Section1

Recommended TSH Ranges

According to AACE, serum TSH levels should range from 0.45 to 4.12 mIU/L. NACB recommends TSH levels in the blood should be in the range of 0.5 to 2.0 mIU/L. A TSH test can help initially test thyroid function.^1-3

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Abbreviations: AACE, American Association of Clinical Endocrinologists; NACB, National Academy of Clinical Biochemistry.

NOTE: Values on horizontal axis are not equal. TSH levels alone may not be diagnostic of a thyroid disorder. Additional laboratory testing and clinical findings may be necessary.

Section2

Additional dosages available.

Individualized Dosing

The standard treatment for hypothyroidism is levothyroxine therapy, which must be tailored to each individual patient. The ATA/AACE guidelines advocate the use of a consistent levothyroxine preparation for individual patients to minimize variability from refill to refill.¹

Keep in mind, levothyroxine is a narrow therapeutic index (NTI) medication, meaning small differences in dose or blood concentration may lead to dose- and blood concentration-dependent serious therapeutic failures or adverse drug reactions. The FDA cautions that NTI drugs often must be adjusted in small increments because of potential adverse reactions associated with sub- or supratherapeutic drug concentrations.⁴

Section3

Finding the Right Dose

Under- or overtreatment can have a serious effect on some patients. Successful management of hypothyroidism requires very specific and individualized patient dosing.^1,5

Learn more about narrow therapeutic index (1:50)

Section4

Monitoring Dosage and TSH Levels

Finding the right dose for patients can take time. Be sure to monitor TSH levels regularly until the patient is within a normal range.

The ATA and AACE recommend that patients undergo reassessment and therapy should be titrated at 4-8 weeks after initiating treatment, or following any change in levothyroxine dose.¹

To ensure ongoing success with treatment, patients’ TSH levels should be continuously monitored. Once the TSH level is in the normal range, the frequency of visits can be decreased. Although each patient’s care must be individualized, a follow-up visit should be scheduled in 6 months and then annually.¹

Learn more about TSH levels (1:34)

References:

Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012;18(6):989-1028.
Demers LM, Spencer CA, eds; National Academy of Clinical Biochemistry. Laboratory medicine practice guidelines: laboratory support for the diagnosis and monitoring of thyroid disease. https://www.aacc.org/~/media/practice-guidelines/thyroid-disease/thyroidarchived2010.pdf?la=en. Published 2002. Accessed May 9, 2016.
Thyroid function tests. American Thyroid Association website. http://www.thyroid.org/thyroid-function-tests/. Accessed March 21, 2016.
Yu LX, Jiang W, Lionberger R, et al. Novel bioequivalence approach for narrow therapeutic index drugs. Clin Pharmacol Ther. 2015;97(3):286-291.
Braverman LE, Cooper DS, eds. Werner and Ingbar's The Thyroid. A Fundamental and Clinical Text. 10th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.