Unithroid dosage, forms, and strengths

Unithroid is one of several brand-name versions of levothyroxine sodium, the preferred treatment for underactive thyroid (hypothyroidism). Levothyroxine (Unithroid) is a synthetic version of the thyroid hormone thyroxine (T4). In people with hypothyroidism, daily Unithroid doses provide the missing T4 hormone that the thyroid gland would normally produce. Levothyroxine is also a necessary part of treating certain types of thyroid cancers,, suppressing a hormone that may cause lingering cancer cells to grow after surgery and radiation treatment.

Unithroid forms and strengths

Unithroid is an oral medication taken as a tablet. Because dosing needs to be precise, there are 12 different dosage strengths in small increments. The dosages are measured in micrograms (mcg), 1/1000 of a milligram (mg). 

• Tablet: 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, 300 mcg

Unithroid dosage for adults

Unithroid is used to replace thyroid hormone in people with hypothyroidism and to treat thyroid cancer whose growth is stimulated by thyroid-stimulating hormone (TSH). Doses are individualized according to patient-specific factors.

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Unithroid dosage for hypothyroidism

Doctors most frequently prescribe Unithroid to people who have lower-than-normal levels of thyroid hormone. Because thyroid hormones regulate life processes in every tissue in the body, low thyroid hormone levels can reduce the quality of life and cause health problems. For people with hypothyroidism, daily doses of levothyroxine are meant to replace thyroid hormones not produced by the thyroid gland. 

Unithroid dosing is a very fine art, which may change several times at the beginning of therapy and regularly during treatment. Blood tests that measure TSH and T4 help doctors determine the right dose. When starting Unithroid, the initial doses are typically “full replacement doses,” high enough to equal what a healthy thyroid normally produces, about 1.6 micrograms per kilogram of body weight. However elderly patients or patients with coronary heart disease may initially be started on a lower dose of 12.5 to 25 mcg per day. The doctor will then adjust the doses until blood tests confirm that the blood has normal serum TSH levels. 

• Standard Unithroid dosage for adults: 50-200 mcg taken once daily

• Maximum Unithroid dosage for adults: 300 mcg daily

Unithroid dosage for thyroid cancer

Some thyroid cancers grow in the presence of thyroid-stimulating hormone (TSH), also called thyrotropin. These cancers are called thyrotropin-dependent or well-differentiated thyroid cancer. Treatment typically consists of surgery and radioiodine therapy. Patients are left without a functioning thyroid gland at the end of the process. However, they’ll likely have a few cancer cells remaining. TSH is produced by the pituitary gland. TSH then stimulates the thyroid to make thyroid hormones for the body. When thyroid hormone levels drop after cancer treatment, TSH levels skyrocket. Any remaining cancer cells have the potential to quickly start growing again. Cancer doctors (oncologists) use high-dose Unithroid to shut down TSH production after surgery. The dose of Unithroid will vary based on the risk of the cancer returning, so larger doses are required compared to the doses used for the treatment of hypothyroidism.

Unithroid dosage for children

Children as young as newborns may need Unithroid if they have an underactive thyroid. Children may also need Unithroid for certain types of thyroid cancer. For hypothyroidism, pediatric dosages based on weight and age are well-established for thyroid hormone replacement. Doses will still vary. Like adults, healthcare providers will regularly use blood tests to ensure the dose is accurate. Thyroid cancer is different. Doctors will use whatever dose is necessary for adequate TSH suppression. 

Giving a tablet to a very young child may be difficult or undoable. If that’s the case, parents or caregivers can crush the tablet in a small amount of water to make the dose easier to give. Due to Unithroid having a narrow therapeutic index, it is important to not administer the medication in foods that have the potential to decrease absorption, such as soybean-based infant formula.

Source: DailyMed

Unithroid dosage restrictions

Because levothyroxine affects the entire body, dosage adjustments are required for many different types of medical conditions. These include:

• Cardiac disease or seniors: The starting dose is lowered to 12.5–25 mcg/day, though the eventual dose will be the same as it would be in any adult

• Uncorrected adrenal insufficiency: Do not use

• Pregnancy: Doses usually increase by 30-50%; postpartum doses return to normal after delivery

• Newborns at risk of heart failure: Lower dose to start

• Children at risk for hyperactivity: Lower dose to start and a more gradual increases 

• Renal impairment: No dosage modifications

• Hepatic impairment: No dosage modifications

Unithroid dosage for pets

Dogs and cats get hypothyroidism just like people. The treatment is the same: thyroid hormones, usually levothyroxine. Veterinarians could prescribe human versions of levothyroxine, like Unithroid. In dogs, absorption can vary widely, even among individual dogs, and may require much higher doses than humans. Similar to humans, doses will be based on regular blood test results, but starting doses aren’t standardized. Veterinary-approved medications should be used and given on an empty stomach.

RELATED: How to treat hypothyroidism in dogs

How to take Unithroid

Take Unithroid tablets once per day in the morning on an empty stomach. It’s not complicated, but a few details need to be done correctly to get all the benefits of this medicine:

• Take your medicine as directed. Your dose may need to be changed several times to find what works best.

