Gilbert's syndrome

Gilbert's syndrome is a common hereditary cause of increased bilirubin. The main symptom is jaundice caused by elevated levels of unconjugated bilirubin in the blood. Reasonable levels of bilirubin can be beneficial to the organism. Evidence is being gathered that suggests bilirubin can protect tissues against oxidative damage caused by free radicals. Statistical analysis of people with high normal or slightly elevated bilirubin levels in blood shows that they have a lower risk of developing cardiovascular diseases. In infants it is not very common for the spleen to destroy red blood cells faster than the liver can conjugate the bilirubin. The effect of this would be increased bilirubin levels in the blood plasma.

Orthostatic intolerance

Orthostatic intolerance occurs in some humans while standing upright. This action is a fundamental stressor and requires rapid and effective circulatory and neurologic compensations to maintain blood pressure, cerebral blood flow, and consciousness. When a human stands, approximately 750 mL of thoracic blood is abruptly translocated downward. People who suffer from orthostatic intolerance - OI lack the basic mechanisms to compensate for this deficit. Changes in heart rate, blood pressure, and cerebral blood flow that produce OI "may be related to abnormalities in the interplay between blood volume control, the cardiovascular system, the autonomic nervous system and local circulatory mechanisms that regulate these basic physiological functions.