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Tuesday, November 01, 2005

Feebee - CD4

Thanks for all your support and advice girls, has cheered me up and helped me move on. Also, Halloween was a huge success and I didn't even think about TTC all evening! It means I can look forward to Christmas without worrying that AF will arrive and spoil it.

I have spoken to my GP and a fertility care practitioner and it seems I do have a problem (my m/c could also be related to this). GP will do blood tests to check my progesterone and oestrogen levels a week after O, and will refer me to a specialist. If the bloods show a problem, it should be fairly easy to fix. Could be a few months before we get to see anyone, but we will keep trying in the meantime!

I'm trying to get my head around the fact that we could be in for the long haul, but am also pleased that there is something we can do about it. It's the powerlessness of TTC that gets me down the most - this way we can take back some control, even if it takes longer than expected.

3 Comments:

At 8:04 PM, Anonymous Lisau said...

Hi,
I am glad you are getting help figuring out your cycle/hormone levels & it's impact on your efforts to successfully conceive..you are right knowledge IS power. We also had a great Halloween so much so that we made a deal with the kids..they traded back candy & we will get them books in return (Not all of it but they had scads!)The costumes turned out great & Lily(6)announced to nearly everyone that "my mom made my costume herself"
(bless her heart.)

The HPT article is available at
www.medscape.com/viewarticle/469266

Heres to a successful pregnancy for us both one day reasonably soon!
Lisau

 
At 8:10 PM, Anonymous lisau said...

I couldn't get the link to work so just copied it, Here it is!
Feb. 13, 2004 — Most home pregnancy tests (HPTs) are not sensitive enough to detect pregnancy at the time of a missed menses, according to the results of a study published in the January issue of the American Journal of Obstetrics and Gynecology. The investigators caution that clinicians should understand the test limitations.

"Since their introduction in 1975, the number of commercially available HPTs has increased from four to more than 20 brands," write Laurence A. Cole, PhD, from the University of New Mexico in Albuquerque, and colleagues. "The objective of this investigation was to determine whether there is validity in the claim advertised by all HPT brands of >99% accuracy and use of the test at the first day of the missed period."

The investigators determined urine levels of human chorionic gonadotropin (hCG) around the time of the missed menses and calculated 5th and 95th centiles. Each of 18 different brands of HPTs was blindly tested six times with five concentrations of hCG, 0 to 100 mIU/mL. Sensitivity was defined as the concentration at which six of six brands of HPT yielded positive results at the suggested reading time or at a later time.

To detect 95% of pregnancies at the time of missing menses, the authors estimated that a sensitivity of 12.5 mIU/mL was needed. However, only one of the 18 HPTs tested had this sensitivity, and two gave false-positive or invalid readings if faintly discernible results were considered. Only 44% of the brands yielded clear positive results at 100 mIU/mL hCG, but all brands were positive at 100 mIU/mL if faintly discernible results and extended reading times were included. At the time of missed menses, a test with 100 mIU/mL sensitivity would detect approximately 16% of pregnancies.

The investigators question the greater than 99% accuracy claims made by the manufacturers, and they suggest that these guidelines be reexamined by the manufacturers. In their opinion, U.S. Food and Drug Administration 510(k) regulations should require measurements of clinical sensitivity for detecting pregnancy on the day of the missed menses and at other specific time points, as support for an accuracy claim.

"By doing so, a clearer understanding of diagnostic accuracy can be reported on each brand's package insert rather than the printing boldly 'over 99% accuracy' on the outside of the package," the authors write. "All these issues need to be considered to avoid delays in detection of pregnancy, not only for early commencement of prenatal care, but to allow for appropriate changes in medication and behavior consistent with healthy pregnancy (avoidance of alcohol, tobacco, and inappropriate medicines), or to seek earliest pregnancy termination if desired."

Am J Obstet Gynecol. 2004;190:100-105
Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:

* Describe factors that may lead to false-positive HPTs.
* Evaluate the sensitivity and specificity of HPTs in early pregnancy.

