Endocrine Abstracts

Cabergoline (CAB), a potent dopamine agonist, is one of the most effective neuromodulatory drug in the second line treatment of patients with Cushing’s disease (CD). The aim of the current study was to estimate the predictive value of the acute CAB administration on short and long term responsiveness to CAB treatment. Twenty CD patients (6 males, 14 females, 12–60 years) entered the study. The acute CAB test was performed evaluating serum cortisol every hour for 6 h after 1 mg CAB administration. Serum cortisol and urinary cortisol (UC) levels were evaluated at baseline and after three (short-term) and six (long-term) months of treatment with CAB (dose 1–9 mg weekly). Patients were considered responsive when UC levels were ≤50% compared with baseline after 3 months or normalized after 6 months of treatment. A ROC curve was performed to establish the cut-off of the percentage of serum cortisol percent reduction (%ΔC) which guaranteed the highest sensitivity (SS) and specificity (SP) in predicting the responsiveness after short and long-term CAB treatment. The positive and negative predicting values (PPV and NPV) were estimated at both 3 and 6 months of treatment. Ten of the 20 patients (50%) showed responsiveness after either 3 or 6 months. A direct correlation was found between %ΔC and the percentage of reduction of UC at 3 months (r=0.467; P=0.038), while no direct correlation was found between %ΔC and the percentage of reduction of UC at 6 months. The 18% (SS=100%, SP=67%) and 20% (SS=100%, SP=50%) were considered as the best %ΔC cut-offs of the acute test response to predict the chronic responsiveness at 3 and 6 months, respectively; using these values we obtained a PPV of 83% and a NPV of 100% after 3 months and a PPV of 67% and a NPV of 100% after 6 months of treatment. In conclusion, the acute CAB test is useful to predict short-term but not long-term responsiveness; on the other hand it is completely reliable to select patients non responders to chronic CAB treatment.