Pathogenesis & management of delayed orthostatic hypotension in patients with Chronic Fatigue Syndrome (CFS)

The relationship between orthostatic hypotension and chronic fatigue
syndrome (CFS) has been reported previously. To study the
pathogenesis and management of delayed orthostatic hypotension
in patients with CFS, a case comparison study with follow-up
of 8 weeks has been designed.

A group of 78 patients with CFS (mean age 40 years;
49% men and 51% women), who fulfilled the
Centre for Disease Control and Prevention criteria were
studied. There were 38 healthy controls (mean age 43 years;
47% men and 53% women). At entry to the study each subject
underwent an upright tilt-table test, and clinical and
laboratory evaluation. Patients with orthostatic hypotension
were offered therapy with sodium chloride (1200 mg) in a
sustained-release formulation for 3 weeks, prior to
resubmission to the tilt-table testing, and clinical and
laboratory evaluation.

An abnormal response to upright tilt was observed
in 22 of 78 patients with CFS. After sodium chloride
therapy for 8 weeks, tilt-table testing was repeated
on the 22 patients with an abnormal response at baseline. Of
these 22 patients, 10 redeveloped orthostatic hypotension,
while 11 did not show an abnormal response to the test and
reported an improvement of CFS symptoms. However, those CFS
patients who again developed an abnormal response to tilt-test
had a significantly reduced plasma renin activity (0.79
pmol/ml per h) compared both with healthy controls (1.29
pmol/ml per h) and with those 11 chronic fatigue patients (1.0
pmol/ml per h) who improved after sodium chloride therapy (p =

In conclusion, in our study CFS patients who did not
respond to sodium chloride therapy were found to have low
plasma renin activity. In these patients an abnormal
renin-angiotensin-aldosterone system could explain the
pathogenesis of orthostatic hypotension and the abnormal
response to treatment.

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