The Hook Effect Is Real!!! — The Bump
1st Trimester

The Hook Effect Is Real!!!

I don't know why I did it, but this morning, in a moment of insanity, I decided to do an HPT. I am 8 weeks today (my tickers are out for some reason) and just woke up with the idea I should see what was going on. I think it's partly because of the long wait between appointments and wanting to be sure I'm still pregnant (I've had 2 M/Cs).

Anyway, I used FMU and waited, and waited. The test took forever to come up with a test line and even when it did, it was REALLY REALLY faint!! Like the kind of faint I had with my first pregnancy when I had HCG levels of 15!

I didn't totally freak out, but I was definitely confused and a bit concerned. The reason I was more confused than worried is because I know my HCG levels were really high (56,000) only 2 weeks ago and they wouldn't have bottomed out so quickly even if things had gone wrong. 

So I did a bit of research and discovered the Hook Effect.

Basically the theory is that once your HCG levels reach a certain point, the HPT will struggle to process them. It seemed a bit odd but I decided to follow the advice to test again with diluted pee for a different result.

So, and here's a bit of TMI, I haven't been flushing during the night with pee because I'm going at least 4 times and the constant flushing from the ensuite would keep DH awake. So I decided to dip the stick in the loo (I know!!!) and test from there. 

Well lo and behold, a SUPER strong result within seconds that totally out coloured the control line.

The Hook Effect in full force. It is a very real thing. 

Luckily with that little experiment I used up my last 2 HPTs and I am absolutely definitely stepping away from the sticks now. I am happy to see my strong bold line again and will now wait patiently for our next appt.

PgAL brain SUCKS and definitely makes you do some cray cray stuff.  

 

TTC Since March 2010 - 2 angel babies - BFP December 12 EDD 12 Aug 13 Lilypie Maternity tickers Image and video hosting by TinyPic
linnae939

Re: The Hook Effect Is Real!!!

  • Very interesting!  I'd never heard of that.  Thx for sharing :)

     

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  • Took me a bit to figure out what you were saying. It could be possible that your urine was just too diluted, but The Hook Effect is rare. If it happened to you that is crazy. 

    "A false negative pregnancy test means that the test tells the patient they are not pregnant when they really are. Why does this occur? There are four well known reasons pregnancy tests can give false negative results.

    1) The most common reason is testing too early after fertilization occurs. The pregnancy hormone, hCG, is not produced until implantation occurs and it takes several days for the hCG concentrations to get high enough in blood and then urine to give a positive signal. Most devices give positive results around the day of a woman's expected period, but this can vary widely.

    2) Another reason for false negative results is dilute urine. If a woman drinks a lot of fluids, the concentration of hCG in the urine will be more dilute. For this reason many doctors recommend that testing be performed on the first urine of the morning because this tends to be the most concentrated (because you probably have not drank anything all night long).

    3) A very rare cause of false negative results occurs when very, very, high concentrations of hCG are present. This is called the high-dose hook effect. The hCG assays works by forming a so-called "sandwich" with two different antibodies as the "bread" and the hCG molecule as the "meat." The hook effect occurs when the hCG concentration is so high that it saturates both antibodies and there are so many molecules that the antibodies don't actually form a sandwich. This is rare because women don't normally produce enough hCG to saturate both antibodies. The hook effect should be of concern in a hospital setting, but most women should not be concerned about a hook effect with their urine. A hook effect can be confirmed if testing shows a positive result after sample dilution.

    4) Finally, the other reason for false negatives was only recently described and is referred to as the "variant hook effect." This is much more common than the hook effect. As pregnancy progresses, there are actually different variant forms of hCG that begin to appear in the urine. After about 5 weeks of pregnancy (i.e. 3 weeks after the expected period) concentrations of hCG beta core fragment are higher than all other forms of hCG. This is perfectly normal. Unfortunately, the concentration of hCG beta core fragment can saturate one of the antibodies used in the assay in certain pregnancy kits, and the other antibody doesn't recognize the beta core fragment. As a result, no sandwich forms and the test is read as a negative. The farther in pregnancy a woman is, the more likely that this false negative will occur. Similar to the hook effect, the variant hook effect can be confirmed if testing shows a positive result after diluting the sample.
    Posted by Ann M. Gronowski, PhD 5/8/11"


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  • I think your testing method is faulty and oh so very wrong. Pee in a cup and test that way. Your pee is diluted even by not flushing all night.
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  • I think perhaps your interpretation is wrong, not my testing method. 

