Jodthyrox

Jodthyrox is a combination product that contains levothyroxine (thyroid hormone T4) and potassium iodide (iodine). It is used to treat goiter caused by iodine deficiency.

Germany is considered an iodine-deficient region. Iodine is an essential building block for the production of the thyroid hormones T3 and T4. If the thyroid receives too little iodine, it cannot produce enough hormones.

Jodthyrox combines direct hormone replacement (levothyroxine) with iodine supply (potassium iodide) in one tablet.

The product contains two components.

Levothyroxine (T4) is the synthetically produced form of the hormone that the thyroid mainly makes. The body converts it into active T3 as needed. It replaces missing thyroid hormone.

Iodide is the building block from which the thyroid makes its own hormones. If iodine is lacking, the thyroid cannot produce enough and grows — a goiter develops.

The combination is intended for the treatment of simple goiter without a functional disorder when additional iodine alongside the hormone is advisable — and for preventing a goiter from recurring after surgery. The hormone takes work off the thyroid and thus slows the growth stimulus, while the iodide corrects the deficiency.

Treatment is usually planned for one to two years. After that, it is usually continued with iodide alone, provided the diet does not supply enough iodine.

Whether this combination is suitable in the individual case is decided by the medical review based on blood test results and an examination of the thyroid. In thyroid autonomy, additional iodine can trigger hyperthyroidism — that is why this must be clarified beforehand.

Jodthyrox is suitable for:

• Goiter (enlarged thyroid) caused by iodine deficiency
• Goiter prevention after thyroid surgery (partial resection)
• Euthyroid goiter (enlarged thyroid with normal function)

Not suitable for:

• Hashimoto's thyroiditis (iodine can worsen the autoimmune reaction!)
• Hyperthyroidism
• Thyroid autonomy (hot nodules)
• Iodine allergy

Available strength:

• 100 mcg levothyroxine + 131 mcg potassium iodide (equivalent to 100 mcg iodine)

Dosage:

• Usually 1 tablet daily
• Dose adjustment possible by combining with additional L-thyroxine
• Individual adjustment based on the TSH level

• Once daily in the morning, on an empty stomach, at least half an hour before breakfast, with a glass of water.
• The interval before the meal is important: food, especially coffee, milk and soy products, reduces absorption.
• The dose is set by the doctor and increased slowly.
• Do not change or stop it on your own. The effect builds up over weeks.

Intervals from other medicines

• At least two hours from products containing calcium, magnesium or iron, and from heartburn medicines.
• At least four to five hours from colestyramine and similar medicines.

Before thyroid examinations — scintigraphy, radioiodine test or radioiodine therapy — and before examinations with iodine-containing contrast media, the product must be stopped in good time. The timing should be set by a doctor.

Monitoring: After every dose change, blood levels should be checked, usually after six to eight weeks.

Do not use in case of:

• Hypersensitivity to any of the ingredients.
• Hyperthyroidism of any origin — including hyperthyroidism that is not yet noticeable (latent).
• Thyroid autonomy, whether focal or diffuse — even with small autonomous areas, additional iodine can trigger hyperthyroidism.
• Untreated adrenocortical insufficiency.
• Untreated dysfunction of the pituitary gland with adrenal involvement.
• Recent heart attack, acute inflammation of the heart muscle, acute inflammation of all layers of the heart wall.
• Dermatitis herpetiformis Duhring.
• A specific type of blood vessel inflammation (hypocomplementemic vasculitis).

To be clarified with a doctor: coronary heart disease, heart failure, heart rhythm disorders, high blood pressure, older age, kidney disease, and a planned examination or treatment of the thyroid.

Not for weight loss. With normal thyroid function, higher doses can cause serious, even life-threatening side effects.

With a correctly adjusted dose, side effects are rare. If they occur, they are usually signs of a hormone dose that is too high — the body reacts as it would to hyperthyroidism:

• Palpitations, fast or irregular pulse
• Inner restlessness, nervousness, trembling
• Sleep disturbances
• Increased sweating, sensitivity to heat
• Weight loss despite unchanged eating habits
• Diarrhea
• Headache, muscle weakness

Additionally possible due to the iodine component

• In case of iodine hypersensitivity: fever, skin rash, itching, burning eyes, irritating cough, diarrhea, headache — in that case, stop taking it and have it checked by a doctor
• With excessive iodine intake: metallic taste, irritation of the mucous membranes (runny nose, conjunctivitis), acne-like skin changes
• Triggering of hyperthyroidism, especially with pre-existing autonomy or in older people with nodular goiter

Have it checked by a doctor immediately in case of: persistent racing heart, heart rhythm disorders, swelling of the face or throat, shortness of breath.

Absorption of the hormone is reduced by: products containing calcium, magnesium or iron, heartburn medicines, acid blockers (proton pump inhibitors), colestyramine, colestipol, sevelamer, sucralfate, orlistat, coffee taken too close to the dose, and soy-containing food. Semaglutide (weight-loss injection) increases absorption by about one third — with simultaneous treatment, levels should be monitored more closely.

Speed up the breakdown: carbamazepine, phenytoin, phenobarbital, rifampicin.

Additionally to be considered because of the iodine component:

• Medicines for hyperthyroidism (thiamazole, carbimazole, propylthiouracil): iodine can weaken their effect.
• Lithium: together with iodine, it can promote hypothyroidism and thyroid enlargement.
• Potassium-sparing diuretics: potassium levels can rise.
• Iodine-containing contrast media and iodine-containing disinfectants further increase iodine intake.

The effect of other medicines may change:

• Coumarin-type blood thinners: the tendency to bleed can increase.
• Blood-sugar-lowering medicines and insulin: the requirement may change.

Please list all medicines you take, including non-prescription ones and dietary supplements — many contain iodine. Biotin in dietary supplements can distort the measurement of thyroid levels; mention it before a blood draw.