T3 Total (Triiodothyronine) is needed in patients who have clinical evidence for hyperthyroidism, in whom the usual thyroid profile result is reported as normal or borderline. The T3 Total test is recommended for patients with supraventricular tachycardia, for patients with fatigue and weight loss not otherwise explained, or for patients with proximal myopathy who also have T4 levels that are not elevated.