What should be paid attention to when taking levothyroxine for a long time to treat hypothyroidism?😮😮😮

Levothyroxine is a thyroid hormone drug. It is generally used clinically for the treatment of hypothyroidism, non-toxic goiter, thyroid hormone supplementation after surgical resection of thyroid cancer, and adjuvant treatment of hyperthyroidism with antithyroid drugs. The following will introduce the precautions about the use of levothyroxine.

The basic knowledge of levothyroxine.

In clinical practice, the most commonly used dosage form of levothyroxine is levothyroxine sodium tablets. It is most commonly used as a replacement for patients with hypothyroidism and as an adjunctive treatment for patients with hyperthyroidism.

What are the pharmacological effects of levothyroxine?

One of the main indications for levothyroxine is as an alternative treatment for hypothyroidism. Insufficient synthesis and secretion of thyroid hormone in the body is the main cause of hypothyroidism. Levothyroxine is a synthetic form of tetraiodothyronine (T4). It is converted in the body to the more active triiodothyronine (T3). Thus it will exert the same effect as the thyroxine secreted by the body itself and treat hypothyroidism.

Who are the suitable and contraindicated groups of levothyroxine?

It is generally used in patients with thyroid-related diseases. However, it should be prescribed by a doctor and should not be used by patients on their own. It should be contraindicated in patients with untreated adrenal or pituitary insufficiency, thyrotoxicosis, acute myocardial infarction, acute myocarditis, and acute pancarditis. In addition, it should be used with caution in pregnant and lactating women.

What are the common precautions for levothyroxine?

1. Will long-term use of levothyroxine cause adverse reactions?

Current studies have pointed out that when patients take levothyroxine for a long time, as long as they take it in the correct way and in the right dose, they will not cause adverse reactions. Within certain limits, the human body is able to metabolize thyroxine on its own. This keeps thyroxine from causing adverse reactions. However, if the patient takes levothyroxine in large doses for a long time or takes it by mistake, the patient may experience symptoms of hyperthyroidism such as sweating, insomnia, tremors (especially hand tremors), palpitation, and increased appetite.

2. Why is it not recommended to take soy products together with levothyroxine?

Although it is not recommended to eat soy products while patients are taking levothyroxine, it does not mean that patients cannot eat soy products. Under normal circumstances, patients are not recommended to eat soy products, eggs or milk and other related foods within four hours after taking the medicine. Because they reduce the intestinal absorption of levothyroxine, they affect how well it works. Because these foods reduce the amount of levothyroxine absorbed in the intestine, the dose of levothyroxine may need to be adjusted if the patient starts or stops taking soy products for nutritional supplementation.

3. When is the best time to take levothyroxine?

It is generally recommended that patients take one day's dose of levothyroxine with water half an hour before breakfast every day. It can avoid that when food and levothyroxine are taken at the same time, oily substances or other substances in food will affect the absorption of drugs in the gastrointestinal tract. If patients are unable or have difficulty taking levothyroxine in the morning, they may take it four hours after dinner or at bedtime. However, patients are generally not advised to take levothyroxine at night. It is because levothyroxine is an excitatory hormone. Patients taking levothyroxine at night may affect sleep quality. They may experience adverse effects of poor sleep quality or insomnia.

What are the other precautions for levothyroxine?

In addition to the above precautions, the foods and diseases described below can also affect the body's absorption of levothyroxine. 

• Food: soy foods or their products, grapefruit, iron or calcium-containing foods, milk or their products, tea, coffee, foods that can cause thyroid swelling (such as walnuts, cassava, cabbage, cabbage, rapeseed, etc.), cholesterol unhealthy foods (such as animal offal and butter), high-fat foods (such as cooking oil, walnut kernels, almonds, ham, etc.). Patients should avoid or reduce consumption of these foods. The consumption of these foods should also be separated from the time of taking levothyroxine.
• Diseases: malabsorption syndrome (such as achlorhydria), liver cirrhosis, celiac disease, etc.
• Drug Interactions: Antidiabetic drugs, coumarin derivatives, protease inhibitors (eg, ritonavir, lopinavir), phenytoin, cholestyramine, colestipol, drugs containing aluminum, iron, or calcium ( such as antacids), salicylic acid drugs, dicoumarol, furosemide, clofibrate, orlistat, sevelamer, tyrosine kinase inhibitors (such as imatinib), propylthiouracil, Glucocorticoids, amiodarone, iodine-containing contrast media, beta-sympathomimetics, sertraline, chloroquine, hepatic enzyme inducers (eg, barbiturates, carbamazepine), estrogens.