8 USE IN SPECIFIC POPULATIONS
Experience with liothyronine use in pregnant women, including data from post-marketing studies, have not reported increased rates of major birth defects or miscarriages (see Data). There are risks to the mother and fetus associated with untreated hypothyroidism in pregnancy. Since TSH levels may increase during pregnancy, TSH should be monitored and CYTOMEL dosage adjusted during pregnancy (see Clinical Considerations). There are no animal studies conducted with liothyronine during pregnancy. CYTOMEL should not be discontinued during pregnancy and hypothyroidism diagnosed during pregnancy should be promptly treated.
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
Disease-associated maternal and/or embryo/fetal risk
Maternal hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, gestational hypertension, pre-eclampsia, stillbirth, and premature delivery. Untreated maternal hypothyroidism may have an adverse effect on fetal neurocognitive development.
Dose adjustments during pregnancy and the postpartum period
Pregnancy may increase CYTOMEL requirements. Serum TSH levels should be monitored and the CYTOMEL dosage adjusted during pregnancy. Since postpartum TSH levels are similar to preconception values, the CYTOMEL dosage should return to the pre-pregnancy dose immediately after delivery [see Dosage and Administration (2.3)].
Limited published studies report that liothyronine is present in human milk. However, there is insufficient information to determine the effects of liothyronine on the breastfed infant and no available information on the effects of liothyronine on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for CYTOMEL and any potential adverse effects on the breastfed infant from CYTOMEL or from the underlying maternal condition.
8.4 Pediatric Use
The initial dose of CYTOMEL varies with age and body weight. Dosing adjustments are based on an assessment of the individual patient's clinical and laboratory parameters [see Dosage and Administration (2.3, 2.4)].
In pediatric patients in whom a diagnosis of permanent hypothyroidism has not been established, discontinue thyroid hormone for a trial period, but only after the child is at least 3 years of age. Obtain serum TSH, T4, and T3 levels at the end of the trial period, and use laboratory test results and clinical assessments to guide diagnosis and treatment, if warranted [see Dosage and Administration (2.6)].
Congenital Hypothyroidism [see Dosage and Administration (2.2, 2.6)]
Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on intellectual development as well as on overall physical growth and maturation. Therefore, initiate thyroid hormone immediately upon diagnosis. Thyroid hormone is generally continued for life in these patients.
Closely monitor infants during the first 2 weeks of thyroid hormone therapy for cardiac overload, arrhythmias, and aspiration from avid suckling.
Closely monitor patients to avoid undertreatment or overtreatment. Undertreatment may have deleterious effects on intellectual development and linear growth. Overtreatment is associated with craniosynostosis in infants, may adversely affect the tempo of brain maturation, and may accelerate the bone age and result in premature epiphyseal closure and compromised adult stature [see Dosage and Administration (2.6) and Adverse Reactions (6)].
Acquired Hypothyroidism in Pediatric Patients
Closely monitor patients to avoid undertreatment and overtreatment. Undertreatment may result in poor school performance due to impaired concentration and slowed mentation and in reduced adult height. Overtreatment may accelerate the bone age and result in premature epiphyseal closure and compromised adult stature.
Treated children may manifest a period of catch-up growth, which may be adequate in some cases to normalize adult height. In children with severe or prolonged hypothyroidism, catch-up growth may not be adequate to normalize adult height [see Adverse Reactions (6)].
8.5 Geriatric Use
Because of the increased prevalence of cardiovascular disease among the elderly, initiate CYTOMEL at less than the full replacement dose [see Dosage and Administration (2.3) and Warnings and Precautions (5.1)]. Atrial arrhythmias can occur in elderly patients. Atrial fibrillation is the most common of the arrhythmias observed with thyroid hormone overtreatment in the elderly.