Investigations

• thyroid function tests ^a  

Why?

• 5% of patients admitted as an acute medical emergency with atrial fibrillation have thyrotoxicosis, but only 0.5% of patients on acute medical wards ^b

A low TSH level alone is insufficient to diagnose hyperthyroidism

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability
suspected hyperthyroidism b (pre-test probability: 5%)	hyperthyroidism	TSH <0.1 mU/ml	7.7 (5.6 to 11)	29%
		TSH: 0.1 to 0.6 mU/ml	0.0 (0.0 to 1.6)	0%
		TSH > 0.6 to 6.7 mU/ml	0.0 (0.0 to 1.9)	0%