Clinical Context

Thanks to their ease of use and convenience, HPTs are a popular means for women to test for pregnancy. However, according to the authors of the current study, multiple factors may be involved in the case of a false-negative test. These possible reasons include straightforward issues such as misreading of the tests or difficult-to-read results as well as miscalculation of the time elapsed since the last menstrual period, prolonged implantation leading to reduced hCG levels, or early pregnancy loss leading to a prolonged amount of time between menses.

Sensitivity in early pregnancy is another issue that challenges the validity of HPTs. In a study by Butler and colleagues that appeared in the December 2001 issue of Clinical Chemistry, only two home pregnancy tests detected hCG at very low levels. Moreover, 60% of the devices examined had better detection limits for hCG than hyperglycosylated hCG, which is a stronger indicator of early pregnancy for HPTs.

The authors of the current study follow up this research by examining the sensitivity and specificity of various HPTs in a controlled environment.
Study Highlights

* The authors first calculated hCG levels found in women in early pregnancy. To do so, they collected urine samples of women between 4 weeks and 0 days and 4 weeks and 3 days after their last menstrual period. These 25 women were all attending a fertility clinic and had singleton pregnancies confirmed by serum hCG tests.
* A wide range of hCG levels were measured (23 - 2,348 mIU/mL). The median level was 49 mIU/mL, and the 5th and 95th percentiles for hCG level were 12.4 and 241 mIU/mL, respectively. Therefore, the authors concluded that an HPT would need to detect hCG levels of 12.4, 21, 34, and 58 to accurately diagnose pregnancy at 0, 1, 2, and 3 days after a missed menses.
* According to the thresholds listed above, aliquots of urine were meticulously prepared with recombinant hCG specimens to achieve hCG concentrations of 0, 12.5, 25, 50, and 100 mIU/mL.
* 18 brands of HPTs were assessed. They were purchased at different retail chains at different times to minimize lot-to-lot variations. All of the HPTs used similar mechanisms to detect pregnancy and had both a control window and a window to demonstrate a positive result.
* Each HPT was tested with the 5 different concentrations of urine hCG. For validation, the HPTs were retested with the 50 mIU/mL concentration. Each test was read according to the HPT instructions as well as at 10 minutes to ensure no positive results returning late.
* Researchers were blinded to the urine aliquot being tested, but they could not be blinded to the particular type of HPT.
* Overall, sensitivity tests for the HPTs were disappointing. Only 44% were positive at the highest hCG concentration of 100 mIU/mL; sensitivity increased to only 83% when those tests with a faintly discernible positive line were included. All 18 tests were only positive when tested with urine hCG concentrations of 100 mIU/mL, with the results read at 10 minutes, and with questionably positive results included.
* Brands with a longer waiting time (5 minutes) for results were no more accurate than those with a short waiting time (1 minute).
* Although no brand consistently provided accurate results at the suggested reading time for urine hCG concentrations of 12.5 or 25 mIU/mL, the "First Response, Early Results" brand was the most reliable in giving faintly positive results at 12.5 mIU/mL. "Answer" brand had 4 clearly positive readings at 12.5 mIU/mL. These brands — plus "Clear Blue Easy, One Minute" and "Clear Plan Easy" — were the most effective at giving clearly positive or faintly discernable positive responses at 25 mIU/mL.
* 3 brands ("Confirm," "Equate," and "Sav-On Osco One-Step") failed to give positive results at the manufacturer suggested reading time with urine hCG concentrations of 100 mIU/mL.
* "Confirm" and "Clear Choice" pregnancy tests gave false-positive results at urine hCG concentrations of 0 mIU/mL. Both of these tests also failed to yield a visible control band in 10 of 30 tests and in 9 of 30 tests, respectively.

Pearls for Practice

* HPTs are popular but can lead to false results through several mechanisms.
* The sensitivity of HPTs does not match the 99% accuracy rate that these products claim. Specificity and function of some tests are also questionable.

The full article is only available if you pay to join very technical medical sites-ones that physicians would probably use- at least as far as I looked.
Lisau

 
At 3:58 PM, Blogger Feebee said...

Hi Lisa

Sounds like you had a great Halloween too. I am dying for a big family just so we can loads of fun at Halloween, Easter, Christmas and birthdays! Thanks for the link. After last month's HPT disaster I am NOT going to torture myself with testing again, esp as we'll be taking things a bit easier this month.

 

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