Improved diagnosis and management of hyper- and hypothyroidism by timing the arterial sounds.

"Sphygmo-Recording," a non-invasive method for timing the arterial pulse wave contour provides an objective measure of responses to medication in patients with hyper- and hypothyroidism. The QKd interval, i.e., the interval from the onset of the QRS complex (Q) to the onset of the Korotkoff sounds (K) at the brachial artery when the sphygmomanometer cuff is at diastolic pressure (d) is the QKd interval. QKd is normally 205 +/- 12 msec. In the hyperthyroidism the QKd interval may be shortened to 110 msec. In hypothyroidism the QKd interval may be prolonged to 320 msec. Changes in QKd parallel changes in clinical status and serum total T4 and T3, measured by radioimmunoassay. QKd can be used as an objective guide to antithyroid therapy in hyperthyroidism and replacement therapy with thyroid hormone in hypothyroid individuals.