The lack of clinical congruence in diagnosis and research in relation to subclinical hypothyroidism

8 01 2014

To the Editor:

We have just read a publication by Bernardi et al. on the topic of subclinical hypothyroidism and recurrent early pregnancy loss (1). Going through the paper we found that the opposite situation was being described, that is, no impact of subclinical hypothyroidism on recurrent early pregnancy loss. This puzzling situation motivated us to dissect the concepts presented by the authors.

One central point of misconception on thyroid function can be tracked down to a 2007 publication cited by Bernardi which recommended a “desirable TSH level” of 2.5 mIU/ml for pregnant women. In that original publication the authors had admitted that this recommendation was done on the basis of a poor level of evidence. Although this recommendation does not fulfill the principles of evidence-based medicine, it has very unfortunately found its way into clinical practice. Choosing a low cut-off value for the upper range of TSH, as Bernardi et al. have done, will result in a misclassification of normal subjects by which the apparent subgroups, euthyroids and women with subclinical hypothyroidism, are not truly subgroups but belong to a same group of subjects having TSH values within the normal range. Therefore it is logical that one cannot expect to find any difference between these artificial subgroups in relation to recurrent early pregnancy loss.

To rely solely on a laboratory test result will lead to the situation described by Moons, Biesheuvel, and Grobbee in an article entitled: “Test research versus diagnostic research” (2). The opening lines of this article state: “The diagnostic workup starts with a patient presenting with symptoms or signs suggestive of a particular disease. The workup is commonly a consecutive process starting with medical history and physical examination and simple tests followed by more burdensome and costly diagnostic procedures. Generally, after each test all available results are converted (often implicitly) to a probability of disease, which in turn directs decisions for additional testing or initiation of appropriate treatment. Setting a diagnosis is a multitest or multivariable process of estimating and updating the diagnostic probability of disease presence given combinations of test results.”

Our approach to the diagnosis of thyroid disease has been to implement a clinical examination together with the laboratory tests (3). We have recently extended the clinical approach to the use of 3D-power Doppler sonography, which allows us to investigate the influence of magnesium and selenium on thyroid function (4). By this, we put diagnostic research above the plain test research. In doing this we find agreement with the opinion of Brian Hurwitz on the interaction between clinical practice guidelines and legal and political considerations (5). In his summary he states: “… minimum acceptable standards of clinical care derive from responsible customary practice, not from guidelines.”

We are constantly confronted with the incorrect use of reference values for TSH. Gynecologists find that their patients have thyroidal illness even when TSH lies in the normal range (0.3 to 3.5 mIU/ml). A thorough examination according to our protocol discards thyroid disease in the great majority of cases.

Helga Moncayo, M.D. and Roy Moncayo, M.D.
WOMED, Innsbruck, Austria

References

1. Bernardi LA, Cohen RN, Stephenson MD. Impact of subclinical hypothyroidism in women with recurrent early pregnancy loss. Fertil Steril 2013;100:1326-31.

2. Moons KG, Biesheuvel CJ, Grobbee DE. Test research versus diagnostic research. Clin Chem 2004;50:473-6.

3. Moncayo H, Dapunt O, Moncayo R. Diagnostic accuracy of basal TSH determinations based on the intravenous TRH stimulation test: An evaluation of 2570 tests and comparison with the literature. BMC Endocrine Disorders 2007;7:5.

4. Moncayo R, Moncayo H. Advanced 3D sonography of the thyroid: focus on vascularity. In Sonography. Edited by Thoirs K. Intech; 2012:273-92.

5. Hurwitz B. Legal and political considerations of clinical practice guidelines. BMJ 1999;318:661-4.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2014.01.010

Advertisements

Actions

Information

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




%d bloggers like this: