Pediatric Disorders of Orthostatic Intolerance.

Orthostatic intolerance (OI), having difficulty tolerating an upright posture because of symptoms or signs that abate when returned to supine, is common in pediatrics. For example, ∼40% of people faint during their lives, half of whom faint during adolescence, and the peak age for first faint is 15 years. Because of this, we describe the most common forms of OI in pediatrics and distinguish between chronic and acute OI. These common forms of OI include initial orthostatic hypotension (which is a frequently seen benign condition in youngsters), true orthostatic hypotension (both neurogenic and nonneurogenic), vasovagal syncope, and postural tachycardia syndrome. We also describe the influences of chronic bed rest and rapid weight loss as aggravating factors and causes of OI. Presenting signs and symptoms are discussed as well as patient evaluation and testing modalities. Putative causes of OI, such as gravitational and exercise deconditioning, immune-mediated disease, mast cell activation, and central hypovolemia, are described as well as frequent comorbidities, such as joint hypermobility, anxiety, and gastrointestinal issues. The medical management of OI is considered, which includes both nonpharmacologic and pharmacologic approaches. Finally, we discuss the prognosis and long-term implications of OI and indicate future directions for research and patient management.

Low iron storage and mild anemia in postural tachycardia syndrome in adolescents.

OBJECTIVE: We reported low iron storage in neurally mediated syncope (NMS). While reduced red cell mass indicative of anemia has been reported in POTS, iron indices and hemoglobin (Hb) data were not reported. We investigated whether POTS, like NMS, is associated with low iron storage and anemia. METHODS: Thirty two children evaluated in 2007 and 2008 for probable POTS by a standing or tilt test or both at Texas Children's Hospital were included in a retrospective study. We measured serum ferritin (SF) and Hb values. We defined iron deficiency as SF < 12 µg/L, low iron storage as SF ≤ 25 µg/L, anemia as low Hb values for age and sex, and POTS as ≥2 symptoms of orthostatic intolerance >3 months and increased HR of >30 BPM or HR of >120 BPM within 10 min of standing or 70° tilt. RESULTS: Twenty four children had POTS, ages 12-18 years, 17 (71 %) were females. Value range (median) of SF 2-289 µg/L (25), Hb 11.5-14.6 (12.5) in females and 12-15.9 g/L (13.6) in males. Patients with POTS, when compared with normal US pediatric population had higher prevalence of low iron storage (50 vs. 14 %), iron deficiency (25 % of teenage girls vs. 9 %, and 16 % of teenage boys vs. 1 %), and anemia (18 % of teenage girls vs. 1.5 %, and 43 % of teenage boys vs. 0.1 %). INTERPRETATION: Low iron storage and mild anemia are associated with POTS suggesting that low iron storage is a potentially pathophysiologic factor in both POTS and NMS.

Low iron storage in children and adolescents with neurally mediated syncope.

OBJECTIVE: To investigate whether neurally mediated syncope (NMS) is associated with low iron storage or serum ferritin (SF). STUDY DESIGN: 206 children evaluated between 2000 and 2004 for probable syncope at a tertiary care Pediatric Neurology Clinic were included in a retrospective study. Serum ferritin (SF), iron, total iron binding capacity, and hemoglobin were measured prospectively after initial history taking and physical examination, along with other diagnostic testing. We defined iron deficiency (ID) as SF <12 microg/L, and low iron storage as SF