brown yellow disease
Introduction
Introduction to brown yellow disease Ochunosis is due to the lack of homogentisate oxidase in the body, so that the intermediate metabolite of phenylalanine and tyrosine (uric acid) can not be further oxidized and decomposed, accumulating in the body, making the skin, sclera, The cartilage color darkens, while uric acid causes pigmentation of cartilage and other connective tissues, and degenerative arthritis of the spine and peripheral large joints. On the other hand, urinary acid is excreted in the urine, and is alkalized and oxidized in the urine to darken the urine, so it is also called black uric acid (Alkaptonuria). basic knowledge The proportion of sickness: 0.01%-0.05% Susceptible people: no specific population Mode of infection: non-infectious Complications: aortic stenosis prostatitis
Cause
Cause of brown yellow disease
Cause (50%):
The disease is a rare autosomal genetic disease whose exact autosomal variation is unclear. Connective tissue and cartilage blackening are the basic pathological changes of the disease. Uric acid can be deposited on the skin, cornea, cartilage, etc., making these organs darken, involving cartilage can lead to exfoliation of subchondral bone.
Pathogenesis (20%)
The metabolic pathway in which phenylalanine and tyrosine are converted to acetoacetate (Figure 1), and uric acid (HGA or 2,5-dihydroxyphenylacetic acid) is the last compound in the metabolic pathway that contains a complete aromatic ring. The enzyme that catalyzes the cleavage of the aromatic ring is urinary oxidase, which is normally present in the soluble part of the liver and kidney tissue. This enzyme is highly specific for the decomposition of uric acid, and tissues other than liver and kidney do not contain this. The enzyme, the patient, the liver, and the kidney completely lack the activity of the enzyme, and the result is that the uric acid is not decomposed into acetoacetate and fumaric acid, so that other metabolic mechanisms are needed to treat the uric acid, the kidney to the urine. The clearance rate of erythric acid is very high, and the renal tubule actively secretes urinary acid. Once the kidney excretes the uric acid, it will gradually oxidize to form a polymer that can cause urinary discoloration. Currently, the deposition of uric acid on the tissue causes brown. The mechanism of yellow disease is still not clear. Uric acid has a tendency to deposit on the skin and cartilage. In these tissues, the substance can be combined by physical attraction. In addition, the decomposition product of uric acid can irreversibly bind to connective tissue. , forming a polymer that can cause pigmentation, the texture is weak after the coloration, may break, resulting in degenerative lesions of the intervertebral disc and joint, in addition, uric acid can also directly act on collagen by inhibiting lysyl hydroxylase synthesis.
Prevention
Brown yellow disease prevention
The disease is a rare hereditary disease. Foreign reports have a prevalence rate of 3 to 5 per million population. Because the uric acid is easily deposited on the cartilage, the joint is denatured. As a hereditary disease, this disease has no effective drug prevention, so early detection is the key to prevention and treatment. Care should be taken to avoid marriage by close relatives, pre-marital counseling, fertility counseling and regular pregnancy tests to reduce the incidence of this disease.
Complication
Brown yellow disease complications Complications aortic stenosis prostatitis
After mild traumatic injury of the knee joint, it can cause fluid accumulation in the joint cavity. The synovial fluid is non-inflammatory, mainly containing monocytes. Articular microscopy can be seen in the synovial membrane black stain, and joint contracture can gradually occur after the joint fluid disappears. Some patients may have heart valve disease, mainly aortic valve stenosis, and male patients may develop chronic prostatitis.
Symptom
Symptoms of brownish yellow disease Common symptoms Urine is black uric acid, joint pain, calcification, lower back stiffness and pain, ear, nose, cartilage, blue joint, contracture, spine, physiological curvature, disappearance, kidney stone, synovial black stain
(1) Joint disease: The most serious complication of this disease is joint disease. Unlike rheumatoid arthritis, this disease mainly invades the large joints such as the spine and shoulders, hips, etc., and the hand and foot joints are rarely affected. Male patients have early and severe onset, knee joints are most often involved, and the degree of damage is also the heaviest. Spinal lesions are also the most common bone and joint damage in this disease, often manifested as lower back stiffness and pain. The lesions first occur in the lumbar spine. The development of the condition can affect the thoracic vertebrae, hinder the movement of the spine, and the physiological curvature of the spine disappears. Disc herniation and calcification are also characteristic features of this disease. The typical patient is a forward-dipping duck gait. After the mild knee injury of the affected knee joint, it can cause joints. The effusion and synovial fluid are non-inflammatory, mainly containing monocytes, and the synovial membrane is black-stained by arthroscopy. The joint contracture can gradually occur after the joint fluid disappears.
(2) Skin lesions: caused by the deposition of urinary acid pigment particles in the dermis and sweat glands, mostly brown in the tip of the nose, at the junction of the ear and rib-cartilage, or in the shape of a butterfly on the bridge of the nose and cheeks, armpits And the perineum is a sweaty gland, often dark brown or blue-black, can make the clothes close to these parts brown, and occasionally the nails can also be blue-gray, often accompanied by auricular stiffness and calcification, brown-yellow pigment Swelling can sometimes occur in extraocular tissues, such as the sclera, conjunctiva, and cornea. The sclera is brown and is usually limited to the exposed parts of the cleft palate.
(3) Others: Some patients may have heart valve disease, mainly aortic valve stenosis, male patients with longer course of disease may develop chronic prostatitis, which is caused by the formation of stones in the alkaline secretion of the prostate. The patient can have porous black kidney stones.
Examine
Browning disease check
X-ray inspection
(1) Spinal changes: prominent thoracic vertebrae, excessive curvature of the lumbar spine, osteoporosis of the spine, spur formation at the edge of the vertebral body, extensive degeneration of the intervertebral disc, and stratified calcification, with a special increase in the density of the flat thin ellipse The double transverse calcification shadows are parallel to each other, and there is a translucent layer in the middle interval. The intervertebral disc is widely affected, especially in the lumbar vertebrae, and the intervertebral space is obviously narrowed.
(2) Both the shoulder and the knee joint can undergo degenerative changes. The tendon ligament can have calcification, the ankle joint can be narrowed, the joint under the bone is hardened, the cartilage of the pubic symphysis is also calcified, and there is bone erosion under the cartilage. Bone, acetabular, large trochanter, small trochanter, tendon of the ischial tuberosity and soft tissue around the joint can also occur calcification.
2. Special examination of uric acid: The uric acid can be measured by spectrophotometer, and the blood and urine uric acid content can also be determined by special enzymes.
Diagnosis
Diagnosis and diagnosis of brownish yellow disease
In the differential diagnosis, other causes of urinary blackening, such as hematoporphyria, myosinuria, bilirubinuria, and hematuria, should be excluded. It is not difficult to distinguish from brownish yellow disease based on the clinical characteristics of these diseases and related laboratory tests. Long-term use of mepacrine (Api) can cause brown pigmentation-like pigmentation, and clinical care should be taken not to confuse this iatrogenic pigmentation with brownish yellow disease. Multiple application of phenol (carbolic acid) for the treatment of skin ulcers can also cause yellow pigmentation, which should be noted.
