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Treatment consists of dietary protein restriction, particularly leucine. During acute episodes, glycine is sometimes given, which conjugates with isovalerate forming isovalerylglycine, or carnitine which has a similar effect.
Elevated 3-hydroxyisovaleric acid is a clinical biomarker of biotin deficiency. Without biotin, leucine and isoleucine cannot be metabolized normally and results in elevated synthesis of isovaleric acid and consequently 3-hydroxyisovaleric acid, isovalerylglycine, and other isovaleric acid metabolites as well. Elevated serum 3-hydroxyisovaleric acid concentrations can be caused by supplementation with 3-hydroxyisovaleric acid, genetic conditions, or dietary deficiency of biotin. Some patients with isovaleric acidemia may benefit from supplemental biotin. Biotin deficiency on its own can have severe physiological and cognitive consequences that closely resemble symptoms of organic acidemias.
Treatment for all forms of this condition primarily relies on a low-protein diet, and depending on what variant of the disorder the individual suffers from, various dietary supplements. All variants respond to the levo isomer of carnitine as the improper breakdown of the affected substances results in sufferers developing a carnitine deficiency. The carnitine also assists in the removal of acyl-CoA, buildup of which is common in low-protein diets by converting it into acyl-carnitine which can be excreted in urine. Though not all forms of methylmalonyl acidemia are responsive to cobalamin, cyanocobalamin supplements are often used in first line treatment for this disorder. If the individual proves responsive to both cobalamin and carnitine supplements, then it may be possible for them to ingest substances that include small amounts of the problematic amino acids isoleucine, threonine, methionine, and valine without causing an attack.
A more extreme treatment includes kidney or liver transplant from a donor without the condition. The foreign organs will produce a functional version of the defective enzymes and digest the methylmalonic acid, however all of the disadvantages of organ transplantation are of course applicable in this situation. There is evidence to suggest that the central nervous system may metabolize methylmalonic-CoA in a system isolated from the rest of the body. If this is the case, transplantation may not reverse the neurological effects of methylmalonic acid previous to the transplant or prevent further damage to the brain by continued build up.
Patients with propionic acidemia should be started as early as possible on a low protein diet. In addition to a protein mixture that is devoid of methionine, threonine, valine, and isoleucine, the patient should also receive -carnitine treatment and should be given antibiotics 10 days per month in order to remove the intestinal propiogenic flora. The patient should have diet protocols prepared for him with a “well day diet” with low protein content, a “half emergency diet” containing half of the protein requirements, and an “emergency diet” with no protein content. These patients are under the risk of severe hyperammonemia during infections that can lead to comatose states.
Liver transplant is gaining a role in the management of these patients, with small series showing improved quality of life.
A diet with carefully controlled levels of the amino acids leucine, isoleucine, and valine must be maintained at all times in order to prevent neurological damage. Since these three amino acids occur in all natural protein, and most natural foods contain some protein, any food intake must be closely monitored, and day-to-day protein intake calculated on a cumulative basis, to ensure individual tolerance levels are not exceeded at any time. As the MSUD diet is so protein-restricted, and adequate protein is a requirement for all humans, tailored metabolic formula containing all the other essential amino acids, as well as any vitamins, minerals, omega-3 fatty acids and trace elements (which may be lacking due to the limited range of permissible foods), are an essential aspect of MSUD management. These complement the MSUD patient's natural food intake to meet normal nutritional requirements without causing harm. If adequate calories cannot be obtained from natural food without exceeding protein tolerance, specialised low protein products such as starch-based baking mixtures, imitation rice and pasta may be prescribed, often alongside a protein-free carbohydrate powder added to food and/or drink, and increased at times of metabolic stress. Some patients with MSUD may also improve with administration of high doses of thiamine, a cofactor of the enzyme that causes the condition.
Keeping MSUD under control requires careful monitoring of blood chemistry, both at home and in a hospital setting. DNPH or specialised dipsticks may be used to test the patient's urine for ketones (a sign of metabolic decompensation), when metabolic stress is likely or suspected. Fingerstick tests are performed regularly and sent to a laboratory to determine blood levels of leucine, isoleucine, and valine. Regular metabolic consultations, including blood-draws for full nutritional analysis, are recommended; especially during puberty and periods of rapid growth. MSUD management also involves a specially tailored metabolic formula, a modified diet, and lifestyle precautions such as avoiding fatigue and infections, as well as consuming regular, sufficient calories in proportion to physical stress and exertion. Without sufficient calories, catabolism of muscle protein will result in metabolic crisis. Those with MSUD must be hospitalised for intravenous infusion of sugars and nasogastric drip-feeding of formula, in the event of metabolic decompensation, or anorexia, diarrhea or vomiting. Food avoidance, rejection of formula and picky eating are all common problems with MSUD. Some patients may need to receive all or part of their daily nutrition through a feeding tube.
