Earlier responses in the delay of Korotkoff sounds as compared to the Achilles reflex time in rapid changes of thyroid function in man

In rapidly changing thyroid state Rodbard's Q-Kd interval (reflecting heart contractility) changes more rapidly, than ART (reflecting skeletal muscle contractility). After withdrawal of substitutive therapy in athyreotic patients the Q-Kd intervals prolongs more rapidly than ART and during intensive treatment of hypothyroidism the Q-Kd interval shortens more rapidly that ART. A more rapid metabolic turnover in heart muscle in comparison with skeletal muscle is proposed as suitable explanation. Practical consequences for early diagnosis of hypothyroidism and for instant functional diagnosis of thyroidal disorders are stressed.