Selenium supplementation for patients with Graves’ hyperthyroidism (the GRASS trial): study protocol for a randomized controlled trial

Table 1 Trial schedule for assessments

		Follow up
Variable	Inclusion (baseline)	6 weeks	12 weeks	6 months	12 months	18 months	24 months	12 (± 1) months after ATD treatment withdrawal^†
Visit	x					x		x
ATD treatment						x	x	x
Thyroid function	x¹					x¹		x¹
TSH-Receptor Antibodies	x¹					x_s		x_s
Serum selenium	x					(x_s)		(x_s)
Creatinine/iodine ratio in spot urine	x
Storage samples (blood and urine)	x					x		x
ThyPRO	x_r	x_r	x_r	x_r	x_r	x_r	x_r	x_r
Tablet count		x_r	x_r	x_r	x_r	x_r	x_r	x_r
Consumption of additional selenium				x_r	x_r	x_r	x_r
Adverse events*		x_r	x_r	x_r	x_r	x_r	x_r	x_r
Serious adverse events								x
Referral to ablative therapy						x		x

All assessments must be made at the time points specified above. If the assessment is not possible at the specified time, the assessment shall still be conducted, and the time shall be noted in the electronic case report form (eCRF). Following this, deviations from the protocol can be assessed. ¹As part of usual clinical practice (f = free (non-protein bound)), that is, all measured analyses are collected continuously from medical systems; x_s, analysed on stored plasma/serum samples after trial completion; x_r, self-reported data by participant; ^†participants for whom ATD treatment withdrawal has not been attempted, or has been unsuccessful, will be followed up at 36 months after randomisation (± 1 month). ATD, anti-thyroid drugs; TSH, thyroid stimulating hormone; ThyPRO, thyroid patient-reported outcome.

ISSN: 1745-6215