Euthyrox Special Precautions

Thyroid hormones should not be given for weight reduction. In euthyroid patients, treatment with levothyroxine does not cause weight reduction. Substantial doses may cause serious or even life-threatening undesirable effects, particularly in combination with certain substances for weight reduction, and especially with sympathomimetic amines (see also 'Overdosage').
Before starting therapy with thyroid hormones or before performing a thyroid suppression test, the following diseases or medical conditions must be excluded or treated: coronary insufficiency, angina pectoris, arteriosclerosis, hypertension, pituitary insufficiency or adrenal insufficiency. Thyroid autonomy should also be excluded or treated before starting therapy with thyroid hormones.
When initiating levothyroxine therapy in patients at risk of psychotic disorders, it is recommended to start at a low levothyroxine dose and to slowly increase the dosage at the beginning of the therapy. Monitoring of the patient is advised. If signs of psychotic disorders occurs, adjustment of the dose of levothyroxine should be considered.
Even slight drug-induced hyperthyroidism must be avoided in patients with coronary insufficiency, heart failure or tachycardiac arrhythmias. Hence frequent checks of thyroid hormone parameters must be made in these cases.
The aetiology of secondary hypothyroidism must be determined before thyroid hormone replacement therapy is given. If necessary replacement treatment of a compensated adrenal insufficiency must be commenced.
Where thyroid autonomy is suspected, a TRH test or a suppression scintigram is recommended before initiation of treatment.
Haemodynamic parameters should be monitored when levothyroxine therapy is initiated in very low birth weight preterm neonates as circulatory collapse may occur due to the immature adrenal function.
In postmenopausal women with hypothyroidism and an increased risk of osteoporosis supraphysiological serum levels of levothyroxine have to be avoided. Therefore, close monitoring of the thyroid function is recommended.
Levothyroxine is not recommended in hyperthyroid metabolic states. An exception is the concomitant supplementation during anti-thyroid drug treatment of hyperthyroidism.
If a switch to another levothyroxine-containing product is required, there is a need to undertake close clinical monitoring, which may include a laboratory test, during the transition period due to a potential risk of thyroid imbalance. In some patients, a dose adjustment could be necessary.
Hypothyroidism and / or reduced control of hypothyroidism may occur when orlistat and levothyroxine are co-administered (see 'Interactions'). Patients taking levothyroxine should consult a doctor before starting treatment with orlistat, as orlistat and levothyroxine may need to be taken at different times and the dose of levothyroxine may need to be adjusted. Further, it is recommended to monitor the patient by checking the hormone levels in the serum.
Biotin may interfere with thyroid immunoassays that are based on a biotin/streptavidin interaction, leading to either falsely decreased or falsely increased test results. The risk of interference increases with higher doses of biotin.
When interpreting results of laboratory tests, possible biotin interference has to be taken into consideration, especially if a lack of coherence with the clinical presentation is observed. For patients taking biotin-containing products, laboratory personnel should be informed when a thyroid function test is requested. Alternative tests not susceptible to biotin interference should be used, if available (see Interactions).
Effects on bone mineral density: In women, long-term levothyroxine sodium therapy has been associated with increased bone resorption, thereby decreasing bone mineral density, especially in post-menopausal women on greater than replacement doses or in women who are receiving suppressive doses of levothyroxine sodium. The increased bone resorption may be associated with increased serum levels and urinary excretion of calcium and phosphorus, elevations in bone alkaline phosphatase and suppressed serum parathyroid hormone levels. Therefore, it is recommended that patients receiving levothyroxine sodium be given the minimum dose necessary to achieve a desired clinical and biochemical response.
Effects on the ability to drive and use machines: No studies on the effects on the ability to drive and use machines have been performed. However, since levothyroxine is identical to the naturally occurring thyroid hormone, it is not expected that Euthyrox has any influence on the ability to drive and use machines, if used as recommended.