From the Guidelines
Hypothyroidism is a condition where the thyroid gland doesn't produce enough thyroid hormones, and treatment typically involves daily oral levothyroxine (T4) replacement therapy, starting at 1.6 mcg/kg body weight for most adults, with lower doses (25-50 mcg) for elderly patients or those with heart disease, as recommended by the U.S. Preventive Services Task Force 1. The medication should be taken on an empty stomach, 30-60 minutes before breakfast, and separated from calcium, iron supplements, and certain medications by at least 4 hours. TSH levels should be checked 6-8 weeks after starting treatment to adjust dosing, with a target TSH of 0.5-2.5 mIU/L for most adults, according to the Annals of Internal Medicine 2. Common symptoms of hypothyroidism include:
- Fatigue
- Cold intolerance
- Weight gain
- Dry skin
- Constipation
- Depression Regular monitoring is essential as thyroid requirements may change over time due to aging, weight changes, pregnancy, or other medications. Patients should maintain consistent timing of medication intake and avoid abruptly stopping treatment, as this can lead to serious complications including myxedema coma in severe cases, as noted in the study published in the Annals of Internal Medicine 3. The U.S. Preventive Services Task Force found no direct evidence that treatment of thyroid dysfunction based on risk level alters final health outcomes, but recommends treatment for patients with a TSH level that is undetectable or less than 0.1 mIU/L, particularly those with overt Graves disease or nodular thyroid disease 4. It is also important to note that overdiagnosis and overtreatment are of concern, as they can lead to unnecessary treatment and psychological consequences, as well as increased risk for osteoporosis, fractures, abnormal cardiac output, or ventricular hypertrophy 5. Therefore, treatment should be individualized and based on the patient's specific needs and risk factors, with careful monitoring and adjustment of medication as needed, to minimize the risk of adverse effects and optimize treatment outcomes, as recommended by the U.S. Preventive Services Task Force 6.
From the FDA Drug Label
Pediatric Patients at Risk for Hyperactivity To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached Hypothyroidism in Pregnant Patients For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range 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 T4 to increase into the upper half of the normal range within 2 weeks of initiation of levothyroxine sodium therapy and/or of the serum TSH to decrease below 20 IU per litre within 4 weeks may indicate the patient is not receiving adequate therapy
The symptoms of hypothyroidism are not directly stated in the label, but the treatment options include:
- Levothyroxine sodium tablets to normalize the serum TSH level
- Dosage adjustment:
- Start at one-fourth the recommended full replacement dosage and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached
- Increase levothyroxine sodium dosage by 12.5 to 25 mcg per day in pregnant patients
- Monitor TSH every 4 weeks until a stable dose is reached and serum TSH is within normal trimester-specific range
- Monitoring:
- Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation
- Monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage
- Evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status 7
From the Research
Symptoms of Hypothyroidism
- Fatigue, bradycardia, constipation, and cold intolerance are common symptoms of hypothyroidism 8, 9
- Polysaccharide accumulation in certain tissues can lead to hoarseness, eyelid swelling, etc. 8
- Subclinical hypothyroidism is usually asymptomatic, but may progress to overt hypothyroidism over time 8, 9
Treatment Options for Hypothyroidism
- Levothyroxine (L-T4) is the recommended lifelong replacement therapy for hypothyroidism 10, 8, 11, 9, 12
- The treatment goal is to achieve a TSH level within the reference range (0.4-4.0 mU/l) 9
- L-T4 monotherapy is the standard of care, but combination therapy with levotriiodothyronine (L-T3) may be considered in some cases 10, 12
- Treatment should be individualized based on factors such as patient age, presence of pregnancy or comorbidities, and TSH level 8, 9
Initiation and Monitoring of Treatment
- Treatment is usually initiated at a low dose (e.g. 25-50 µg) and adjusted based on TSH levels 11
- Dose adjustment should only be considered after 6-12 weeks, given the long half-life of levothyroxine 8
- Certain drugs, such as iron and calcium, can reduce the gastrointestinal absorption of levothyroxine, while enzyme inducers can reduce its efficacy 8
- Regular monitoring of TSH levels is necessary to avoid overtreatment or undertreatment 8, 9