You have probably heard the word ammonia a few times. The term basically indicates the amount of ammonia found in the blood stream. The ammonia found in our body is a nitrogenous compound that is released following the deamination of amino acids (the building blocks of proteins) and the fermentation of some species of intestinal bacteria. What is ammonia and why is it found in the blood
Every activity that takes place inside the body tissues produces certain quantities of ammonia. However, food proteins, once processed, produce much higher amounts of ammonia. Consequently, a diet rich in proteins could temporarily lead to hyperammonaemia, while a diet that involves a reduced consumption of these elements could reduce the blood concentration. Deamination
During protein metabolism, we all know that the human body carries out a particular process called demination. In this phase, all amino acids are deprived of an amino group, known as NH2. What remains of this conversion is called alpha-keto acid. It is a compound that the human body uses to optimize energy levels. As for the NH2, however, the famous Krebs cycle comes into play, which gives rise to glutamate. As we will see later, this substance is essential for controlling ammonia levels in the blood because free ammonia (NH3) is produced from glutamate. Ammonia and intestines
In the intestine there is a particularly high production and metabolization activity due to the presence of specific species of intestinal bacteria. In fact, they are capable of degrading amino acids in urea. On the other hand, it is also present in the brain in the form of urea if it first passes through the liver. Finally, to make it harmless or inactivate it, you need glutamic acid. Hence the conversion of glutamic acid to glutamine plays a key role in maintaining the correct ammonia levels. Finally, the kidney eliminates ammonia through the urine when it is in the form of ammonium ion. Acid-base balance and ammonia
Part of the ammonia is also formed in the kidney, where the glutaminase enzyme is found, which transforms glutamine into glutamine acid and ammonia. When the latter becomes an ammonium ion it can finally be eliminated in the urine. This mechanism is essential for maintaining an excellent acid-base balance. Ammonia is dangerous for the nervous system
High amounts of ammonia in the human body are highly toxic to the nervous system and brain. For this reason, when everything is working properly, the liver turns it into urea. It is interesting to underline that a high-protein diet rarely causes pathological levels of ammonia – it is more likely that some ongoing pathologies do not allow its proper disposal.High levels of ammonia, the causes
As mentioned, a healthy organism is perfectly capable of managing high levels of ammonia, thanks to the liver which transforms ammonia into urea and allows its elimination through the urine. This means that high ammonia results – almost always – from severe liver failure. People with cirrhosis also generally have abnormal amounts of ammonia. In part it happens because the liver parenchyma, when in an altered state, can block the transport of blood that comes from the intestine. As a result, ammonia re-enters the bloodstream without having been purified through the liver. Why an ammonia test is required
Doctors usually order this type of test to assess how well the liver is functioning in the presence of severe liver disease such as cirrhosis. It can also be requested if a specialist finds altered states of consciousness, coma of unknown origin, hepatic encephalopathy, problems in the metabolism of the urea cycle. Causes of high ammonia
- Metabolic alkalosis
- Taking medications
- Cirrhosis of the liver
- Hyperprotein diets
- Defects of enzymes involved in the urea cycle
- Dysbiosis
- Epatiti gravi
- Intense physical exercise
- Heart failure
- Hepatic insufficiency
- Asparagine poisoning
- Acute leukemia
- Hemolytic disease of the newborn
- Gastrointestinal obstruction
- Bleeding from the stomach or intestines
- Reye’s syndrome
Ammonemia, normal
values ​​Reference values ​​(which may vary depending on the laboratory) are between 21 – 50 µmol / l. Some structures calculate it, however, differently: 15 – 60 µcg / 100ml. While other workshops differentiate the values ​​between men, women and children:
- Donna: 10-80 mcg / dL
- Man: 10-100 mcg / dL
- Child: 40-80 mcg / dL
- Neonato: 90-150 mcg / dL
- Cerebrospinal fluid ammonia (CSF) level: 10-35 mg / dL (5.87-20.5 mmol / L)
Medicines that can cause high ammonia
- Acetazolamide
- Ethacrynic acid
- Valproic acid
- Chlorthalidone
- Furosemide​​​​​​​
- Isoniazide​​​​​​​
- Potassium salts
Symptoms encountered in patients with high ammonia
Not all patients exhibit typical symptoms and not necessarily a severity of symptoms related to the amount of ammonia in the blood. Many people begin by refusing meat and other protein foods and may have several episodes of vomiting (related to liver malfunction). In some cases, however, the signs of high ammonia can be much more severe with lethargy, mental retardation, disorientation and coma. If you do not act quickly, an individual can lead to death. Low ammonia
More rarely, some people suffer from low ammonia. Generally they are people who follow a low-protein diet or who take particular types of drugs such as Levodopa, Neomycin, Kanamycin and Lactulose. According to some theories, even lactobacillus would reduce ammonia. Even hypertension, hyperornithinemia and hypothyroidism (albeit very rarely) could reduce the levels. How the ammonia test is carried out
To monitor the levels of ammonia, a simple vein must be done. Fasting is not always necessary, however it is important to avoid eating high-protein foods in the previous 24 hours. Levels can also be affected by strenuous physical activity or cigarette smoking. Therefore it would be advisable to abstain before the exam. Situations that could affect the data collected by the laboratory:
- Severe bleeding
- Intense muscle activity
- Tourniquet too tight when collecting blood sample
- Hemolysis
- Cigarette smoke
- Cannabis intake
- Delays in transport to the laboratory after collection or before the completion of the analysis
Fonti scientifiche
[1] Ammonia – MedScape
[2] World J Gastroenterol. 2017 Jul 28; 23(28): 5246–5252. Published online 2017 Jul 28. doi: [10.3748/wjg.v23.i28.5246] PMCID: PMC5537191 PMID: 28811719 Refractory hepatic encephalopathy in a patient with hypothyroidism: Another element in ammonia metabolism Fernando Diaz-Fontenla, Marta Castillo-Pradillo, Arantxa Diaz-Gomez, Luis Ibanez-Samaniego, Pilar Gancedo, Juan Adan Guzman-de-Villoria, Pilar Fernandez-Garcia, Rafael Banares-Canizares, and Rita Garcia-Martinez
[3] Ammonia-induced energy disorders interfere with bilirubin metabolism in hepatocytes. Arch Biochem Biophys. 2014; 555-556:16-22 (ISSN: 1096-0384) Wang Q; Wang Y; Yu Z; Li D; Jia B; Li J; Guan K; Zhou Y; Chen Y; Kan Q
​​​​​​​[4] Science. Author manuscript; available in PMC 2018 Jan 2. Published in final edited form as: Science. 2017 Nov 17; 358(6365): 941–946. Published online 2017 Oct 12. doi: [10.1126/science.aam9305] PMCID: PMC5748897 NIHMSID: NIHMS924606 PMID: 29025995 Metabolic recycling of ammonia via glutamate dehydrogenase supports breast cancer biomass Jessica B. Spinelli,1,2 Haejin Yoon,1 Alison E. Ringel,1 Sarah Jeanfavre,2 Clary B. Clish,2 and Marcia C. Haigis1,
