[2] From 1953 to 1956, he worked as a surgeon for the Section on Clinical Endocrinology at the National Heart, Lung, and Blood Institute.
He was the first to show that Cushing's disease was caused primarily by an abnormality in the anterior pituitary rather than the adrenal glands.
He discovered a method for measuring aldosterone levels in urine and pioneered the use of spironolactone in the treatment of high blood pressure.
[3] Based on his research into paraneoplastic syndromes, he coined the term "ectopic hormone secretion".
[3] In 1983, the Vanderbilt University Medical Center established the Grant W. Liddle Award in his honor.