Diagnostic
PREGNANCY RECOMMENDATION: Compatible (Intravenous Use)
BREASTFEEDING RECOMMENDATION: Limited Human Data—Probably Compatible
PREGNANCY SUMMARY
The various preparations of iohexol contain a high concentration of organically bound iodine. In the two reports below, the authors concluded that IV iodinated contrast material did not harm the thyroid function of newborns.
FETAL RISK SUMMARY
Iohexol, a nonionic radiopaque agent, contains a high concentration of organically bound iodine (140–350 mg iodine/mL). Iohexol was not detected in the fetuses or amniotic fluid of mid-term rabbits (1).
A study published in 2010 described the thyroxine (T4) and/or thyroid stimulating hormone (TSH) concentrations in newborns whose mothers received IV iohexol during pregnancy (2). The data for the study came from 344 maternal and 343 newborn records. The mothers had undergone multidetector pulmonary computed tomographic angiography because of suspected pulmonary embolism between 2004 and 2008. The mean gestational age of the test was 27.8 weeks and the mean dose of total iodine administered was 45,000 mg/L. All newborns had a normal T4 concentration at birth. One newborn had a transiently abnormal TSH, which normalized at day 6 of life (2).
A 2012 study evaluated the thyroid function of 64 neonates who been exposed in utero when 61 mothers had received IV iodinated contrast material (not further identified) for computed tomographic scans (3). One neonate had a low T4 concentration but a normal TSH level. That infant was born at 25 weeks’ and developed respiratory distress syndrome and sepsis (3).
BREASTFEEDING SUMMARY
Iohexol is excreted into breast milk (3). Four lactating women received the IV contrast media (1 mL/kg) (1 mL contained 350 mg iodine) in the postpartum period (1 week to 14 months) (4). Breastfeeding was stopped for 48 hours. The amount excreted over a 24-hour period was 0.5% of the maternal weight-adjusted dose. This amount did not appear to be clinically significant (4). The American Academy of Pediatrics classifies iohexol as compatible with breastfeeding (5).
References
1.Bourrinet P, Dencausse A, Havard P, Violas X, Bonnemain B. Transplacental passage and milk excretion of iobitridol. Invest Radiol 1995;30:156–8.
2.Bourjeily G, Chalhoub M, Phornphutkul C, Alleyne TC, Woodfield CA, Chen KK. Neonatal thyroid function: effect of a single exposure to iodinated contrast medium in utero. Radiology 2010;256:744–50.
3.Kochi MH, Kaloudis EV, Ahmed W, Moore WH. Effect of in utero exposure of iodinated intravenous contrast on neonatal thyroid function. J Comput Assist Tomogr 2012;36:165–9.
4.Nielsen ST, Matheson I, Rasmussen JN, Skinnemoen K, Andrew E, Hafsahl G. Excretion of iohexol and metrizoate in human breast milk. Acta Radiol 1987;28:523–6.
5.Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 2001;108:776–89.