Alanine Aminotransferase (ALT)

What Is ALT?

Alanine aminotransferase (ALT) is an enzyme which is mostly found in the liver. Significant amounts of ALT can be found in the kidneys, muscles and the heart while smaller amounts are found in the pancreas, lungs and spleen.[1]

Which tests include this marker?

What Role Does it play In The Body?

ALT is used as a clinical biomarker for liver or hepatic health and plays an important role in the alanine cycle.

During exercise, the skeletal muscles – those attached to bone – break down and nitrogen and carbon are released as a result. As part of the alanine cycle, ALT transports the nitrogen and carbon released from skeletal muscles to the liver in the form of alanine. ALT catalyses the transfer of an amino group from alanine to alpha-ketoglutarate to form pyruvate in the liver, which is used to generate glucose for energy. Therefore, ALT has key roles in gluconeogenesis as well as the formation of urea. Gluconeogenesis is a pathway which occurs in the liver and kidneys to make sugar (glucose) from non-carbohydrate substances and is used for energy. The process usually occurs when dietary intake of glucose is low or not happening at all.

As ALT is so abundant in the liver, it is a good indicator of hepatic or liver injury. For example, if the liver cells are damaged or injured, ALT leaks out into the bloodstream. This damage can be a result of infections such as hepatitis or drug/alcohol excesses or overdose. However, leakage of ALT into the bloodstream is not necessarily exclusive to the liver and can occur because of injury to skeletal or cardiac muscle. Certain drugs can also increase the expression of ALT. [2]

Individuals with increased levels of aminotransferases such as ALT are at a higher risk of non-alcoholic fatty liver disease, type 2 diabetes mellitus as well as cardiovascular disease.[3]

How Does ALT Affect My Wellbeing?

Individuals who lead a sedentary lifestyle can be at a greater risk of depression, anxiety as well as weight gain and low energy. People who have high ALT levels may be at risk of being overweight, obese or developing an illness which in turn can have a negative effect on their mood.

Liver injury or disease such as hepatitis can also affect your general wellbeing. Hepatitis can present itself as flu-like symptoms and generally make you feel unwell.

How Can I Improve My Result?

Increased ALT can be an indicator of fatty liver disease which can develop in concurrence with obesity. Therefore, it is important to maintain healthy lifestyle choices to keep your ALT levels within normal parameters.

Lower levels of ALT can be an indicator of frailty in middle aged-elderly populations. Less is known about the clinical implications of decreased ALT levels.


Food can have a major effect on our blood ALT levels. A diet high in dietary fibre such as fruit and vegetables can help to improve ALT activity. [4]

Alcohol may also impact blood ALT levels. The effect of alcohol consumption on liver enzyme activity including ALT increases as your body mass index (BMI) increases. [5] Therefore, it is recommended that you keep alcohol consumption within the guidelines – no more than 14 units per week. [6]


Obesity is a major risk factor for the development of liver injury as well as other illnesses and disorders.

Increased participation in physical activity, as well as weight loss, has been shown to improve serum ALT levels. [7] You should aim for around 150 minutes of aerobic physical activity per week such as swimming, walking or cycling. However, you should consult your GP before beginning any new training or exercise regime.

Tests that include this marker

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[1] Washington, I, M and Van Hoosier, G. (2012). Clinical Biochemistry and Hematology. In: Suckow, M, A., Stevens, K, A and Wilson, R, P ed. The Laboratory Rabbit, Guinea Pig, Hamster and Other Rodents. Elsevier, pp 57 – 60.

[2] Gwaltney-Brant, S, M. (2016). Nutraceuticals in Hepatic Diseases. In: Gupta, R, C ed. Nutraceuticals Efficacy, Safety and Toxicity. Elsevier, pp 87-99.

[3] Portillo-Sanchez, P., Bril, F., Maximos, M., Lomonaco, R., Biernacki, D., Orsak, B., Subbarayan, S., Webb, A., Hecht, J., Cusi, K. (2015). High Prevalence of Nonalcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Mellitus and Normal Plasma Aminotransferases Levels. The Journal od Clinical Endocrinology and Metabolism: 100 (6), pp 2231-2238.

[4] Iwamoto, M., Yagi, K and Sato, M. (2013). Eating a Healthy Lunch Improves Serum Alanine Aminotransferase Activity. Lipids Health Dis: 12.

[5] Alatalo, P, I., Kivisto, H, M., Hietala, J, P., Puukka, K, S., Bloigu, R and Niemelä, O, J. (2008). Effect of Moderate Alcohol Consumption on Liver Enzymes Increases with Increasing Body Mass Index. The American Journal of Clinical Nutrition: 88(4), pp 1097-1103.

[6] National Health Service. (2018).  Alcohol Units. Available at:

[7] Hickman, I, J., Jonsson, J, R., Prins, J, B., Ash, S., Purdie, D, M., Clouston, A, D and Powell, E, E. (2003). Modest Weight Loss and Physical Activity in Overweight Patients with Chronic Liver Disease Results in Sustained Improvements in Alanine Aminotransferase, Fasting Insulin, and Quality of Life. Gut: 53, pp 413-419.

[8] Ramaty, E., Maor, E., Peltz-Sinvani, N., Brom, A., Grinfield, A., Kivity, S., Segev, S., Sidi, Y., Kessler, T., Sela, B, A and Segal, G. (2014). Low ALT Blood Levels Predict Long-Term All-Cause Mortality Among Adults. A Historical Prospective Cohort Study. European Journal of Internal Medicine: 25 (10), pp 919-921.

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