Seven studies met the inclusion criteria (n=168 participants, range seven to 63): two of prospective parallel design and five paired studies. Risk of bias in the included trials was reported as low. The authors stated that the trials were free of selective reporting and no other bias was detected; however, only two studies reported any blinding and it was unclear who was blinded in those trials.
Compared to thyroid stimulating hormone suppression, thyroid stimulating hormone stimulation resulted in significantly greater numbers of patients with PET true positive lesions (OR 2.45, 95% CI 1.23 to 4.90, I2=0%; seven studies), PET-detected lesions (OR 4.92, 95% CI 2.70 to 8.95, I2=0%; four studies) and enhanced tumour-to-background ratio mean (WMD 0.86, 95% CI 0.08 to 1.64). Clinical management was altered in 12 out of 130 (9%) patients with thyroid stimulating hormone stimulation (OR 2.40, 95% CI 1.11 to 5.22; five paired studies).
No significant difference between thyroid stimulating hormone stimulation and suppression was found in the primary tumour standardised uptake value (SUVmax) of the detected lesions (four trials). None of the studies investigated survival, all-cause mortality, health-related quality of life, adverse effects, morbidity or costs.