The primary treatment method for fatty-acid metabolism disorders is dietary modification. It is essential that the blood-glucose levels remain at adequate levels to prevent the body from moving fat to the liver for energy. This involves snacking on low-fat, high-carbohydrate nutrients every 2–6 hours. However, some adults and children can sleep for 8–10 hours through the night without snacking.
Carnitor - an L-carnitine supplement that has shown to improve the body's metabolism in individuals with low L-carnitine levels. It is only useful for Specific fatty-acid metabolism disease.
Dietary control may help limit progression of the neurological damage.
In terms of treatment for short-chain acyl-CoA dehydrogenase deficiency, some individuals may not need treatment, while others might follow administration of:
- Riboflavin
- Dextrose
- Anticonvulsants
Standard of care for treatment of CPT II deficiency commonly involves limitations on prolonged strenuous activity and the following dietary stipulations:
- The medium-chain fatty acid triheptanoin appears to be an effective therapy for adult-onset CPT II deficiency.
- Restriction of lipid intake
- Avoidance of fasting situations
- Dietary modifications including replacement of long-chain with medium-chain triglycerides supplemented with L-carnitine
Direct treatment that stimulates the pyruvate dehydrogenase complex (PDC), provides alternative fuels, and prevents acute worsening of the syndrome. However, some correction of acidosis does not reverse all the symptoms. CNS damage is common and limits a full recovery. Ketogenic diets, with high fat and low carbohydrate intake have been used to control or minimize lactic acidosis and anecdotal evidence shows successful control of the disease, slowing progress and often showing rapid improvement. No study has yet been published demonstrating the effectiveness of the ketogenic diet for treatment of PDCD.
There is some evidence that dichloroacetate reduces the inhibitory phosphorylation of pyruvate dehydrogenase complex and thereby activates any residual functioning complex. Resolution of lactic acidosis is observed in patients with E1 alpha enzyme subunit mutations that reduce enzyme stability. However, treatment with dichloroacetate does not improve neurological damage. Oral citrate is often used to treat acidosis.
Treatment or management of organic acidemias vary; eg see methylmalonic acidemia, propionic acidemia, isovaleric acidemia, and maple syrup urine disease.
As of 1984 there were no effective treatments for all of the conditions, though treatment for some included a limited protein/high carbohydrate diet, intravenous fluids, amino acid substitution, vitamin supplementation, carnitine, induced anabolism, and in some cases, tube-feeding.
As of 1993 ketothiolase deficiency and other OAs were managed by trying to restore biochemical and physiologic homeostasis; common therapies included restricting diet to avoid the precursor amino acids and use of compounds to either dispose of toxic metabolites or increase enzyme activity.
The conversion of tryptophan to serotonin and other metabolites depends on vitamin B. If tryptophan catabolism has any impact on brain glutaric acid and other catabolite levels, vitamin B levels should be routinely assayed and normalized in the course of the treatment of GA1.
Treatment centers on limiting intake of ammonia and increasing its excretion. Dietary protein, a metabolic source of ammonium, is restricted and caloric intake is provided by glucose and fat. Intravenous arginine (argininosuccinase deficiency) sodium phenylbutyrate and sodium benzoate (ornithine transcarbamoylase deficiency) are pharmacologic agents commonly used as adjunctive therapy to treat hyperammonemia in patients with urea cycle enzyme deficiencies. Sodium phenylbutyrate and sodium benzoate can serve as alternatives to urea for the excretion of waste nitrogen. Phenylbutyrate, which is the product of phenylacetate, conjugates with glutamine to form phenylacetylglutamine, which is excreted by the kidneys. Similarly, sodium benzoate reduces ammonia content in the blood by conjugating with glycine to form hippuric acid, which is rapidly excreted by the kidneys. A preparation containing sodium phenylacetate and sodium benzoate is available under the trade name Ammonul.
Acidification of the intestinal lumen using lactulose can decrease ammonia levels by protonating ammonia and trapping it in the stool. This is a treatment for hepatic encephalopathy.
Treatment of severe hyperammonemia (serum ammonia levels greater than 1000 μmol/L) should begin with hemodialysis if it is otherwise medically appropriate and tolerated.
