The synacthen test is a commonly performed endocrine test; we have looked at whether we overuse this test. Of 150 synacthen tests performed in one year 52 were randomly selected for audit. 19 were undertaken for symptoms alone (Group 1); 16 for a low random cortisol (below 261 nmom/l Group 2); 17 for electrolyte disturbances (either low sodium, high potassium or both Group 3). 3 in Group 2 and 1 in Group 1 were abnormal but in no patient with a random cortisol above 250 nmol/L. A further 4 had stressed responses (3 in Group 1 and 1 in Group 2) with a high basal cortisol (668 to 1293) and reduced incremental rise.
Preceeding the test TFTs (48/52) and U and Es (50/52) were performed in most cases; random cortisol was measured in only 6/19 in Group1 (but not in the abnormal response) and 10/17 in Group 3 (where 3 were below 250 nmol/L), thus not following the protocol.
Although only a low number of tests (4/52 7.7%) were abnormal a test with a normal result is not entirely inappropriate, but failure to follow the protocol could have reduced the number of tests in symptomatic patients. This could have resource savings for our unit.