Regulation of the renin-angiotensin-aldosterone system in fibromyalgia

Objective. To assess the function of the renin-angiotensin-aldosterone (RAA) system in women with fibromyalgia (FM) compared to healthy women. Methods. Women with FM [n = 14, age 41.0 +/- 7.2 yrs, body mass index (BMI) 26.4 +/- 5.4 kg/m(2)] and healthy women (n = 13, age 40.0 +/- 7.7 yrs, BMI 25.0 +/- 5.0 kg/m(2)) were placed on a low sodium diet (10 mEq sodium/day) for 5 days. After being supine and fasting overnight, subjects received an intravenous infusion of angiotensin H at successive doses of 1, 3, and 10 ng/kg/min for 45 min per dose. Blood pressure (BP), plasma renin activity (PRA), aldosterone, and cortisol were measured at baseline and after each dose of angiotensin II. Prior to sodium restriction, women with FM completed the Hopkins Symptom Checklist-90, which included a question grading the extent of dizziness/faintness on a scale of 0 (none) to 4 (extremely). Results. After dietary sodium restriction, baseline PRA, aldosterone, and supine BP were similar in healthy women and women with FM. Aldosterone and BP rose in response to infused angiotensin II; these responses did not differ significantly between healthy women and women with FM. In women with FM, symptoms of dizziness correlated inversely with BMI (r = -0.81, p < 0.001) and the systolic BP response to 10 ng/kg/min angiotensin II (r = -0.81, p < 0.001). Conclusion. The functioning of the RAA system, including the vascular response to angiotensin II, was intact in women with FM compared to healthy women. However, women with FM who complained of dizziness had a blunted vascular response to angiotensin II. This blunted vascular response may indicate intravascular volume depletion in women with symptoms of dizziness.