Ochronosis is the muscoskeletal manifestation of alkaptonuria – a rather rare (one in 200,000 births) inherited disorder of protein metabolism characterized by an inability of the body to metabolize the amino acids tyrosine and phenylalanine. It affects especially the large joints (hip, knees and vertebral column) by a progressive degenerative arthrosis.
The outward signs are the ocular (eye) and the skin pigmentations, the genito-urinary calculi (stones) and cardiovascular ochronosis (especially the aortic valve). The symptoms mostly begin within the third or fourth decade.
It was Scribonius who described the first known case of ochronosis in 1584. He mentioned a schoolboy who passed urine black as ink. In 1902, Albrecht and Zdareck discovered the link with alkaptonuria. The incidence of alkaptonuria is 1 per million with the highest prevalence in Slovakia by inbreeding.
There is no cure for ochronotic arthropathy. The enzyme deficiency is as yet untreatable (gene therapy in the future?) Some physicians prescribe high doses of ascorbic acid to prevent the interaction of the ochronotic pigment with the tissues. Unfortunately, the progress of the disease is not interrupted by this treatment. There only exists a symptomatic treatment: analgetics, NSAID, physical therapy, orthopaedic supports and intra-articular corticoid infiltration, especially in the knee. Finally, arthroplasty of the hip and knee is often necessary.
Signs, symptoms & indicators of Ochronosis / Alkaptonuria
Blue and brown fingernails
Dark urine color
Although a very rare disease, the main outward symptom of ochronosis is black urine.
Key
| Weak or unproven link |
| Strong or generally accepted link |
Glossary
Protein
Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.
Metabolism
The chemical processes of living cells in which energy is produced in order to replace and repair tissues and maintain a healthy body. Responsible for the production of energy, biosynthesis of important substances, and degradation of various compounds.
Tyrosine
A nonessential amino acid but may be essential for individuals with certain diseases or nutritional concerns. May be important for neurotransmitter synthesis and mood regulation. May be useful for depression, allergies and addictive states.
Phenylalanine
Essential amino acid needed for the normal growth of infants and children. It is also needed for normal protein use all through life. Precursor to tyrosine which is used to manufacture certain hormones (epinephrine, norepinephrine, dopa, dopamine) which are important for the transmission of nerve impulses. As neurotransmitters, these substances are believed to influence mood, appetite control and memory. It is found in large amounts in milk, eggs, and other common foods.
Arthrosis
Joint disease.
Cardiovascular
Pertaining to the heart and blood vessels.
Enzymes
Specific protein catalysts produced by the cells that are crucial in chemical reactions and in building up or synthesizing most compounds in the body. Each enzyme performs a specific function without itself being consumed. For example, the digestive enzyme amylase acts on carbohydrates in foods to break them down.
Vitamin C
Also known as ascorbic acid, Vitamin C is a water-soluble antioxidant vitamin essential to the body's health. When bound to other nutrients, for example calcium, it would be referred to as "calcium ascorbate". As an antioxidant, it inhibits the formation of nitrosamines (a suspected carcinogen). Vitamin C is important for maintenance of bones, teeth, collagen and blood vessels (capillaries), enhances iron absorption and red blood cell formation, helps in the utilization of carbohydrates and synthesis of fats and proteins, aids in fighting bacterial infections, and interacts with other nutrients. It is present in citrus fruits, tomatoes, berries, potatoes and fresh, green leafy vegetables.
NSAID
Non-steroidal anti-inflammatory drug.