Borstvoeding en schildklierremmers
Geplaatst: 27 mar 2018, 12:30
Omdat vragen over borstvoeding en het gebruik van strumazol of PTU geregeld gesteld worden op schildklierfora.
2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum
Question 92: Are ATDs (PTU, MMI) transferred into breast milk, and what are the clinical consequences to the breastfed infant?
Both PTU and MMI can be detected in the breast milk of treated hyperthyroid women. This finding raised initial concern that consumption of these medications could prove detrimental to the health of the breastfeeding infant. However, studies first performed using PTU confirmed that only a very small amount of the drug is transferred from maternal serum into breast milk. In a study of nine women given 200 mg PTU orally, milk PTU concentration was measured for 4 hours thereafter and only 0.007%–0.077% of the ingested dose was detected. The authors calculated that a lactating mother consuming PTU 200 mg three times daily would transmit only 149 μg (0.149 mg) of PTU daily to her infant (538). This is well below a therapeutic dose and deemed to pose no risk to the breastfeeding infant. Separate studies confirm normal thyroid function in breastfed infants of mothers consuming PTU (539,540). In these studies, two infants were found to have an elevated TSH within 1 week of birth, however, these values normalized thereafter despite continued breastfeeding. This suggests the cause of neonatal hypothyroidism in these infants was transplacental passage of PTU before birth, as opposed to any adverse effect of PTU transferred via breast milk. The remaining children who consumed breast milk expressed from mothers taking PTU had normal thyroid function.
Studies of MMI or CM, confirm a 4- to 7-fold higher proportion of the medication transferred into maternal milk in comparison to PTU. Approximately 0.1%–0.2% of an orally administered MMI/CM dose is excreted into breast milk (541,542). Johansen and colleagues (541) calculated that a single 40 mg dose of MMI could result in delivery of 70 μg (0.07 mg) to the breastfeeding infant. Several studies have separately investigated the effect of maternally ingested MMI or CM upon the thyroid status of the breastfeeding infant (543–545). Virtually all have documented normal neonatal thyroid function. Furthermore, several women overtreated with MMI/CM were found to have elevated TSH concentrations (TSH 19–102 mU/L). Even in these situations, normal neonatal thyroid function was nonetheless confirmed in breastfeeding infants.
The largest study investigating the effects of maternal MMI consumption during lactation was performed by Azizi and colleagues (545). Importantly, this study assessed both neonatal thyroid function in the breastfeeding offspring, but also intellectual development and physical growth in a subset of infants. Verbal and performance IQ scores were measured in 14 children who breastfed from MMI-treated mothers, with comparison to 17 control children. Testing was performed between 48 and 74 months of age. No difference was detected in the IQ or physical development of the breastfeeding children compared to the control children (543).
Together, these data have led experts to confirm the safety of low to moderate doses of both PTU and MMI/CM in breastfeeding infants. However, given the relatively small size of the studied population, maximal daily doses of 20 mg MMI or 450 mg PTU are advised (352).
Question 93: What is the approach to the medical treatment of maternal hyperthyroidism in lactating women?
■ RECOMMENDATION 78
Excepting treatment decisions specifically made on the grounds of improving lactation (discussed above), the decision to treat hyperthyroidism in lactating women should be guided by the same principles applied to nonlactating women.
Strong recommendation, low-quality evidence.
Question 94: When medical treatment of maternal hyperthyroidism is indicated, what medications should be administered?
■ RECOMMENDATION 79
When antithyroid medication is indicated for women who are lactating, both MMI (up to maximal dose of 20 mg/d) and PTU (up to maximal dose of 450 mg/d) can be administered. Given a small, but detectable amount of both PTU and MMI transferred into breast milk, the lowest effective does of MMI/CM or PTU should always be administered.
Strong recommendation, moderate-quality evidence.
Question 95: How should breastfeeding children of mothers who are treated with antithyroid medications be monitored?
■ RECOMMENDATION 80
Breastfed children of women who are treated with ATDs should be monitored for appropriate growth and development during routine pediatric health and wellness evaluations. Routine assessment of serum thyroid function in the child is not recommended.
