstracts (2010) 21 OC5.6, Society for Endocrinology BES 2010, 15 March 2010 - 18 March 2010, British Endocrine Societies. Online
"Low TSH levels may be safe for patients taking thyroxine replacement." Endocrine Today. Posted on March 22, 2010, Online