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Even with appropriate treatment, your condition will prevent you from becoming pregnant
0%
0/41
Improved PKU treatment will decrease the risks of spontaneous abortion and intrauterine fetal death
41%
17/41
3 months prior to conception, begin a restricted diet to lower phenylalanine levels to below 6 mg/dL
37%
15/41
Begin a phenylalanine-restricted diet in your first trimester to reduce the risk of fetal morbidity
17%
7/41
Your current phenylalanine levels do not pose a risk to any future pregnancy
2%
1/41
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For this patient with phenylketonuria (PKU) who wishes to become pregnant, it is best to lower her phenylalanine levels to below 6 mg/dL before becoming pregnant, and maintain low levels throughout the pregnancy, in order to reduce the risk of neonatal sequelae. Phenylketonuria is caused by a deficiency in phenylalanine hydroxylase or tetrahydrobiopterin cofactor, leading to a toxic build-up of phenylalanine in the blood. Infants with PKU have blonde hair, blue eyes & fair skin (due to impaired melanin synthesis), eczema, a "mousy" body odor, and develop mental retardation within the first months of life if the disease is not recognized and managed. Screening for PKU at birth allows for early detection and institution of a phenylalanine-restricted diet to reduce and prevent the development of brain damage. Hellekson reviews the NIH consensus statement on phenylketonuria. Control of phenylalanine levels before and during pregnancy is essential. Exposure of a fetus to elevated levels of phenylalanine can lead to a host of complications including microcephaly, intellectual disability, congenital heart disease, and facial dysmorphism. The NIH consensus panel recommends lowering phenylalanine levels to less than 6 mg/dL 3 months prior to pregnancy and continuation of this control throughout pregnancy. Prick et al. discuss the pregnancy-related complications and neonatal outcomes that result from treatment versus nontreatment of maternal phenylketonuria and hyperphenylalaninemia in pregnancy. Treatment status did not affect the incidence of spontaneous abortion, intrauterine fetal death, or preterm delivery; however, appropriate treatment of PKU was associated with a decrease in neonatal microcephaly, congenital heart disease, intellectual disability, and facial dysmorphism. Illustration A summarizes the risks to the fetus in a pregnancy complicated by maternal PKU. Illustration B summarizes the biochemical pathophysiology of phenylketonuria; note how the lack of phenylalanine hydroxylase leads to the accumulation of phenylalanine. Incorrect Answers: Answer 1: Women with or without treatment for PKU are able to conceive and bear children; although treatment of the disease to lower phenylalanine levels improves neonatal morbidity. Answer 2: Studies have shown that the rate of occurrence of pregnancy complications, including spontaneous abortion, intrauterine fetal death, and preterm delivery, is not significantly different between treated and untreated pregnancies in PKU patients. Answer 4: Phenylalanine levels in the 2-6 mg/dL range should be reached and maintained 3 months prior to pregnancy through delivery; good control of phenylalanine levels is perhaps most critical in the first trimester when the bulk of organogenesis occurs. Answer 5: A phenylalanine level > 20 mg/dL is diagnostic of PKU and poses a significant risk of development of fetal complications, such as microcephaly, intellectual disability, congenital heart disease, or facial dysmorphism.
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