Weak recommendation, moderate-quality evidence.
2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum
Question 92: Are ATDs (PTU, MMI) transferred into breast milk, and what are the clinical consequences to the breastfed infant?
Both PTU and MMI can be detected in the breast milk of treated hyperthyroid women. This finding raised initial concern that consumption of these medications could prove detrimental to the health of the breastfeeding infant. However, studies first performed using PTU confirmed that only a very small amount of the drug is transferred from maternal serum into breast milk. In a study of nine women given 200 mg PTU orally, milk PTU concentration was measured for 4 hours thereafter and only 0.007%–0.077% of the ingested dose was detected. The authors calculated that a lactating mother consuming PTU 200 mg three times daily would transmit only 149 μg (0.149 mg) of PTU daily to her infant (538). This is well below a therapeutic dose and deemed to pose no risk to the breastfeeding infant. Separate studies confirm normal thyroid function in breastfed infants of mothers consuming PTU (539,540). In these studies, two infants were found to have an elevated TSH within 1 week of birth, however, these values normalized thereafter despite continued breastfeeding. This suggests the cause of neonatal hypothyroidism in these infants was transplacental passage of PTU before birth, as opposed to any adverse effect of PTU transferred via breast milk. The remaining children who consumed breast milk expressed from mothers taking PTU had normal thyroid function.
Studies of MMI or CM, confirm a 4- to 7-fold higher proportion of the medication transferred into maternal milk in comparison to PTU. Approximately 0.1%–0.2% of an orally administered MMI/CM dose is excreted into breast milk (541,542). Johansen and colleagues (541) calculated that a single 40 mg dose of MMI could result in delivery of 70 μg (0.07 mg) to the breastfeeding infant. Several studies have separately investigated the effect of maternally ingested MMI or CM upon the thyroid status of the breastfeeding infant (543–545). Virtually all have documented normal neonatal thyroid function. Furthermore, several women overtreated with MMI/CM were found to have elevated TSH concentrations (TSH 19–102 mU/L). Even in these situations, normal neonatal thyroid function was nonetheless confirmed in breastfeeding infants.
The largest study investigating the effects of maternal MMI consumption during lactation was performed by Azizi and colleagues (545). Importantly, this study assessed both neonatal thyroid function in the breastfeeding offspring, but also intellectual development and physical growth in a subset of infants. Verbal and performance IQ scores were measured in 14 children who breastfed from MMI-treated mothers, with comparison to 17 control children. Testing was performed between 48 and 74 months of age. No difference was detected in the IQ or physical development of the breastfeeding children compared to the control children (543).
Together, these data have led experts to confirm the safety of low to moderate doses of both PTU and MMI/CM in breastfeeding infants. However, given the relatively small size of the studied population, maximal daily doses of 20 mg MMI or 450 mg PTU are advised (352).
Question 93: What is the approach to the medical treatment of maternal hyperthyroidism in lactating women?
■ RECOMMENDATION 78
Excepting treatment decisions specifically made on the grounds of improving lactation (discussed above), the decision to treat hyperthyroidism in lactating women should be guided by the same principles applied to nonlactating women.
Strong recommendation, low-quality evidence.
Question 94: When medical treatment of maternal hyperthyroidism is indicated, what medications should be administered?
■ RECOMMENDATION 79
When antithyroid medication is indicated for women who are lactating, both MMI (up to maximal dose of 20 mg/d) and PTU (up to maximal dose of 450 mg/d) can be administered. Given a small, but detectable amount of both PTU and MMI transferred into breast milk, the lowest effective does of MMI/CM or PTU should always be administered.
Strong recommendation, moderate-quality evidence.
Question 95: How should breastfeeding children of mothers who are treated with antithyroid medications be monitored?
■ RECOMMENDATION 80
Breastfed children of women who are treated with ATDs should be monitored for appropriate growth and development during routine pediatric health and wellness evaluations. Routine assessment of serum thyroid function in the child is not recommended.
Weak recommendation, moderate-quality evidence.