Hello medical types,
I’m trying to get a little peace of mind tonight after not too good news from my doctor.
In the absence of knowledge or a handy expert to ask, I thought I would field this question to the SDMB.
I got a quantitative HCG test on Friday - my level was 1340. Today (Monday), it’s in the 900s. The doctor says this means the pregnancy is probably in danger. 
The thing is, on Friday I think I was probably dehydrated. I had cried for hours the night before (long story) and didn’t drink any water that morning. It took the phlebotomists four tries to get a vein. Today, by contrast, I drank loads of water (figuring I - and they - would have an easier time getting blood out). Could this variable have altered the test result for serum HCG concentration, making it more concentrated when I’d had no water, and therefore an artificially high level?
I’m really hoping that was the case. I hope someone out there who knows about medical lab stuff can answer this one. And I hope the answer is, “Yes, if you’re slightly dehydrated your levels can appear higher and when you’ve imbibed serious amounts of water your levels can appear less concentrated than when you haven’t had any water.”
Any other answer, that is the actual truth, is acceptable of course. Thank you very much for your (potential) help.
You may well have been dehydrated with the higher reading, but you absolutely need to be tested again to get and idea of where your HCG levels are going. A line can really only be determined by a minimum of three points. There could be other analytical reasons for the difference, but I don’t think they would explain a change of that magnitude. I hope that your pregnancy is not in danger.
Vlad/Igor, MT(ASCP)
Thank you Vlad/Igor. I hope the little one is okay too - of course. I am getting a third test on Wednesday. One of the nurses I talked to commented, “I don’t always trust labs - it may have been a testing error.” I pray that it was.
BHCG levels should approximately double every two to three days during the first trimester of pregnancy. This test is less accurate early in the pregnancy (and a level of 1000 is roughly four weeks), as well as later when dilution is required to get the number (more manipulation equals greater chance of error).
If the BHCG level does not double your pregnancy could indeed be in danger. However, it is also quite possible that the quantitative part of the test is less accurate in early pregnancy. The best thing to do would be simply to repeat the test in another three or four days and that result would be a much more useful indicator as to what is going on. An ultrasound in another two weeks would also be an option.
ggurl, just stay calm.
The best thing you can do is to rest, look after yourself and wait. Sometimes there is an error in the test, sometimes pregnancies take a while to get established, sometimes things don’t work out.
None of it is under your control (so don’t blame yourself, whatever happens), but taking good care of yourself is sensible. Don’t panic until you know more.
I really hope things work out for you.