    I did pee in a cup the first time, with FMU. My pee was not diluted which is the point. It was fully undiluted and produced a faint line.

    One way to verify that the Hook Effect is in play is to then dilute the pee (which it was in the loo after not flushing all night) and retest. This gave me a VERY strong clear line, even before the control line came up.

    Im pretty clear on what is diluted pee, and what's not. 

    I also know I have high levels of HCG and have seen the baby with a strong heartbeat so I am not a first time tester trying to figure out if I am pregnant. 

    TTC Since March 2010 - 2 angel babies - BFP December 12 EDD 12 Aug 13 Lilypie Maternity tickers Image and video hosting by TinyPic
  • I agree PrimRoseMae, it is rare, but not at all unheard of. And it's definitely a bit crazy!!!

    As mentioned above, my pee on the first test was FMU so definitely no where near as diluted as what was in the loo with a bowl full of water.

    I wouldn't have believed it myself if I didn't see it with my own eyes and already know that I am definitely pregnant.  

    TTC Since March 2010 - 2 angel babies - BFP December 12 EDD 12 Aug 13 Lilypie Maternity tickers Image and video hosting by TinyPic
  • image Lilmrslay:

    I think perhaps your interpretation is wrong, not my testing method. 

    I did pee in a cup the first time, with FMU. My pee was not diluted which is the point. It was fully undiluted and produced a faint line.

    One way to verify that the Hook Effect is in play is to then dilute the pee (which it was in the loo after not flushing all night) and retest. This gave me a VERY strong clear line, even before the control line came up.

    Im pretty clear on what is diluted pee, and what's not. 

    I also know I have high levels of HCG and have seen the baby with a strong heartbeat so I am not a first time tester trying to figure out if I am pregnant. 

    it doesn't seem people understand what you are saying. I totally followed you!

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  • image MayDayGirl:
    image Lilmrslay:

    I think perhaps your interpretation is wrong, not my testing method. 

    I did pee in a cup the first time, with FMU. My pee was not diluted which is the point. It was fully undiluted and produced a faint line.

    One way to verify that the Hook Effect is in play is to then dilute the pee (which it was in the loo after not flushing all night) and retest. This gave me a VERY strong clear line, even before the control line came up.

    Im pretty clear on what is diluted pee, and what's not. 

    I also know I have high levels of HCG and have seen the baby with a strong heartbeat so I am not a first time tester trying to figure out if I am pregnant. 

    it doesn't seem people understand what you are saying. I totally followed you!

     This. I didn't even know about this phenomenon. So weird! And I'm glad I haven't tested in weeks or it probably would have freaked me out so bad! 

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  • I had to google "hook effect" and then re-read your story to figure out what you were telling us, lol. But now that I get it, that's very interesting! :) Congrats on your pregnancy and congrats on stepping away from the sticks lol. I haven't suffered a loss and I still know all to well the obsessive need to keep peeing on sticks!
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  • Thanks for sharing your experience!! I, too, have suffered 2 m/c and am finally pregnant again. I will be 8 weeks tomorrow and yesterday decided to take a test since my symptoms seem to be slacking up so soon, and the tests I took were a lot lighter than the tests I took weeks before!! So, needless to say, this worried me. I went to the doc today and talked about my concerns, and he drew more blood mainly just to put my mind at ease. Results will be in tomorrow, but I am more confident now that I am starting to experience the Hook Effect! Still, the results from the blood work will officially put my mind at ease. And if all is well, then goodbye HPTs!!! LOL!
    ~Crystal~
    TTC since 2011
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    #3 BFP: July 2013 - Still going strong!! Found out at 16 week ultrasound that we are having a BOY!!
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