[Has this been posted already? I didn't find it when I did a forum search but might have missed it.] Neurohumoral and haemodynamic profile in postural tachycardia and chronic fatigue syndromes Luis E. Okamoto, Satish R. Raj, Amanda Peltier, Alfredo Gamboa, Cyndya Shibao, Andr Diedrich, Bonnie K. Black, David Robertson, and Italo Biaggioni http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3203411/ Abstract Several studies recognized an overlap between CFS (chronic fatigue syndrome) and POTS (postural tachycardia syndrome). We compared the autonomic and neurohormonal phenotype of POTS patients with CFS (CFSPOTS) to those without CFS (non-CFSPOTS), to determine whether CFSPOTS represents a unique clinical entity with a distinct pathophysiology. We recruited 58 patients with POTS, of which 47 were eligible to participate. A total of 93% of them reported severe fatigue [CIS (Checklist of Individual Strength), fatigue subscale >36], and 64% (n=30) fulfilled criteria for CFS (CFSPOTS). The prevalence of CFS symptoms (Centers for Disease Control and Prevention criteria) was greater in the CFSPOTS group, but the pattern of symptoms was similar in both groups. Physical functioning was low in both groups (RAND-36 Health Survey, 404 compared with 333; P=0.153), despite more severe fatigue in CFSPOTS patients (CIS fatigue subscale 511 compared with 433; P=0.016). CFSPOTS patients had greater orthostatic tachycardia than the non-CFSPOTS group (513 compared with 404 beats/min; P=0.030), greater low-frequency variability of BP (blood pressure; 6.30.7 compared with 4.81.0 mmHg2; P=0.019), greater BP recovery from early to late phase II of the Valsalva manoeuvre (183 compared with 112 mmHg; P=0.041) and a higher supine (1.50.2 compared with 1.00.3 ng/ml perh; P=0.033) and upright (5.40.6 compared with 3.50.8 ng/ml per h; P=0.032) PRA (plasma renin activity). In conclusion, fatigue and CFS-defining symptoms are common in POTS patients. The majority of them met criteria for CFS. CFSPOTS patients have higher markers of sympathetic activation, but are part of the spectrum of POTS. Targeting this sympathetic activation should be considered in the treatment of these patients.