aminoaciduria
Introduction
Introduction Amino aciduria: (hyperaminoaciduria) is a type of metabolic disease characterized by excessive amino acid excretion in the urine, which can be divided into pre-renal, renal and mixed. The treatment effects of various types of high amino aciduria vary widely. Some can achieve good results by strictly controlling the intake of the corresponding amino acids in the diet or supplementing certain vitamins. Some even take various measures to make the plasma amino acid level close to normal. It also does not improve clinical symptoms. Renal amino aciduria is a proximal tubular reabsorption of amino acid disorders that causes large amounts of amino acids to be excreted from the urine. The amino acids excreted from the urine are mainly glycine, taurine, methyl histidine and the like. In addition, serine, threonine, leucine, phenylalanine and the like may also be discharged in a small amount.
Cause
Cause
(1) The cause of the disease is a family hereditary disease, which is an autosomal recessive hereditary disease. Influencing factors include age, gender, diet, physiological changes, and heredity.
Causes and classification:
1. Physiological amino acid urine is caused by physiological changes.
2. Pathological amino acid urine caused by disease caused by amino acid urine:
(1) "prerenal" amino acid urine:
1 "spill" amino acid urine: such as phenylketonuria, maple sapuria, is caused by a certain amino acid metabolism defect.
2 "competitive" amino acid urine: such as hyperprolineemia, etc., caused by competition in the renal tubules with the amino acid of the same transport system.
(2) "Kidney" amino acid urine: caused by a defect in the transport of proximal convoluted tubules.
1 a single group of amino acid transport system defects: that is, the proximal tubules are defective in the transport system of a group of amino acids, and the group of amino acids are excreted from the urine, including lysine, arginine, ornithine, cystine, and guanidine. Amino acid, hydroxyproline, glycine, aspartic acid, glutamic acid, and the like.
2 groups of amino acid transport system defects: due to multiple functional defects in the proximal curved tube, a variety of amino acid urine, accompanied by diabetes, high phosphate urine, uric acid dysfunction, such as Fanconi syndrome, Lowe syndrome Wait.
(two) pathogenesis
Increased total excretion of amino acids in the urine or a significant increase in individual amino acid excretion is called amino aciduria. Amino acids are an important nutrient in the human body, and most of the amino acids in the body can be used to synthesize proteins. Amino acids in the plasma can be freely filtered out of the urinary tract into the original urine, most of which can be reabsorbed back into the blood through the proximal tubules. When renal tubular function declines, the amino acid excretion in the urine increases. There are many causes of amino aciduria, most of which are genetic diseases, and kidney damage caused by drugs or poisons. Pathological amino acid urine can be divided into spilled amino acid urine and renal amino acid urine. The former refers to an increase in blood amino acids, which exceeds the reabsorption capacity of the renal tubules; the latter is due to congenital tubular lesions such as Fanconi syndrome and hepatolenticular lesions.
Renal amino aciduria is a hereditary disease, including basic amino aciduria (cystineuria), neutral amino aciduria (Hartnup disease), other amino acid urine, etc., which is caused by a defect in the proximal convoluted tubule transport. Alkaline amino acid urine (cystineuria) is the most common amino acid urine, which is easy to form cystine stones and provides bare nuclei for oxalate stone formation. Neutral amino aciduria (Hartnup disease) is more common in children. Other iminoglycine urine, simple cystineuria, simple glycine urine, and dicarboxy amino acid urine are less common.
Examine
an examination
Related inspection
Adrenal MRI examination of adrenal CT examination of proline
Therefore, clinical examination of patients with amino aciduria:
First, physical examination:
Taking a medical history gives us a first impression and revelation, and also guides us to a concept of the nature of the disease.
Second, laboratory inspection:
Laboratory examinations must be summarized and analyzed based on objective materials and medical examinations, and several possible diagnostics are proposed, and then further examinations are performed to confirm the diagnosis.
Diagnosis
Differential diagnosis
The differential diagnosis of this disease is mainly related to the identification of double-base amino acid urinary disease, which is mainly distinguished by specific amino acids in urine.
Commonality
The common clinical manifestations of various amino acid urinary tracts are growth and development disorders. In addition to short stature, there are many degrees of mental retardation.
2. Characteristic performance
It varies with the type of amino acid urine:
(1) cystine urine (alkaline amino acid urine): the disease is the most common amino acid urine, easy to form cystine stones, providing bare nuclei for the formation of oxalate stones.
1 specific renal amino acid urine: there are a large amount of cystine and three dibasic amino acids in the urine, and the excretion of urinary cystine can be seen in the concentrated urine sediment, which is the diagnosis of this disease. Has important value. The isoforms of the three subtypes were positive for cystine, lysine, arginine and ornithine in the urine, and cysteine and lysine in the urine of type II and III patients were also positive.
2 cystine stones: urinary calculi are often an important clue for patients to obtain diagnosis, often causing repeated renal colic, hematuria, obstruction and secondary infection. The stone is positively reacted with sodium nitroprusside cyanide and can be used as a screening diagnostic test. If the amount of urinary cystine excretion is small and its concentration is below saturation, it is called acalculous cystinuria. Stoller et al. investigated a family member of a patient and found that the average urinary cystine concentration was 496 mg/gCr in 3 patients with stones on the same diet for 72 h or more; 6 patients had an average age of 50 years but no urinary calculi. The average patient's urinary cystine concentration was 364 mg/gCr; another 34 members had a slight increase in urinary cystine concentration (mean 151 mg/gCr), and only 2 members had an average age of 44 years, but urinary cystine concentration. normal. This study suggests that in each family of patients with severe cystinuria, there may be several patients with no calculus in patients with cystineuria.
3 short body, mental retardation: may be related to the loss of a large number of amino acids (especially lysine).
4 pyrrolidine and acridine urine.
5 other: a small number of patients often associated with hereditary hypocalcemia, hereditary pancreatitis, hyperuricemia and muscle atrophy.
(2) Tryptophan urinary (neutral amino acid urinary): due to insufficient formation of niacinamide, causing psoriasis-like skin damage and neurological symptoms such as Hartnup's disease. The disease is mostly ill or aggravated in children. Most patients develop symptoms at an early age, which is intermittent and spontaneously relieved in adulthood. Some patients become ill only in adulthood.
1 short stature: It is generally believed that young people may have short stature, which is caused by a large loss of the above amino acids from the urine and feces, causing nutritional disorders. However, according to the long-term dynamic observation of 15 children in Australia by Wilcken et al, the disease has little effect on the growth and development of children, and the height is only slightly affected, and the mental development is normal.
2 skin damage: light-sensing psoriasis-like rash, in the exposed parts of the body, the rash is aggravated after sun exposure. Mori et al reported a case of a 37-year-old adult onset, clinically only with neuropsychiatric symptoms and no skin changes.
3 neuropsychiatric symptoms: severe cases may have paroxysmal cerebellar ataxia, occasional psychiatric symptoms, can spontaneously relieve within a few weeks. Excessive activity and breastfeeding can exacerbate skin and nervous system symptoms. The disease has a good prognosis.
(3) tyrosine urine: can produce paroxysmal cerebellar ataxia and psychiatric symptoms. According to the above clinical history, family history and a large amount of cystine in the urine can be diagnosed. Quantitative analysis of urine chromatography is helpful for diagnosis and typing.
