Liothyronine sodium, also known as Cytomel or LT3, is a synthetic form of a naturally occurring thyroid hormone. While primarily prescribed for treating hypothyroidism (low thyroid levels), its potential role in weight loss has garnered attention. This article aims to provide a comprehensive overview of liothyronine sodium, its uses, potential side effects, and its efficacy and safety as a weight loss aid.
What is Liothyronine Sodium?
Cytomel contains liothyronine in sodium salt form (also called LT3) which is a man-made form of a naturally occurring hormone produced by our thyroid glands called liothyronine. Liothyronine is a class of medications called thyroid agents. It works by supplying the thyroid hormones normally produced by the body. Liothyronine is used to treat hypothyroidism (a condition where the thyroid gland does not produce enough thyroid hormone). It is also used to treat a goiter (an enlarged thyroid gland) and to test for hyperthyroidism (a condition where the thyroid gland produces too much thyroid hormone).
Uses of Liothyronine Sodium
Liothyronine is commonly used for the following conditions:
- Hypothyroidism: Liothyronine may be used to increase levels of thyroid hormone in the body and treat thyroid deficiency disorders (hypothyroidism). It serves as a replacement hormone therapy for people with low thyroid hormone levels, supplying thyroid hormone to people who do not make enough.
- Thyroid cancer: Taking it tells the thyroid gland to stop producing its own hormones, which can help stop the growth of thyroid cancer.
- To test for thyroid problems
Liothyronine may also be used for other conditions as determined by your health care provider.
Liothyronine Sodium and Weight Loss: Separating Fact from Fiction
Although Cytomel does help with weight loss in people prescribed it for hypothyroidism (low thyroid levels), it is not effective at usual dosages at reducing weight in people with normal thyroid levels. Thyroid hormone should not be used to treat obesity in patients with normal thyroid function. Liothyronine is ineffective for weight reduction in normal thyroid patients and may cause serious or life-threatening toxicity, especially when taken with amphetamines.
Read also: T3: Usage and Risks
The Danger of Misuse
Using high dosages of Cytomel to reduce weight in people with normal thyroid levels is dangerous, not safe, and can be life-threatening. Strokes, seizures, shock, coma and death have been reported in people who have taken higher than recommended dosages of Cytomel. Some symptoms of Cytomel toxicity (overdose), such as confusion, disorientation, or heart changes may not appear until several days after ingestion.
Dosage and Administration
Liothyronine comes as a tablet to take by mouth. It usually is taken once daily. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take liothyronine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Your doctor will probably start you on a low dose of liothyronine and gradually increase your dose not more than once every 1 to 2 weeks.
To control the symptoms of hypothyroidism, you probably will need to take this medication for the rest of your life. Continue to take liothyronine even if you feel well. Do not stop taking liothyronine without talking to your doctor.
Switching from Levothyroxine to CYTOMEL
CYTOMEL has a rapid onset of action and residual effects of the other thyroid preparation may persist for the first several weeks after initiating CYTOMEL therapy. When switching a patient to CYTOMEL, discontinue levothyroxine therapy and initiate CYTOMEL at a low dosage. Gradually increase the CYTOMEL dose according to the patient's response.
Read also: Low Sodium Diet Frozen Dinners
Monitoring TSH and Triiodothyronine (T3) Levels
Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation. Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of CYTOMEL may be evidence of inadequate absorption, poor compliance, drug interactions, or a combination of these factors.
In adult patients with primary hypothyroidism, monitor serum TSH periodically after initiation of the therapy or any change in dose. To check the immediate response to therapy before the TSH has had a chance to respond or if your patient's status needs to be assessed prior to that point, measurement of total T3 would be most appropriate. In patients on a stable and appropriate replacement dose, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient's clinical status.
In pediatric patients with hypothyroidism, assess the adequacy of replacement therapy by measuring serum TSH and T3 levels. For pediatric patients three years of age and older, the recommended monitoring is every 3 to 12 months thereafter, following dose stabilization until growth and puberty are completed. Poor compliance or abnormal values may necessitate more frequent monitoring. Perform routine clinical examination, including assessment of development, mental and physical growth, and bone maturation, at regular intervals.
While the general aim of therapy is to normalize the serum TSH level, TSH may not normalize in some patients due to in utero hypothyroidism causing a resetting of pituitary-thyroid feedback. Failure of the serum TSH to decrease below 20 IU per liter after initiation of CYTOMEL therapy may indicate the child is not receiving adequate therapy. Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of CYTOMEL
Monitor serum T3 levels and maintain in the normal range for Secondary and Tertiary Hypothyroidism.
Read also: Healthy Kidney Diet Guide
Potential Side Effects of Liothyronine Sodium
Liothyronine may cause side effects. weight loss, nervousness, excessive sweating, sensitivity to heat, temporary hair loss (particularly in children during the first months of therapy)
Some side effects can be serious. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. headache, irritability, nervousness, sweating, increased bowel motility, menstrual irregularities
Serious Side Effects
While less common, the most serious side effects of liothyronine are described below, along with what to do if they happen.
