After preliminary investigation revealed that the outbreak was linked to intake of tryptophan, the U.S. Food and Drug Administration (FDA) recalled tryptophan supplements in 1989 and banned most public sales in 1990, with other countries following suit. This  FDA restriction was loosened in 2001, and fully lifted in 2005. Since the initial ban on L-tryptophan, a normal metabolite of the compound in mammals, 5-hydroxtryptophan (5-HTP) has become a popular replacement dietary supplement. See also
Toxic oil syndrome

References


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Myoglobinuria is the presence of myoglobin in the urine, which usually results from rhabdomyolysis or muscle injury. Myoglobin is present in muscle cells as a reserve of oxygen. Signs and symptoms
Signs and symptoms of myoglobinuria are usually nonspecific and needs some clinical prudence. Therefore, among the possible signs and symptoms to look for would be:
Swollen and painful muscles
Fever, nausea
Delirium (elderly individuals)
Myalgia
Dark urine
Calcium ion loss

Causes
Trauma, vascular problems, malignant hyperthermia, certain drugs and other situations can destroy or damage the muscle, releasing myoglobin to the circulation and thus to the kidneys. Under ideal situations myoglobin will be filtered and excreted with the urine, but if too much myoglobin is released into the circulation or in case of kidney problems, it can occlude the kidneys filtration system leading to acute tubular necrosis and acute kidney injury. Other causes of myoglobinuria include:

McArdles disease
Phosphofructokinase deficiency
Carnitine palmitoyltransferase II deficiency
Malignant hyperthermia
Polymyositis
Lactate dehydrogenase deficiency
Adenosine monophosphate deaminase deficiency type 1
Thermal or electrical burn

Pathophysiology
Myoglobinuria pathophysiology consists of a series of metabolic actions in which damage to muscle cells affect calcium mechanisms, thereby increasing free ionized calcium in the cytoplasm of the myocytes (concurrently decreasing free ionized calcium in the bloodstream). This, in turn, affects several intracellular enzymes that are calcium-dependent, thereby compromising the cell membrane, which in turn causes the release of myoglobin. Diagnosis
After centrifuging, the urine of myoglobinuria is red, where the urine of hemoglobinuria after centrifuge is pink to clear. Treatment
Hospitalization and IV hydration should be the first step in any patient suspected of having myoglobinuria or rhabdomyolysis.