A critical evaluation of the tendon reflex measurement as an index of thyroid function.

IT IS now accepted that the tendon reflex is prolonged in patients with hypothyroidism. Chaney (1924) was the first worker to record the Achilles tendon reflex and prove what had previously been detected clinically. Since then several systems have been devised for recording the ankle jerk (Lambert, Underdahl, Beckett, and Mederos, 1951; Lawson, 1958; Gilson, 1959; Sharpe, 1961; Smart and Robson, 1963; Moulopoulos, Koutras, and Kralios, 1964). Two of these methods, the Photomotograph (Gilson, 1959) and the Kinemometer (Larson, 1958) are available commercially and are widely used in the United States. Although many authors have confirmed Chaney's original findings in adults (Lambert and colleagues, 1951; Lawson, 1958; Mann, 1963; Sherman, Goldberg and Lawson, 1963) and in children (Bowers, Gordon and Segaloff, 1959), the value of measuring the Achilles tendon reflex as an index of thyroid function is still in dou'bt. Measurement of the tendon reflex is a test which can be performed rapidly and which causes the patient little inconvenience. The result is available immediately and is not invalidated by the administration of thyroid replacement therapy or antithyroid drugs. The test would therefore be potentially useful if it were found to be reliable and diagnostic. In this paper an attempt is made to assess the reliability and usefulness of the test in patients suspected of being hypothyroid or who were thyrotoxic. Results obtained over a period of more than three years are summarised.