- Severe Allergic Reactions: Liothyronine may cause allergic reactions, which can be serious. Stop taking liothyronine and get help right away if you have any of the following symptoms of a serious allergic reaction: Breathing problems or wheezing, Racing heart, Fever or general ill feeling, Swollen lymph nodes, Swelling of the face, lips, mouth, tongue, or throat, Trouble swallowing or throat tightness, Itching, skin rash, or pale red bumps on the skin called hives, Nausea or vomiting, Dizziness, feeling lightheaded, or fainting, Stomach cramps, Joint pain.
- Heart Problems: Liothyronine may cause your heart rate to increase or become abnormal. You may also have chest pain. Your risk may be higher if you are older, have heart problems, or if you take too much liothyronine. Tell your health care provider right away if you notice any of the following: Chest pain or pressure, Fast or abnormal heartbeat, Shortness of breath.
- Weak Bones: Liothyronine may cause your bones to become weaker, leading to reduced bone density (osteopenia). It may also cause a more serious condition called osteoporosis, which can cause your bones to break (fracture) more easily. You may be at a higher risk of this if you take too much liothyronine or if you have gone through menopause. Tell your health care provider if you break a bone, and get a bone mineral density test if one is ordered for you.
Warnings and Precautions
- Allergies to Ingredients: People who are allergic to any of the following should not take liothyronine: Liothyronine, Cytomel, Any of the ingredients in the specific product dispensed.
- Reduced Adrenal Function (Adrenal Insufficiency): You should not take liothyronine If you have reduced adrenal function that is not being treated.
- Cardiac Adverse Reactions in the Elderly and in Patients with Underlying Cardiovascular Disease: Overtreatment with thyroid hormone may cause an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients.
- Myxedema Coma: Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism, and may result in unpredictable absorption of thyroid hormone from the gastrointestinal tract. Use of oral thyroid hormone drug products is not recommended to treat myxedema coma.
- Acute Adrenal Crisis in Patients with Concomitant Adrenal Insufficiency: Thyroid hormone increases metabolic clearance of glucocorticoids. Initiation of thyroid hormone therapy prior to initiating glucocorticoid therapy may precipitate an acute adrenal crisis in patients with adrenal insufficiency.
Drug Interactions
Liothyronine interacts with many other medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before taking liothyronine.
- Slow-release nicotinic acid or a bile acid sequestrant, such as colestipol (Colestid), cholestyramine (Prevalite), or colesevelam (Welchol), which is a medicine to lower cholesterol
- Kayexalate, which is a medicine used to treat high potassium in the blood
- Sevelamer, which is a medicine used to treat high phosphate in the blood
- A hormone, such as estrogen (in birth control pills and hormone replacement therapy) or testosterone
- Methadone, which is an opioid medicine used to treat pain or opioid use disorder
- 5-fluorouracil (5-FU), asparaginase, mitotane, tamoxifen, and certain medicines known as tyrosine kinase inhibitors, which are chemotherapy agents that are used to treat or prevent certain cancers
- A corticosteroid, such as dexamethasone, methylprednisolone, or prednisone, which is a medicine for certain inflammatory conditions
- A salicylate, such as diflunisal or salsalate, which is a medicine used for osteoarthritis or rheumatoid arthritis
- Phenobarbital, which is a medicine that may be used to treat seizures
- A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which are in many prescription and OTC products for pain, swelling, and fever
- Rifampin, which is a medicine used to treat certain infections
- A beta-blocker, such as atenolol (Tenormin), metoprolol (Lopressor, Toprol XL, and others), or propranolol (Inderal LA, Innopran XL), which is a medicine that may be used for certain heart conditions or to lower blood pressure
- Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
- Amiodarone (Pacerone and others), which is a medicine used for an irregular heart rhythm
- A medicine for diabetes
- A blood thinner, which is a medicine used to treat or prevent blood clots
- A tricyclic antidepressant or maprotiline, even if it is not used for depression
- A weight loss medication, such as diethylpropion, phendimetrazine, or phentermine (Adipex-P, Lomaira, Qsymia)
Liothyronine and Levothyroxine Combination Therapy
Although the American Thyroid Association guidelines do not recommend taking Cytomel and Synthroid together, many people who are under the supervision of an internist/endocrinologist do take this combination treatment, prefer it, and have good results on it. Never take this combination without your doctor's advice because it may result in excessive levels of thyroid hormones which can be dangerous.
Liothyronine's effect on weight
l-T3 resulted in significant weight loss [l-T4, 70.6 ± 12.5, vs. l-T3, 68.5 ± 11.9 kg (P = 0.009)] and in a 10.9 ± 10.0% decrease in total cholesterol (P = 0.002), 13.3 ± 12.1% decrease in low-density lipoprotein-cholesterol (P = 0.002), and an 18.3 ± 28.6% decrease in apolipoprotein B (P = 0.018).
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