Howard LeWine, M.D., is chief editor of Internet Publishing at Harvard Health Publications. He is recognized as an outstanding clinician and teacher and is a recipient of the Internal Medicine Teacher of the Year award at Brigham and Women's Hospital. Dr. LeWine continues to practice Internal Medicine; most recently he became a hospitalist after practicing primary care for over 20 years.
Question:
My TSH level was 59.214. My doctor decreased the Synthroid dose from .75 to .25. Should it have been increased if my thyroid is underactive?
Answer:
Take a closer look at your prescription labels. I suspect that your prior dose was 0.075 milligram (or 75 micrograms) and that the new dose is actually higher. Synthroid (and other generic L-thyroxin preparations) comes in many doses (the numbers below are in micrograms):
-
25
-
50
-
75
-
88
-
100
-
112
-
125
-
137
-
150
-
175
-
200
-
300
Since there is no pill that has 0.75 milligram (or 750 micrograms, which is a very high dose), I suspect that your new prescription is for 0.125 milligrams (or 125 micrograms), or perhaps a slightly higher dose.
TSH, short for thyroid-stimulating hormone, is a small protein secreted by the pituitary gland in the brain that encourages the thyroid gland to make more thyroid hormone. When the thyroid gland doesn't respond, TSH rises in attempt to make a poorly functioning or non-functioning thyroid gland work harder. High values of TSH confirm a diagnosis of an underactive thyroid (hypothyroidism).
So your assumption is correct, you do need a higher dose. I am sure that this is what your doctor intended. Recheck both labels first. If the label on the new prescription does show a lower dose than before, contact the pharmacy to make sure there was no error when the prescription was filled. If the pharmacy filled it according to what the doctor ordered, call your doctor today to get the dose adjusted.