Introduction: Cushings syndrome(CS) is associated with high morbidity and mortality which warrants a good screening test that is less laborious. We explored the possibility of using urine spot cortisol:creatinine ratio (UCCR) as a new screening test for Cushings syndrome.
Aims and objectives: To study the efficacy of UCCR as a screening test for patients with Cushings syndrome.
To compare UCCR in patients with CS, obese and normal subjects.
Material and Methods:: This was a prospective study conducted over a period of 1 year (February 2011January 2012). All patients with CS (n=15) were recruited. We also included a subset of obese (n=15) and normal weight (n=5) subjects. All CS subjects underwent measurement of 24 h urinary free cortisol, midnight serum cortisol and plasma ACTH. An UCCR was measured in an early morning spot sample. Using 12.3 nmol/μmol (mean+2S.D.), based on an earlier study in normal subjects, as the cutoff for UCCR, the sensitivity, specificity, positive and negative predictive values were calculated.
Results: Forty per cent of the patients had Cushings disease, 33% had adrenal adenomas, 20% had ectopic ACTH producing tumours and 7% had adrenal carcinomas. The mean (S.D.) of UCCR (nmol/μmol) in the CS, obese and normal subjects were 7.0 (+2.7) and 3.5 (+2.7) respectively. There was a significant difference in the mean UCCR of patients with and without CS (obese and normal subjects), 36.0 (+24.7) vs 6.13 (+3.0) nmol/μmol (P<0.001).
Using 12.3 nmol/μmol as the cutoff for UCCR, the sensitivity, specificity, positive and negative predictive values were 93.7, 100, 100 and 93.3% respectively.
Conclusion:: With a cut off of 12.3 nmol/μmol, UCCR was found to have high sensitivity and specificity. This inexpensive, rapid, non-invasive test can easily be performed. However, it has to be validated in a larger population with Cushings syndrome.