Organic aciduria
From WikiLectures
Organic acidurias are a group of several dozen diseases with a common characteristic: the excretion of carboxylic acids in the urine . Organic acids accumulate in the body when the metabolism is disturbed, especially amino acids, then fatty acids and carbohydrates, rarely other substances.
Heredity:
Pathogenesis:
- disorder of the cytosolic, mitochondrial or peroxisomal metabolic pathway (enzyme deficiency, cofactor deficiency)
- substrate accumulation prior to failure
Symptoms:
- they are different according to the type of aciduria, often non-specific
- a strange smell is highly suspicious
- often metabolic acidosis
- often hyperammonemia
Forms:
- Acute neonatal
- severe disorder of intermediary metabolism
- manifests itself in the first days or weeks of life
- Intermittent
- partial deficiency of an enzyme that is sufficient for intermediate metabolism under normal conditions
- the provoking stimulus is increased catabolism (e.g. surgery), increased protein intake, prolonged starvation
- they are manifested by attacks of acute encephalopathy, acidosis, hypoglycemia
- Chronically ongoing
- less common, progressive, difficult to influence
- CNS disorders
The organic acidurias investigated as part of the nationwide newborn screening in the Czech Republic include:
- glutaric aciduria type I (GA I)
- isovaleric aciduria (IVA)
- leucinosis (MSUD)
- The last one is propionic acidemia , which is not in the screen
Methylmalonic acidemia
- It belongs to the group of organic acidurias
- It is a disorder of the Methylmalonyl-Coa mutase enzyme
- inheritance is AR
- its non-hereditary form is caused by an excess of vitamin B12, which is a cofactor of the said enzyme
Clinical picture
- a short symptom-free period after birth
- then vomiting
- lethargy
- progressive impairment of consciousness
- brain edema
- liver and kidney failure
- children die under the guise of sepsis, bleeding, or shock
- in the acute stage - ketoacidosis and laboratory signs of liver and kidney failure
- glycine, valine, methionine and methylmalonic acid are higher in blood and urine
Diagnosis
- examination of organic AMK in urine and blood
- the exact type of defect will be determined by enzymatic examination of cultured fibroblasts
Therapy
- if suspected, protein intake should be stopped and muscle catabolism-glucose infusion must be avoided
- with early treatment the prognosis can be good
- in critically ill patients, we must use elimination methods for treatment: hemodialysis, hemodiafiltration, peritoneal dialysis and exchange transfusion (descending efficiency).
- a lifelong diet with a restriction of the amino acids isoleucine, valine, methionine and threonine with the addition of essential AMK and carnitine in food supplements is necessary.
Links
References
- HYÁNEK, Josef, et al. Hereditary metabolic disorders. 1.. edition. Prague: Avicenum, 1990. p. 342. ISBN 80-201-0064-4 .
- ↑ BENEŠ, Jiří. Study materials [online]. ©2007. [feeling. 2010-04]. < http://www.jirben.wz.cz/ >. HRODEK, Otto and Jan VAVŘINEC, et al. Pediatrics. 1st edition. Prague: Galén, 2002. ISBN 80-7262-178-5 .
