From the Guidelines
NP Thyroid and estradiol patches can be used together for patients with both hypothyroidism and menopausal symptoms, with estradiol patches preferred due to their better safety profile and ability to mimic physiological serum estradiol concentrations 1. For hypothyroidism, NP Thyroid (natural desiccated thyroid) typically starts at 30-60 mg daily, taken in the morning on an empty stomach, with dosage adjustments every 4-6 weeks based on TSH levels until reaching the optimal dose. For menopausal symptoms, estradiol patches are usually started at 0.025-0.05 mg/day, applied twice weekly to clean, dry skin on the lower abdomen or buttocks, rotating application sites. When using these medications together, it's essential to take NP Thyroid consistently at the same time each day and apply estradiol patches on schedule. Estrogen therapy may increase thyroid binding globulin, potentially requiring thyroid dose adjustments, as seen in studies on menopausal hormone therapy 1. Regular monitoring of thyroid function (every 6-12 months once stable) and annual gynecological exams are necessary. These medications work differently: NP Thyroid replaces deficient thyroid hormones to regulate metabolism, while estradiol patches provide estrogen to alleviate menopausal symptoms like hot flashes and vaginal dryness. Women with intact uteri using estradiol should also take progesterone to prevent endometrial hyperplasia, a consideration highlighted in the context of hormonal replacement therapy 1. Key points to consider when using NP Thyroid and estradiol patches together include:
- Starting with a low dose of estradiol and gradually increasing as needed
- Monitoring for potential interactions between estrogen and thyroid hormones
- Adjusting thyroid hormone doses as necessary to maintain optimal TSH levels
- Regularly reviewing the patient's overall health and adjusting the treatment plan accordingly, taking into account the latest recommendations on hormonal replacement therapy 1.
From the FDA Drug Label
Increased thyroid-binding globulin (TBG) leading to increased circulating total thyroid hormone, as measured by protein-bound iodine (PBI), T 4levels (by column or by radioimmunoassay) or T 3levels by radioimmunoassay. T 3resin uptake is decreased, reflecting the elevated TBG Free T 4and free T 3concentrations are unaltered. Patients on thyroid replacement therapy may require higher doses of thyroid hormone.
The use of estradiol patches may affect thyroid hormone levels in patients taking NP thyroid. Specifically, estradiol can increase thyroid-binding globulin (TBG), leading to increased circulating total thyroid hormone levels. However, free T4 and free T3 concentrations remain unaltered. As a result, patients on thyroid replacement therapy, such as NP thyroid, may require higher doses of thyroid hormone to maintain adequate thyroid function 2.
- Key points:
- Estradiol increases TBG, affecting total thyroid hormone levels
- Free T4 and free T3 concentrations remain unchanged
- Patients on thyroid replacement therapy may need higher doses of thyroid hormone
- NP thyroid dosage may need to be adjusted when used with estradiol patches
From the Research
NP Thyroid and Estradiol Patch
- NP thyroid is a type of thyroid hormone replacement therapy, and its interaction with estradiol patch is an important consideration in the treatment of hypothyroidism in postmenopausal women 3.
- The use of oral estrogen therapy, such as estradiol, can increase the levels of thyroxine-binding globulin (TBG), which can decrease the free fraction of circulating thyroxine (T4) and increase the T4 dosage requirements in women being treated for primary hypothyroidism 3.
- However, transdermal estradiol patch does not affect TBG levels and would not be expected to alter thyroid function, making it a preferable modality for postmenopausal women who require concomitant treatment with estrogen and thyroid hormone replacement 3.
- The dosage of estradiol patch can vary, with the lowest dose approved by the FDA for prevention of osteoporosis being 0.025 microg 4.
- The management of hypothyroidism usually involves monotherapy with levothyroxine, and the use of NP thyroid or other thyroid hormone replacement therapies may be considered in some cases 5.
- Personalized thyroid hormone replacement therapy is necessary to ensure optimal treatment outcomes in hypothyroid patients 6.
Estradiol Patch and Thyroid Hormone Replacement
- The interaction between estrogen therapy and thyroid hormone replacement is complex, and the use of transdermal estradiol patch may be a preferable option for postmenopausal women who require concomitant treatment with estrogen and thyroid hormone replacement 3.
- The effects of estrogen therapy on thyroid function can vary depending on the type and dose of estrogen used, as well as the individual patient's characteristics 3, 4.
- The use of NP thyroid or other thyroid hormone replacement therapies in combination with estradiol patch requires careful monitoring of thyroid function and adjustment of the dosage as needed 3, 6.