#249 Helping physicians fatigued by TSH Screening and Subclinical Hypothyroidism
CLINICAL QUESTION
Is there evidence for screening for thyroid function or treating subclinical hypothyroidism?
BOTTOM LINE
There is no randomized controlled trial (RCT) of screening for thyroid function [ordering thyroid stimulating hormone (TSH) in non-pregnant healthy people]. Despite approximately 20 RCTs, there are no patient-oriented benefits (like preventing cardiovascular disease or reduced fatigue or weight) in treating subclinical hypothyroidism. Guidelines recommend against both.
Reading Tools for Practice Article can earn you MainPro+ Credits
Join NowAlready a CFPCLearn Member? Log in
EVIDENCE
Screening for thyroid function: No RCTs or controlled observational studies assess screening for thyroid function or the use of TSH test for screening.1,2
Treating subclinical hypothyroidism (TSH 4-10 but T3/T4 normal):
- Clinical endpoints: Four systematic reviews (with 18-21 RCTs)1-4 from the last 5 years report on 18-21 RCTs.1-4 Treatment of subclinical hypothyroidism (levothyroxine typically) versus placebo had no effect on:
- Mortality or new cardiovascular disease.2-4
- Quality of life, depressive symptoms, fatigue, or thyroid-related symptoms scores.1-4
- Cognitive function.1-4
- BMI/Weight.1-4
- Newest RCT, 251 elderly patients (mean age 85), no benefit on any outcome (~1.5-year follow-up).5
- Surrogate markers:
- Blood Pressure (BP): Three systematic reviews found no difference,1,2,4 while another found systolic BP reduced 2.5 mmHg (not diastolic).6
- Lipids: Of four systematic reviews, two found no effect and two found treatment reduced total cholesterol or LDL 0.1-0.6 mmol/L (no change in HDL or triglycerides).7,8
- There is no evidence these small, inconsistent changes matter clinically.
- Subclinical Hypothyroidism generally defined as TSH ~4-10mIU/L, with normal T3/T4 and no clear symptoms of hypothyroidism.
- TSH may vary up to 50% between tests9 and daily fluctuations10 in individuals can be 26%.
- Prevalence of subclinical hypothyroidism (in the developed world) is 4-10%, with 2-6% of these developing overt hypothyroidism. Subclinical hyperthyroidism prevalence is ~2% with 1-2% of these developing overt hyperthyroidism.2,11
- 40% subclinical hypothyroidism revert to normal over ~2.5 years.12
- Symptoms are often poor predictors. Example: one study found ~18% of euthyroid, ~22% subclinical hypothyroid, ~26% overt hypothyroid patients reported ≥4 symptoms of hypothyroidism.13
- Canadian Task Force on Preventive Health Care recommends against screening for thyroid function in asymptomatic non-pregnant patients or treating subclinical hypothyroidism.14
Latest Tools for Practice
#378 Tony Romo-sozumab: Winning touchdown in osteoporosis or interception for the loss?
What is the efficacy and safety of romosozumab in postmenopausal women with osteoporosis?
#377 How to slow the flow IV: Combined oral contraceptives
In premenopausal heavy menstrual bleeding due to benign etiology, do combined oral contraceptives (COC) improve patient outcomes?
#376 Testosterone supplementation for cis-gender men: Let’s (andro-)pause for a moment (Update)
What are the benefits and harms of testosterone supplementation in healthy cis-gender men or those with age-related low testosterone?
Interesting evidence kidney now convince our patients of this
I’m thinking that a presenting symptom of ‘fatigue’ meets criteria for clinical hypothyroidism?
Confirms my present management