This disease is marked by increased extravascular hemolysis, with laboratory findings including increased lactate dehydrogenase and decreased or absent haptoglobin in both warm and cold AIHA, and positive Coombs test. Clinically, jaundice or dark urine present in approximately one-third of the cases, and most of the symptoms are related to anemia.Other less commonly observed causes of hemolysis include:

Hemolysis secondary to drug toxicity
Thalassemia minor
Congenital dyserythropoietic anemiaThe above list is not exhaustive, and rare causes of hemolysis such as Bartonella infection, hemolysis due to transfusion reactions, and microangiopathic hemolytic anemia should be suspected when symptoms specific to those causes manifest. Pathophysiology
Bilirubin overproduction
The mechanisms by which bilirubin is overproduced in hemolytic jaundice can be understood in relation to the two major sites of hemolysis: intravascular and extravascular.During intravascular hemolysis, red blood cells are broken down within the vasculature, allowing hemoglobin from the ruptured red blood cells to form haptoglobin-hemoglobin complexes with haptoglobin, which will be internalized and degraded by hepatocytes and the spleen. If the degree of hemolysis is abnormally high, the unbound hemoglobin is converted to methemoglobin from which the heme moiety is bound to hemopexin or to albumin, and both heme-hemopexin and heme-bound albumin are internalized by hepatocytes and subsequently degraded to bilirubin. During extravascular hemolysis, red blood cells are destroyed by phagocytosis by macrophages in the reticuloendothelial system and digested by phagosomes.
Unlike alcohol, the onset and disappearance are near instantaneous. A diver may be quite clear-headed at 20 meters, and yet giddy and silly at 30 meters. Ascending to 20 meters will almost instantly clear the head. High pressure nervous syndrome (HPNS)
Barotrauma
Barotrauma is injury caused by pressure effects on gas spaces. This may occur during ascent or descent. The ears are the most commonly affected body part. The most serious injury is lung barotrauma, which can result in pneumothorax, pneumomediastinum, pneumopericardium, subcutaneous emphysema, and arterial gas embolism. All divers, commercial air travelers, people traveling overland between different altitudes, and people who work in pressurized environments have had to deal with some degree of barotrauma effect upon their ears, sinuses, and other air spaces. At the most extreme, barotrauma can cause ruptured eardrums, bleeding sinuses, exploding tooth cavities, and the lung injuries described above. This is the reason why divers follow a procedure of not holding their breath during ascent. By breathing continuously, they keep the airways open and avoid pressure differences between their lungs and ambient pressure. Arterial gas embolism (AGE)
Arterial gas embolism (AGE) is a complication of lung barotrauma of ascent. It occurs when breathing gas is introduced to the circulation on the arterial side via lung over-pressure trauma. AGE can present in similar ways to arterial blockages seen in other medical situations. Affected people may suffer strokes, with paralysis or numbness down one side; they may suffer heart attacks; they may suffer pulmonary embolism with shortness of breath and chest pain.