Current Status of Low Dose Overnight Dexamethasone Supression Test (LODST)

Abstract

Introduction: Low Dose Overnight Dexamethasone Supression Test (LODST) is a diagnostic tool for spontaneous Cushing’s Syndrome (CS). A LODST negative excludes CS. But there are 2 exceptions - testing during silent period of Cyclic Cushing’s Disease (CD) or a false negativity by one mg dexamethasone in mild CD. Method: We analyzed age and sex data of 154 LOSDT to see their risk association for CS. Result: The detection rate of CS by LOSDT is 26% and with Cortisol (211.27 to 373.69 nmol/L as 95% CI). Among the cases, 29.2% are pediatric and 70.8% are female. CS group do not differ from rest in sex and age group distributions (sig.> 136) but CS is older group with a mean difference of 2.46 - 13.31 years (sig 005). Logistic equation documented CS is a different population (sig 000) and which is influence by their age (sig 021) but not by sex or age group (sig > 743). Therefore, age is an independent risk factor for CS. Conclusion: We opine to use LODST as the first tool for CS. And LODST negative cases to be evaluated by newer imaging and biochemical tests. Only in imaging positive are to be managed as per guideline(s) for incidentaloma. Both negative cases are to be enrolled in follow up if age > 30 years or symptoms score suggest CD and rest are to be excluded. Cumulative diagnostic and outcome data will then may be used to formulate cost-effective management policy for CS.