Spot urine cortisol–creatinine ratio – A useful screening test in the diagnosis of Cushing's syndrome

INTRODUCTION: Although, there are several tests available, not one of them fulfils the criteria of being an ideal screening test. Continuing the search for an ideal screening test, we explored the use of urine spot cortisol-creatinine ratio as a novel method of evaluating patients with Cushing's syndrome. METHOD: A total of 35 subjects were studied and divided into 3 groups - 15 having cushings syndrome, 15 patients with obesity and 5 normal weight subjects. All patients with cushings syndrome were positive for the other screening tests. RESULTS: The mean (standard deviation) of cortisol:creatinine ratio among the 3 groups (cushings, obese and control subjects) was 36.00(24.74), 7.01(2.73) and 3.49(2.68) respectively. Using the cutoff of 12.27 nano mol/ micro mol(based on data of normal subjects) for the urine cortisol creatinine ratio we get a sensitivity of 93.75% and a specificity of 100%. Also the positive and negative predictive value as calculated with this cutoff is 100% and 93.3% respectively. CONCLUSION: In this study we found that UCCR is similar in both Obese and Non Obese subjects who did not have cushings syndrome. UCCR is significantly elevated in individuals with Cushing's syndrome as compared to those who do not have cushings syndrome. Also when a cut off of 12.27 nano mol/ micro mol was used this test had a higher sensitivity, however this test had a higher specificity at a cut off of 15.35.