lines of evidence that support nature of ovarian hyperstimulation syndrome (OHSS) as "defective mineralocorticoid response" are cited, our hypothesis is tested clinically in both prophylaxis against and treatment of OHSS.

several studies state significant correlation between OHSS and activation of Renin-angiotensin-aldosterone system (RAAS), degree of activation of RAAS correlates with severity of OHSS. In OHSS there is a cascade of events that mainly involves capillary leak with resultant fluid shift and electrolytes imbalance, these consequences are more pronounced - according to our hypothesis - due to inadequate mineralocorticoid response/activity in susceptible individuals in the settings of high progesterone levels with its antimineralocorticoid property, OHSS can be interpreted as a (mineralocorticoid deficiency crisis) and may effectively be treated as being so, so we conducted this study to test the hypothesis in both treatment and prevention of OHSS.

Inclusion Criteria: patients undergoing ICSI who were considered at risk of developing OHSS:

• polycystic ovaries and/or previous history of OHSS, AMH > 40 pmol/L but patients were finally included in the study if serum E2 levels reached >3000 pg/ml on day of hCG trigger or at any stage of folliculometry
• age: 18-40

Exclusion Criteria:

• retrieval of less than 20 oocytes
• age less than 18 or above 40