Levothyroxine Dose Adjustment to Optimise Therapy Throughout a Patients Lifetime

Overtreatment or undertreatment with levothyroxine may have negative effects on different systems throughout the human body. So, my job as a thyroid specialist in these patients is to make sure my patient is treated and gets to a point of consistency, because it is a lifelong course of medication. HypothyroidismSYNTHROID® (levothyroxine sodium) tablets, for oral use is indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. Some patients with a normal TSH level and symptom resolution may become symptomatic again with or without a change in TSH.

DRUG INTERACTIONS WITH SYNTHROID

• Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid.
• For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of SYNTHROID dosage adequacy and should not be used to monitor therapy.
• There are certain foods that can interfere with the way SYNTHROID works, particularly we think about high-fiber foods that can interact with the absorption of thyroid medications.
• And SYNTHROID is contraindicated in patients who have uncorrected adrenal insufficiency.

Several studies have shown that the levothyroxine dose requirement is decreased in older individuals 8, 48, 49. However, a recent study suggests that this decreased requirement may be mediated by the changes in weight that may accompany ageing 26. Other important considerations regarding levothyroxine doses in older individuals include bearing age-adjusted TSH reference ranges in mind 50 and avoiding over-replacement that might potentially exacerbate other medical conditions 8. Both of these considerations would lead to targeting of higher TSH values in older individuals (Fig.3).

NP Thyroid

When symptoms reappear without a change in TSH level, the physician should consider nonthyroid etiologies. When there is an accompanying change in the TSH level, especially in a patient who has stayed on a stable dosage for some time, other reasons should be explored before adjusting the levothyroxine dosage. If you become pregnant while taking Synthroid, do not stop taking the medicine without your doctor’s advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby. Certain other medicines may also increase or decrease the effects of Synthroid.

• Causes may include primary gland failure or can be iatrogenic, transient, or central (Table 1).1–4 Central causes, such as low levels of thyroid-stimulating hormone (TSH) and free thyroxine (FT4), are rare.
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• This is very critical, because there are many instances with telephone encounters or other things where patients maybe have prescriptions sent in by my nurse or medical assisting staff, and we need to make sure they understand the importance of this process as well because they are a frontline access to these patients.
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• If the TSH level or symptoms are not improving after two to three cycles of adjustments, referral to endocrinology may be considered after reassessment of the differential diagnosis, patient adherence, and drug-drug or drug-food interactions.

For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of SYNTHROID dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate SYNTHROID dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range. A search of the literature was conducted using the PubMed and CENTRAL (Cochrane) databases. Keywords relating to levothyroxine, hypothyroidism, treatment, levothyroxine dose adjustments, levothyroxine and concomitant conditions, levothyroxine and concomitant medications, and combined treatment with levothyroxine and liothyronine versus levothyroxine were searched. Only reviews and articles providing clinical data, particularly the most recent, were considered.

4 Monitoring TSH and/or Thyroxine (T Levels

Do not store the crushed tablet/water mixture and do not administer it mixed with foods that decrease absorption of levothyroxine, such as soybean-based infant formula. DAW codes are codes a pharmacy uses when filling your patient’s prescription. DAW-1 indicates that substitution is not allowed, based on the prescriber’s preference, and ensures your patient will receive the treatment you prescribe. It also helps your patient pay the lowest possible price for the product you write if it is billed through insurance. It’s very important to remind the patients, in addition to these factors, that they need to check their pills on a consistent basis. Look to see if the tablets have Synthroid embossed on them to ensure they’re getting the right product.

• Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption.
• The second is that Synthroid has a history, as physicians have been treating patients with hypothyroidism with Synthroid for over 65 years.
• ​Inquire whether patients are taking biotin or biotin-containing supplements.
• Once the patient and I have decided that thyroid hormone replacement is necessary, we go over the specific reasons for choosing and writing Synthroid as that replacement therapy.

Most, but not all, levothyroxine products have been determined to be therapeutically equivalent by the FDA. One is that the peak therapeutic effect of levothyroxine at a given dose may synthroid tips not be obtained for 4-6 weeks after medication is ingested. ​Biotin supplementation may interfere with immunoassays for TSH, T4, and T3, resulting in erroneous thyroid hormone test results. Stop biotin and biotin-containing supplements for at least 2 days before assessing TSH and/or T4 levels.

When TSH is low (over-replacement), the daily dosage should be decreased by 12.5 to 25 mcg. When TSH is high (under-replacement), the daily dosage is increased by 12.5 to 25 mcg per day. If the TSH level or symptoms are not improving after two to three cycles of adjustments, referral to endocrinology may be considered after reassessment of the differential diagnosis, patient adherence, and drug-drug or drug-food interactions. For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. The recommended starting daily dosage of SYNTHROID in adults with primary, secondary, or tertiary hypothyroidism is based on age and comorbid cardiac conditions, as described in Table 1.

There are also certain vitamins and supplements that can interfere with the absorption of SYNTHROID. The FDA has determined that certain levothyroxine products are interchangeable. Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption.

Hypothyroid – Levothyroxine Dosing calculator

Tirosint is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … Synthroid is a thyroid medicine that replaces a hormone normally produced by your thyroid gland to regulate the body’s energy and metabolism. Mistaken generic users defined as those who reported taking SYNTHROID but did not have “SYNTHROID” embossed on the pill in a national online survey conducted in 2021 of 1908 adults diagnosed with hypothyroidism and currently taking LT4  products. The importance of writing “Dispense as Written,” or using the state-specific language for SYNTHROID, is something I discuss with my staff as well. This is very critical, because there are many instances with telephone encounters or other things where patients maybe have prescriptions sent in by my nurse or medical assisting staff, and we need to make sure they understand the importance of this process as well because they are a frontline access to these patients. Mistaken generic users defined as those who reported taking SYNTHROID but did not have “SYNTHROID” embossed on the pill in a national online survey conducted in 2021 of 1908 adults diagnosed with hypothyroidism and currently taking LT4 products.

Therefore, in people over the age of 65 years, levothyroxine should be started at a small dose (25–50 μg/daily) and dose titration should be carried out slowly. Routine use of levothyroxine in subclinical hypothyroidism is controversial. Patients on high dosages of levothyroxine (greater than 200 mcg per day) with persistently elevated TSH levels may be nonadherent or have absorption issues attributed to meal timing or other medications1,5,20 (Table 5 and Table 820). Some patients may experience persistent symptoms despite adequate dosing of levothyroxine to a normal TSH level; therefore, other etiologies should be considered and evaluated accordingly (Table 41,2). If the TSH level is abnormal, the clinician should assess patient adherence, evaluate drug-drug interactions, and adjust the levothyroxine dosage every six to eight weeks until the TSH level normalizes (Figure 22,3,5,7,10,20–25).