Newborn metabolic screen -- once is not enough?

[msmiranda]

I have tried to do online research about this and I have ended up really confused, so I am hoping there is someone here who has the skinny and can help me out.  So, I have read in many reliable sources that the PKU part of the newborn metabolic screen is not that accurate until a baby has been drinking breast milk (not colostrum) for at least 24 hours.  But I have also read that it is better to catch the other disorders the test screens for as early as possible.  Does that mean there is no way to avoid having my baby put through that torture twice?  I initially decided to decline the test in the hospital, as it's unlikely we'll be there when my milk first comes in, much less 24 hours after that, and have it done at the first ped visit, which would probably be about 2 days after leaving the hospital.  Is that too late for detecting the other disorders?  FWIW, with my first two the test was done "too early" for it to be accurate w/r/t PKU, but we were NOT asked to do it a second time.  Still, it doesn't seem to make sense to do it this way (24 hrs after birth with my first, 48 for my second) for breastfed babies.  Yet I rarely hear anyone question it.  Is this because PKU is so rare that the chance of a breastfed baby slipping through the cracks is infinitesmally small? 

Any thoughts?

[konayossie]

I believe the PKU test is supposed to be done 36 hours after birth. Many hospitals will do the test before a baby checks out, even if it's not been 36 hours since birth b/c they are "mandated" to do it on every newborn, and then if you actually want accurate results, you'll need to have it done again. My plan if we were to check out prior to 36 hours is to decline the test in the hospital and take the baby to get it done at the ped later. No way I'm letting them milk my baby's little heel more times than absolutely necessary. And it's definitely not a test you want inaccurate results on. I have never read that the disorders they are testing for will be deadly to a baby prior to 36 hours, so there's no danger till waiting for the test to be accurate.

[Tumble Bumbles]

There is no real window on when you can get the test, but obviously getting it as soon as you feel comfortable is best because if your child did have one of the disorders on the metabolic screening, you'd want to know as soon as possible!

I've read it's best to get the test after feeding is established -- PKU in particular is a disorder where the body cannot handle protein, so doing it when a baby has only had colostrum seems inaccurate. The metabolic test screens for several conditions, though -- none to my knowledge are 'deadly' in the first few days.

We are planning a UC and will be going to our trusted family doc within 3-4 days. He said he can either do the heel prick there or write us a script for a local hospital lab where they can do it there if we choose.

[Ola_]

I believe our midwife said the optimal time for the test is between 24 and 72 hrs?  We had a homebirth though so they came to visit almost every day for a while, which gives you more options for when to test than if your choices are while you're still at the hospital or in the ped's office.

[Jaimee]

It was my understanding that these tests are not accurate until baby has digested some food and the only reason they are done right away is because most births occur in hospitals and many check out within 24-48 hours.  Baby does not need to be tested twice if you wait long enough to make the test reliable.

We decided to only have the test done once, five days after birth.  Our homebirth midwife as at our house for a pp visit and did the blood draw for us.  Much nicer than doing it twice.  PKU does not run in our family so we were not concerned about that.

[msmiranda]

Yeah, I pretty much can't get a straight answer.  I think I will have to talk to the ped about it and see what he says (if he even knows).  I also printed out a very long paper written by the AAP that explains each disorder screened for and gives more details about what conditions need to be in place for the test to be accurate.  I haven't read it yet because it is SO LONG.  I would just like the test to be done once at whatever is the best and most accurate time for all the things it screens for.  I don't think that's so much to ask. :)

[msmiranda]

Originally Posted by Jaimee 

It was my understanding that these tests are not accurate until baby has digested some food and the only reason they are done right away is because most births occur in hospitals and many check out within 24-48 hours.  Baby does not need to be tested twice if you wait long enough to make the test reliable.

We decided to only have the test done once, five days after birth.  Our homebirth midwife as at our house for a pp visit and did the blood draw for us.  Much nicer than doing it twice.  PKU does not run in our family so we were not concerned about that.

Yeah, that was sort of the idea I had too.  I guess I don't really see why it is the hospital's responsibility to perform this test ... I guess it is because they think that a lot of people don't take their baby to the ped?  Otherwise I would think that it is really the ped's job to make sure the test is done since they have "jurisdiction" over the baby at the time it is most likely to be accurate. 

[nia82]

We had DD tested at day 10. CO does it twice, at birth and around 10-12 days but we declined the first test and went straight for the second only.