Hyperoxaluria
| Classification according to ICD-10 | |
|---|---|
| E74.8 | Other specified disorders of carbohydrate metabolism oxaluria |
| ICD-10 online (WHO version 2019) | |
Under hyperoxaluria (also: oxaluria , oxalosis ) is defined as the rise and increased excretion of oxalic acid in the urine.
to form
A distinction is made between two forms of hyperoxaluria: the rare primary hyperoxaluria is an enzyme defect, the secondary hyperoxaluria occurs in the context of other underlying diseases.
Primary hyperoxaluria
Oxalate is an end product of metabolism and is almost completely excreted in the urine as long as the kidney function is sufficient. With extremely high oxalate excretion, as is common in primary hyperoxaluria (PH), the urine is always oversaturated with calcium oxalate (CaOx). This leads to deposits of these crystals in the kidney tissue ( nephrocalcinosis ) or to stone formation in the urinary tract . Both trigger a chronic inflammatory and scarring reaction and ultimately impaired kidney function.
In addition to the deposition of CaOx in the kidneys, increasing impairment of kidney function leads to systemic oxalosis, which affects, among other things, the eyes , heart muscle , blood vessel walls , skin , bones and the central nervous system . As a result, it comes in addition to renal impairment at different oxalosis typical organ diseases such as blindness , heart rhythm disturbances , no longer treatable anemia and oxalate bone disease and possibly death.
The clinical course of primary hyperoxalurias varies greatly, and there is no real genotype / phenotype correlation. The manifestation ranges from the mere occurrence of individual kidney stones in old age to impaired kidney function in early childhood. The variability can also be high within the family.
There are three forms of primary hyperoxaluria (type I, type II and type III) and there are also unclassified forms.
Primary hyperoxaluria type I.
In primary hyperoxaluria type I is a rare, autosomal - recessive inherited metabolic disease. The incidence is 0.4–1: 10,000, the disease being said to occur most frequently in Arabs and in Iran. This is a defect of peroxisomal liver enzyme glyoxylate - aminotransferase (locus 2q36-q37). The enzyme converts glyoxylate into glycine . As a result, there is an increase in oxalic acid. There are massive deposits of oxalic acid in various tissues, including the kidneys, which leads to chronic kidney failure . Oxalic acid can precipitate in the urine and then lead to urolithiasis . This can then be accompanied by fever, hematuria and renal colic . In the course of the disease, the urinary tract can become completely blocked and acute kidney failure can occur. Terminal kidney failure occurs in around half of the patients within 15 years . The concentration of oxalic acid in the blood then increases. Now it is increasingly deposited in various tissues. The following malfunctions occur as a result of the deposits:
- conduction disorders in the heart ,
- in the vascular system high blood pressure , distal gangrene ,
- Limited mobility and pain in the joints .
The first symptoms can appear in the 1st year of life, half of the patients are symptomatic by the 5th year of life.
Primary hyperoxaluria type II
The PH II is based on a deficiency of the glyoxylate reductase / hydroxypyruvate reductase (GRHPR) that occurs throughout the body. Here, too, oxalate accumulates as a result of the lack of degradation of glyoxylate. In addition, with PH II there are usually increased levels of L-glycerate in the urine.
Other subtypes of PH are likely to occur, since up to 20% of patients with the typical PH phenotype have normal AGT and GRHPR activities and normal sequence findings for AGXT and GRHPR (11, 3). The etiology of these subtypes was previously completely unknown. A new gene PH III localized on chromosome 10 has recently been described (DHDPSL, hydroxyproline metabolism).
Another PH gene was found.
Primary hyperoxaluria type III
Primary hyperoxaluria type 3 (PH3) is characterized by increased oxalate and glycolate in 5% of patients, with the enzyme activities of AGT and GR being normal. PH3 is caused by mutations in the HOGA1 gene, which codes for 2-keto-4-hydroxy-glutarate aldolase.
Secondary hyperoxaluria
Secondary hyperoxaluria can occur after consuming large amounts of spinach, rhubarb or cocoa-containing products, as these foods contain a particularly high amount of oxalic acid.
therapy
The treatment consists initially of high fluid intake and the administration of inhibitors of crystal formation such as citrate , bicarbonate and magnesium . In addition, attempts are made to keep the urine alkaline so that the oxalate stones do not fall out in the urinary tract. By substituting pyridoxine , the oxalate production can potentially be reduced in vitamin B6-sensitive patients. Early and aggressive conservative therapy can delay the course of the disease.
A kidney transplant alone is not enough as therapy; a combined liver and kidney transplant must take place, which is probably the treatment of choice for young children.
Web links
- Macroscopic image of a kidney stone in hyperoxaluria on PathoPic
- S2 guidelines on diagnosis, therapy and metaphylaxis of urolithiasis
- Bernd Hoppe: Primary and Secondary Hyperoxaluria - a short introduction to the subject . (PDF; 285 kB) on ph-selbsthilfe.org
- Primary hyperoxaluria on ph-selbsthilfe.org
- The Oxalosis & Hyperoxaluria FUNDATION (OHF)
- European Hyperoxaluria Consortium on O | X | A | L | EUROPE
Individual evidence
- ↑ medical-genetics.de
- ↑ Medizinische-Genetik.de
- ↑ Sonia Fargue, et al .: Effect of conservative treatment on the renal outcome of children with primary hyperoxaluria type 1 . In: Kidney International . 76, No. 7, October 2009, pp. 767-773. doi : 10.1038 / ki.2009.237 . PMID 19571789 .
- ↑ orpha.net
