Hyperammonaemia

Classification according to ICD-10
E72.2	Urea cycle disorders hyperammonaemia
ICD-10 online (WHO version 2019)

Under hyperammonemia is meant an abnormally increased ammonium content in the blood . This is usually due to a congenital enzyme defect in the urea cycle . The defective enzymes cannot break down ammonia, so it accumulates in the blood. If left untreated, hyperammonaemia results in brain damage and disability.

causes

Enzyme defects in the urea cycle

The enzyme defect is inherited and has a frequency of 1 / 8,200 newborns. The ornithine transcarbamylase deficiency is inherited in an X-linked recessive manner. The five other enzyme defects are inherited as an autosomal recessive trait.

• Ornithine transcarbamylase (most common defect), also ornithine keto acid transaminase
• Carbamoyl Phosphate Synthetase I.
• Argininosuccinate synthase
• Argininosuccinate lyase
• N- acetyl glutamate synthetase (NAGS)
• Arginase 1

See also main article urea cycle defects .

Other causes

Also Organic Azidurien and fatty acid oxidation defects can lead to hyperammonemia.

Another cause of hyperammonaemia can be a zinc deficiency, which is easy to moderate and rarely difficult to find around the world.

Symptoms

The symptoms differ depending on the age when they first appeared (manifestation):

• Manifestation in newborns: life-threatening course with poor drinking, lethargy , hypotension
• Manifestation in infancy: less acute course with failure to thrive and lethargy
• Manifestation in early childhood or puberty : episode-like crises with vomiting , headache , learning problems, mental retardation , ataxia

treatment

Regardless of the exact cause of the hyperammonaemia, the level of ammonia in the blood must be lowered immediately. The following measures are carried out for this purpose:

• immediate stop of all protein intake
• Sugar infusion and insulin administration
• Arginine administration
• drug detoxification via the kidneys with benzoate , phenyl acetate or phenylbutyrate (form conjugates with glycine or glutamine)
• Carnitine
• Diuresis
• if necessary dialysis
• Oral intake of lactulose (is broken down by intestinal bacteria into acidic lactate and acetone , among other things ; the intestinal environment becomes more acidic, ammonia is protonated into ammonium , which is not absorbed by the intestine)

Hyperammonaemia due to N-acetylglutamate synthetase deficiency can be effectively treated with carglumic acid . In the further course a diet is necessary.

forecast

The earlier the disease is recognized and treated, the less brain damage will occur.

Hyperammonaemia, whether caused by a lack of zinc or otherwise, can, in conjunction with sickle cell anemia, lead to encephalopathy .

Individual evidence

1. ↑ LM Plum, L. Rink, H. Haase: The essential toxin: impact of zinc on human health. In: International journal of environmental research and public health. Volume 7, number 4, April 2010, pp. 1342-1365, doi: 10.3390 / ijerph7041342 , PMID 20617034 , PMC 2872358 (free full text) (review).
2. ↑ M. Dardenne, W. Savino, S. Wade, D. Kaiserlian, D. Lemonnier, JF Bach: In vivo and in vitro studies of thymulin in marginally zinc-deficient mice. In: European Journal of Immunology. Volume 14, Number 5, May 1984, pp. 454-458, doi: 10.1002 / eji.1830140513 , PMID 6609827 .
3. ↑ http://www.who.int/whr/2002/chapter4/en/index3.html
4. ↑ H. Lüllmann, K. Mohr, L. Hein: Pharmakologie und Toxikologie , 17th edition, Georg Thieme Verlag, Stuttgart 2010, ISBN 978-3-13-151647-3 , p. 267.
5. ↑ GM Enns et al .: Survival after treatment with phenylacetate and benzoate for urea-cycle disorders . In: N Engl J Med . No. 356 , 2007, p. 2282-2292 ( abstract ).
6. ↑ http://journal.publications.chestnet.org/article.aspx?articleid=1095755

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !