"What is hypothyroidism?
Hypothyroidism is a condition characterized by abnormally low thyroid hormone production. There are many disorders that result in hypothyroidism. These disorders may directly or indirectly involve the thyroid"...
Patients should be informed of the following information to aid in the safe and effective use of UNITHROID (levothyroxine sodium) :
1. Notify your physician if you are allergic to any foods or medicines, are pregnant or intend to become pregnant, are breast-feeding or are taking any other medications, including prescription and over-the-counter preparations.
2. Notify your physician of any other medical conditions you may have, particularly heart disease, diabetes, clotting disorders, and adrenal or pituitary gland problems. Your dose of medications used to control these other conditions may need to be adjusted while you are taking UNITHROID (levothyroxine sodium) . If you have diabetes, monitor your blood and/or urinary glucose levels as directed by your physician and immediately report any changes to your physician. If you are taking anticoagulants (blood thinners), your clotting status should be checked frequently.
3. Use UNITHROID (levothyroxine sodium) only as prescribed by your physician. Do not discontinue or change the amount you take or how often you take it, unless directed to do so by your physician. 4. The levothyroxine in UNITHROID (levothyroxine sodium) is intended to replace a hormone that is normally produced by your thyroid gland. Generally, replacement therapy is to be taken for life, except in cases of transient hypothyroidism, which is usually associated with an inflammation of the thyroid gland (thyroiditis).
6. It may take several weeks before you notice an improvement in your symptoms.
7. Notify your physician if you experience any of the following symptoms: rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, fever, changes in menstrual periods, hives or skin rash, or any other unusual medical event.
8. Notify your physician if you become pregnant while taking UNITHROID (levothyroxine sodium) . It is likely that your dose of UNITHROID (levothyroxine sodium) will need to be increased while you are pregnant.
9. Notify your physician or dentist that you are taking UNITHROID (levothyroxine sodium) prior to any surgery. 10. Partial hair loss may occur rarely during the first few months of UNITHROID (levothyroxine sodium) therapy, but this is usually temporary.
11. UNITHROID (levothyroxine sodium) should not be used as a primary or adjunctive therapy in a weight control program.
12. Keep UNITHROID (levothyroxine sodium) out of the reach of children. Store UNITHROID (levothyroxine sodium) away from heat, moisture, and light.
Laboratory Tests General
The diagnosis of hypothyroidism is confirmed by measuring TSH levels using a sensitive assay (second generation assay sensitivity ≤0.1 mlU/L or third generation assay sensitivity ≤0.01 mlU/L) and measurement of free-T4.
The adequacy of therapy is determined by periodic assessment of appropriate laboratory tests and clinical evaluation. The choice of laboratory tests depends on various factors including the etiology of the underlying thyroid disease, the presence of concomitant medical conditions, including pregnancy, and the use of concomitant medications (see PRECAUTIONS, Drug Interactions and Drug-Laboratory Test Interactions). Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of UNITHROID (levothyroxine sodium) may be evidence of inadequate absorption, poor compliance, drug interactions, or decreased T4 potency of the drug product.
In adult patients with primary (thyroidal) hypothyroidism, serum TSH levels (using a sensitive assay) alone may be used to monitor therapy. The frequency of TSH monitoring during levothyroxine dose titration depends on the clinical situation but it is generally recommended at 6-8 week intervals until normalization. For patients who have recently initiated levothyroxine therapy and whose serum TSH has normalized or in patients who have had their dosage or brand of levothyroxine changed, the serum TSH concentration should be measured after 8-12 weeks. When the optimum replacement dose has been attained, clinical (physical examination) and biochemical monitoring may be performed every 6-12 months, depending on the clinical situation, and whenever there is a change in the patient's status. It is recommended that a physical examination and a serum TSH measurement be performed at least annually in patients receiving UNITHROID. (see PRECAUTIONS and DOSAGE AND ADMINISTRATION). Pediatrics
In patients with congenital hypothyroidism, the adequacy of replacement therapy should be assessed by measuring both serum TSH (using a sensitive assay) and total- or free-T4. During the first three years of life, the serum total- or free-T4 should be maintained at all times in the upper half of the normal range. While the aim of therapy is to also normalize the serum TSH level, this is not always possible in a small percentage of patients, particularly in the first few months of therapy. TSH may not normalize due to a resetting of the pituitary-thyroid feedback threshold as a result of in utero hypothyroidism. Failure of the serum T4 to increase into the upper half of the normal range within 2 weeks of initiation of UNITHROID (levothyroxine sodium) therapy and/or of the serum TSH to decrease below 20 mU/L within 4 weeks should alert the physician to the possibility that the child is not receiving adequate therapy. Careful inquiry should then be made regarding compliance, dose of medication administered, and method of administration prior to raising the dose of UNlTHROID.
The recommended frequency of monitoring of TSH and total or free T4 in children is as follows: at 2 and 4 weeks after the initiation of treatment; every 1-2 months during the first year of life; every 2-3 months between 1 and 3 years of age; and every 3 to 12 months thereafter until growth is completed. More frequent intervals of monitoring may be necessary if poor compliance is suspected or abnormal values are obtained. It is recommended that TSH and T4 levels, and a physical examination, if indicated, be performed 2 weeks after any change in UNITHROID (levothyroxine sodium) dosage. Routine clinical examination, including assessment of mental and physical growth and development, and bone maturation should be performed at regular intervals (see PRECAUTIONS, Pediatric Use and DOSAGE AND ADMINISTRATION).
Secondary (pituitary) and tertiary (hypothalamic) hypothyroidism
Adequacy of therapy should be assessed by measuring serum free-T4 levels, which should be maintained in the upper half of the normal range in these patients.
Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.
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