Subclinical hypothyroidism: When to treat

[helvella]

Two snippets from the full paper:

Currently, the best practical approach is to base treatment decisions on the magnitude of elevation of thyroid-stimulating hormone (TSH) and whether the patient has thyroid autoantibodies and associated comorbid conditions.

Seems unbelievable that they don't even mention testing for T4 or T3 at this point. Nor signs and symptoms which might NOT be due to comorbid conditions.

The next snippet, though, is something that we have been banging the drum about since this forum started.

TSH secretion is pulsatile and has a circadian rhythm: serum TSH levels are 50% higher at night and early in the morning than during the rest of the day. Thus, repeated measurements in the same patient can vary by as much as half of the reference range.

I guess the authors are aware that a vast proportion of the medical professions are not aware of this. Otherwise there would be little point in giving this the prominence it has.

Cleve Clin J Med. 2019 Feb;86(2):101-110. doi: 10.3949/ccjm.86a.17053.

Subclinical hypothyroidism: When to treat.

Azim S1,2,3, Nasr C4,5.

Author information

1 Starling Physicians Endocrinology.

2 Medical Staff, Hartford Hospital, Hartford, CT, USA.

3 Clinical Assistant Professor, Department of Medicine, University of Connecticut School of Medicine, Hartford, CT, USA.

4 Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic, Cleveland, OH, USA. [e-mail].

5 Clinical Assistant Professor, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA.

Abstract

Subclinical hypothyroidism is defined by an elevated serum thyroid-stimulating hormone (TSH) level along with a normal free thyroxine (T4) level. Whether it should be treated remains controversial. Currently, the best practical approach is to base treatment decisions on the degree of TSH elevation, thyroid autoimmunity, and associated comorbidities.

Copyright © 2019 Cleveland Clinic.

PMID: 30742580

DOI: 10.3949/ccjm.86a.17053

ncbi.nlm.nih.gov/pubmed/307...

Full test freely available here:

mdedge-files-live.s3.us-eas...

[Adam10]

Thanks helvella

Does this mean we should choose the time of day when having blood tests taken for TSH and FT4 etc?

Should we give blood in the morning, midday, or in the evening?

[helvella Administrator in reply to Adam10]

Time of day makes a significant difference to TSH in most of us. So, yes, if you want your TSH to show its highest value, get blood drawn as early in the day as possible.

Further, it is appropriate to get them done at as near the same time as we can manage, every time, for the sake of consistency.

ncbi.nlm.nih.gov/pubmed/228...

[Adam10 in reply to helvella]

Thanks helvella.

So if TSH is highest value at early in the day (i.e. 2 not 1) does that mean it is a more pessimistic reading i.e. the lower reading later in the day would indicate a better health level of TSH and thus indicate less need to increase T4 dosage?

I usually have my blood drawn early morning as it’s easier to fast overnight and I don’t take my Levo the previous night to avoid skewing the TSH test which would cause an inaccurately good (lower value TSH) reading.

Grateful for your thoughts.

[helvella Administrator in reply to Adam10]

Yes - exactly so.

[kissemiss]

Thank you for sharing this useful information.