How long does it take phenylalanine to exit the body? I understand that everyones body works slightly differently, but once consumed, approximately how long before your body gets rid of phenylalanine? Hours? Days? Weeks?
With untreated PKU Phe does not exit the body. But in a “normal” person I would assume that it would be however long it takes that particular person to metabolize protein. WIth treated PKU I guess it would be how ever long it thats that person to metabolize the small amount of PHE they are allowed. That is a good question for a dietician.
Phe is, in fact, excreted from the body in people with PKU. The newborn screening test is based on that, in that it is a urine test. PKUers excrete a higher amount of phe in urine than non-PKUers, which is how a first screening for PKU is done. Non-PKUers do not excrete as much phe because their bodies break down the phe correctly, so there is less available to be excreted. As to how long it takes the body to excrete phe, I don’t know the answer to that.
Arkham, nThe urine test is actually how they used to diagnose PKU. They now use the Newborn Screening which is a heel prick and a few drops of blood on filter paper. It tests for plenty more disorders in additon to PKU.
Ok, that doesn’t surprise me. However, the point is the same. If PKU can be diagnosed (or at least a positive urine test can suggest that PKU needs to be tested for), phe is excreted in urine in higher concentrations in PKUers. Actually, this is the statement in Wikipedia regarding what is actually tested in urine, though it is missing a citation, which means that the source of it is questionable: “When PAH is deficient, phenylalanine accumulates and is converted into phenylpyruvate (also known as phenylketone), which is detected in the urine.”
Arkham, I am not saying that Wikipedia does not say that, but anybody can add information to Wikipedia. I have even written about PKU on the site due to inaccuracies. High levels of protein in the urine indicate PKU needs to be tested for but it is not a conclusive source. PHE does not exit the body of a person with PKU in the noraml fashion. If in the urine it indicates an excessive of protein in the body, such as that of too much Vitamin C.
I have a similar question my son get his levels always after a bottle of phenyl-free and not breast milk and the nutritionist has told me how older children fast before getting levels done. I do not totally understand this and am not finding the info online. Would the level be much higher after a breastmilk feed and does anyone know how long the level stays at a level before changing? Is it like a constant up and down with his levels from feed to feed.?
Gracie, your levels depend on if you have been taking your medicine, sticking to the diet, and other factors (such as exercsing which helps keeps levels down). I have never heard of fasting before getting a level taken. I am 20 years old and have never done so. In fact, I usually take my medicine right before I go to the hospital to get blood taken. I don't know how high a level would go because of a breastmilk feeding since the change depends on the person's tolerance but if your child is regularly consuming breastmilk already and their levels have been fine then I do not see what the problem is.
When I was younger I went through a short phase where my phe levels used to come back high one week, and low the next. My dietitian did mention doing my blood test at the same time everytime ie always doing my blood tests right before I go to bed, or right when I wake up. She never mentioned fasting before a blood test, but she did suggest doing it a few hours after I ate.
We decided against doing this, because we did not think it would change much. My levels just straightened themselves out.
As far as breastfeeding goes it could be possible that his phe levels do get a bit higher after breastfeeding him rather than after feeding him his formula. When my sister Erica was a baby my mom breastfed her and she found that her levels came back lower after drinking her formula, and high after breastfeeding. My mom solved this by giving my sister formula and breastmilk at the same time. She used the Supplemental Nursing System (SNS http://www.medelasuction.com/ISBD/breastfeeding/products/nursing.php), but there are other ways you could do this. You could feed him half a bottle at every feeding and breastmilk, rather than alternating formula and breastmilk at every feeding.
Hope this helps!
Breanna 18 CPKU