ABSTRACT
To study the possible disturbances of renin-angiotensin II Aldosterone system [RAAS] in chronic obstructive pulmonary disease [COPD] patients, this work was conducted. It included 45 COPD and 10 healthy control volunteers. Both plasma renin activity [PRA] and plasma aldosterone [PA] were measured in patients and controls by radioimmunoassay [RIA] and the results were plotted against clinical and functional data as well as serum and urinary electrolytes. In COPD patients, PRA and PA levels [means +/- SD were 4.4 +/- 1.16 ng/ml/h and 132 +/- 44pg/ml us 1.2 +/- 0.26 ng/ml/h. and 65 +/- 3pg/ml respectively, were significantly higher than those of controls, and positively correlated with each other. There was no effect of sex, body weight or age on the RAAS, while a significant positive correlation between smoking and PRA was found. Greater RAAS stimulation was observed in the presence of peripheral edema and with advancement of hypercapnia, hypoxemia and airway obstruction. Inability to excrete sodium, in urine was the most prominent electrolyte disturbance in advanced COPD. Mechanical ventilation was associated with further stimulation of RAAS. In conclusion, RAAS is frequently stimulated in COPD patients especially in advanced stages of the disease, leading to a state of secondary hyperaldosteronism of the hyperreninemic type that may contribute to sodium retention and edema formation. Hypercapnia and, to lesser degree, hypoxemia may be the most accused predisposing factors for RAAS stimulation