Management for mitochondrial trifunctional protein deficiency entails the following:
- Avoiding factors that might precipitate condition
- Glucose
- Low fat/high carbohydrate nutrition
As with most other fatty acid oxidation disorders, individuals with MCADD need to avoid fasting for prolonged periods of time. During illnesses, they require careful management to stave off metabolic decompensation, which can result in death. Supplementation of simple carbohydrates or glucose during illness is key to prevent catabolism. The duration of fasting for individuals with MCADD varies with age, infants typically require frequent feedings or a slow release source of carbohydrates, such as uncooked cornstarch. Illnesses and other stresses can significantly reduce the fasting tolerance of affected individuals.
Individuals with MCADD should have an "emergency letter" that allows medical staff who are unfamiliar with the patient and the condition to administer correct treatment properly in the event of acute decompensation. This letter should outline the steps needed to intervene in a crisis and have contact information for specialists familiar with the individual's care.
Misdiagnosis issues
- The MCADD disorder is commonly mistaken for Reye Syndrome by pediatricians. Reye Syndrome is a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu.
- Most cases of Reye Syndrome are associated with the use of Aspirin during these viral infections.
Symptoms can be reduced through avoidance of leucine, an amino acid. Leucine is a component of most protein-rich foods; therefore, a low-protein diet is recommended. Some isolated cases of this disorder have responded to supplemental biotin; this is not altogether surprising, consider that other biotin-related genetic disorders (such as biotinidase deficiency and holocarboxylase synthetase deficiency) can be treated solely with biotin. Individuals with these multiple carboxylase disorders have the same problem with leucine catabolism as those with 3-methylcrotonyl-CoA carboxylase deficiency.
Since phytanic acid is not produced in the human body, individuals with Refsum disease are commonly placed on a phytanic acid-restricted diet and avoid the consumption of fats from ruminant animals and certain fish, such as tuna, cod, and haddock. Grass feeding animals and their milk are also avoided. Recent research has shown that CYP4 isoform enzymes could help reduce the over-accumulation of phytanic acid "in vivo". Plasmapheresis is another medical intervention used to treat patients. This involves the filtering of blood to ensure there is no accumulation of phytanic acid.
Treatment of LPI consists of protein-restricted diet and supplementation with oral citrulline. Citrulline is a neutral amino acid that improves the function of the urea cycle and allows sufficient protein intake without hyperammonemia. Under proper dietary control and supplementation, the majority of the LPI patients are able to have a nearly normal life. However, severe complications including pulmonary alveolar proteinosis and renal insufficiency may develop even with proper treatment.
Fertility appears to be normal in women, but mothers with LPI have an increased risk for complications during pregnancy and delivery.
Other therapeutic interventions include:
- ethosuximide and other anticonvulsant drugs
- GHB receptor antagonist NCS-382
- GABA receptor modulators
- uridine
- acamprosate
- dopaminergic agents
- dextromethorphan
- glutamine
- antioxidants
- Lamotrigine
The GABA(B) receptor antagonist, SGS-742, is currently being tested as a potential therapeutic in an NIH phase II clinical trial (NCT02019667).
The first suspicion of SPCD in a patient with a non-specific presentation is an extremely low plasma carnitine level. When combined with an increased concentration of carnitine in urine, the suspicion of SPCD can often be confirmed by either molecular testing or functional studies assessing the uptake of carnitine in cultured fibroblasts.
Identification of patients presymptomatically via newborn screening has allowed early intervention and treatment. Treatment for SPCD involves high dose carnitine supplementation, which must be continued for life. Individuals who are identified and treated at birth have very good outcomes, including the prevention of cardiomyopathy. Mothers who are identified after a positive newborn screen but are otherwise asymptomatic are typically offered carnitine supplementation as well. The long-term outcomes for asymptomatic adults with SPCD is not known, but the discovery of mothers with undiagnosed cardiomyopathy and SPCD has raised the possibility that identification and treatment may prevent adult onset manifestations.
Although there is currently no cure, treatment includes injections of structurally similar compound, N-Carbamoyl-L-glutamate, an analogue of N-Acetyl Glutamate. This analogue likewise activates CPS1. This treatment mitigates the intensity of the disorder.
If symptoms are detected early enough and the patient is injected with this compound, levels of severe mental retardation can be slightly lessened, but brain damage is irreversible.
Early symptoms include lethargy, vomiting, and deep coma.
The GABA antagonist CGP-35348 (3-amino-propyl-(diethoxymethyl) phosphinic acid) has been used in Aldh5a1-/- mice with strong results. It has shown to reduce the frequency of absence seizures, though there have been some cases in which it worsened convulsive seizures.
In ruminant animals, the gut fermentation of consumed plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats. Although humans cannot derive significant amounts of phytanic acid from the consumption of chlorophyll present in plant materials, it has been proposed that the great apes (bonobos, chimpanzees, gorillas, and orangutans) can derive significant amounts of phytanic acid from the hindgut fermentation of plant materials.