Postural orthostatic tachycardia syndrome (POTS): a common but unfamiliar syndrome.

Postural orthostatic tachycardia syndrome (POTS) is a condition in which a change from a supine to an upright position causes an abnormally large increase in heart rate which may be accompanied by a variety of physical complaints. We report two cases illustrating the heterogeneity of this syndrome. We give an update on the etiology of POTS, which is still poorly understood, and its overlap with other syndromes such as chronic fatigue syndrome. Clinicians should be aware of POTS, a fairly common clinical entity, that can result in significant impairments to a patient's quality of life. Lifestyle measures (under which adequate fluid and salt intake, exercise) are a first line of treatment; if insufficient, pharmacotherapy can be considered to improve quality of life.

Dyggve-Melchior-Clausen syndrome with increased pipecolic acid in plasma and urine.

A child with the Dyggve-Melchior-Clausen syndrome associated with elevated pipecolic acid levels in plasma and urine is described. Other studies of peroxisomal function, including phytanic acid, very long-chain fatty acids, and plasmalogen synthesis, were normal. This disorder may represent an incompletely characterized defect in peroxisomal metabolism.

Autonomic dysfunction and adrenocortical unresponsiveness to ACTH.

A child is reported with adrenocortical unresponsiveness to ACTH and autonomic dysfunction. The latter consisted of cold extremities, progressive loss of tear production, the development of achalasia of the esophagus, pupillary dysfunction, and an abnormal histamine skin test. These findings suggest progressive parasympathetic denervation as a cause for the adrenocortical abnormality.