• Unithroid tablets should be taken in the morning on an empty stomach 30–60 minutes before breakfast.

• If you take calcium supplements, calcium carbonate, iron supplements, or antacids (particularly those containing magnesium or aluminum), take Unithroid at least four hours before or after taking one of these supplements or antacids.

• If you are giving this medicine to a baby or child who cannot swallow the tablet whole:

  • Crush the tablet and mix it with 1 to 2 teaspoons (5 to 10 mL) of water. Do not mix the tablet with another liquid (such as infant formula).

  • Immediately give the mixture to the child using a spoon or dropper. Do not store the mixture for future use.

• Don’t stop taking Unithroid without asking your doctor. 

• Store the medicine in a closed container at room temperature, protected from moisture and light.

Unithroid dosage FAQs

How long does it take Unithroid to work?

A Unithroiddose hits its peak concentration in the blood about two hours after taking a tablet. However, people who are just starting Unithroid therapy won’t feel better right away. Symptom improvement isn’t significantly noticeable until the fourth to sixth week of starting treatment. 

How long does Unithroid stay in your system?

With a half-life of 7.5 days, a dose of Unithroid can last as long as five weeks in the body.

What happens if I miss a dose of Unithroid?

Unithroid doses are taken once per day in the morning. If you forget a dose, you have all day to take the forgotten dose. If it’s the next day, skip the missed dose and take it as scheduled. Do not double the dose to make up for a missed dose. 

How long can you take Unithroid?

People usually take Unithroidfor life. 

How do I stop taking Unithroid?

Do not stop taking Unithroid except under the medical advice of a healthcare provider. The doctor may need to prescribe an adequate substitute before you stop. Even then, not all levothyroxine products are the same, so the ATA/AACE guidelines recommend that doctors do blood tests when switching between levothyroxine products.

What is the maximum dosage for Unithroid?

The maximum Unithroiddosage for an underactive thyroid is 300 micrograms. For thyroid cancer, no maximum dosage has been specified. 

Can you overdose on Unithroid?

People can overdose on Unithroid. This can occur when taking higher than prescribed doses.. People with a healthy thyroid (euthyroid) should never take Unithroidfor any purpose. An overdose or misuse of Unithroidwill cause symptoms identical to those of an overactive thyroid (hyperthyroidism), including increased energy, restlessness, mood swings, anxiety, irritability, and trouble sleeping. A severe overdose can lead to life-threatening consequences such as chest pain, confusion, fast or irregular heartbeat, hallucinations, stroke, or shortness of breath a. Anyone displaying symptoms of hyperthyroidism, whether naturally or because they take too much Unithroid or other levothyroxine products, should seek immediate medical care.

What interacts with Unithroid?

Among prescription drugs, prescribers are most concerned about any drug or drug class that normally increases or decreases thyroid hormone levels. When these drugs are taken with Unithroid, doctors may need to take blood tests more frequently and adjust Unithroiddoses. These drugs include:

• Heparin

• Amiodarone

• Rifampin

• Phenobarbital

• Carbamazepine and phenytoin

• Furosemide

• Estrogen replacement therapy

Before starting a new supplement, over-the-counter (OTC) medication, or prescription medication you should reach out to your healthcare professional to ensure additional blood test monitoring is not needed.

For people taking Unithroid, the main issue involves foods and common drugs or supplements that block the absorption of levothyroxine. You should not eat any of these foods or take these drugs within four hours before or after a Unithroid dose. If you do, you may start feeling symptoms of an underactive thyroid again. These include:

• Grapefruit juice, soybean flour, walnuts, and foods high in dietary fiber

• Calcium supplements

• Iron supplements (particularly ferrous sulfate)

• Fiber supplements

• Antacids, such as magnesium hydroxide

• Proton pump inhibitors 

• The ulcer medication, sucralfate

• Gas reducers like simethicone

• The cholesterol-lowering medications colestipol and cholestyramine

• Orlistat, a drug used for the treatment of obesity

Is it safe to take Unithroid during pregnancy?

Unithroid is typically safe to take during pregnancy. Because of the increased demands of pregnancy, dose adjustments will be required, usually 30% to 50% higher than normal. It is important to have your doctor monitor your thyroid level closely.

Is it safe to take Unithroid when breastfeeding?

Unithroid is typically safe to take while breastfeeding. The risks and benefits of taking Unithroid should be discussed with your healthcare provider.

Sources

• Canine hypothyroidism therapy, AAHA

• Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association, AACE Endocrine Practice

• Levothyroxine and cancer, 70 Years of Levothyroxine

• Pharmacokinetics of total thyroxine in dogs after administration of an oral solution of levothyroxine, Journal of Veterinary Pharmacology and Therapeutics

• Treatment of thyroid cancer, by type and stage, American Cancer Society

• Unithroid levothyroxine sodium prescribing information, NIH National Library of Medicine