AST/ALT ratio

The AST/ALT ratio is the ratio between the concentrations of the enzymes aspartate transaminase (AST) and alanine transaminase, aka alanine aminotransferase (ALT) in the blood of a human or animal. It is measured with a blood test and is sometimes useful in medical diagnosis to differentiate between causes of liver damage, or hepatotoxicity.[1][2][3]

AST/ALT ratio
Medical diagnostics
LOINC16325-3, 1916-6

Most causes of liver cell injury are associated with a greater increase in ALT than AST; however, an AST to ALT ratio of 2:1 or greater is suggestive of alcoholic liver disease, particularly in the setting of an elevated gamma-glutamyl transferase.[4]

The AST to ALT ratio can also occasionally be elevated in a liver disease pattern in patients with nonalcoholic steatohepatitis, and it is frequently elevated in an alcoholic liver disease pattern in patients with hepatitis C who have developed cirrhosis. In addition, patients with Wilson's disease or cirrhosis due to viral hepatitis may have an AST that is greater than the ALT, though the ratio typically is not greater than two.

When the AST is higher than ALT, a muscle source of these enzymes should be considered. For example, muscle inflammation due to dermatomyositis may cause AST>ALT. This is a good reminder that AST and ALT are not good measures of liver function when other sources may increase AST or ALT, because they do not reliably reflect the synthetic ability of the liver, and they may come from tissues other than liver (such as muscle).

Magnitude of AST and ALT elevations

The magnitude of AST and ALT elevations vary depending on the cause of the hepatocellular injury [16-19]. While values may vary between individuals, the following are typical AST and ALT patterns relating to the "upper limit of normal" (ULN):[5][6][7][8]

  • Alcoholic fatty liver disease: AST > 8 times the ULN; ALT > 5 times the ULN
  • Nonalcoholic fatty liver disease: AST and ALT > 4 times the ULN
  • Acute viral hepatitis or toxin-related hepatitis with jaundice: AST and ALT > 25 times the ULN
  • Ischemic hepatopathy (ischemic hepatitis, shock liver): AST and ALT > 50 times the ULN (in addition the lactate dehydrogenase is often markedly elevated)
  • Chronic hepatitis C virus infection: Wide variability, typically normal to less than twice the ULN, rarely more than 10 times the ULN
  • Chronic hepatitis B virus infection: Levels fluctuate; the AST and ALT may be normal, though most patients have mild to moderate elevations (approximately twice the ULN); with exacerbations, levels are more than 10 times the ULN

History
Pathophysiology sample values
BMP/ELECTROLYTES:
Na+ = 140 Cl− = 100 BUN = 20 /
Glu = 150
K+ = 4 CO2 = 22 PCr = 1.0 \
ARTERIAL BLOOD GAS:
HCO3− = 24 paCO2 = 40 paO2 = 95 pH = 7.40
ALVEOLAR GAS:
pACO2 = 36 pAO2 = 105 A-a g = 10
OTHER:
Ca = 9.5 Mg2+ = 2.0 PO4 = 1
CK = 55 BE = −0.36 AG = 16
SERUM OSMOLARITY/RENAL:
PMO = 300 PCO = 295 POG = 5 BUN:Cr = 20
URINALYSIS:
UNa+ = 80 UCl− = 100 UAG = 5 FENa = 0.95
UK+ = 25 USG = 1.01 UCr = 60 UO = 800
PROTEIN/GI/LIVER FUNCTION TESTS:
LDH = 100 TP = 7.6 AST = 25 TBIL = 0.7
ALP = 71 Alb = 4.0 ALT = 40 BC = 0.5
AST/ALT = 0.6 BU = 0.2
AF alb = 3.0 SAAG = 1.0 SOG = 60
CSF:
CSF alb = 30 CSF glu = 60 CSF/S alb = 7.5 CSF/S glu = 0.4

It is also known as the "De Ritis Ratio",[9][10] named after Fernando De Ritis, who performed analysis on transaminases in 1957.[10]

See also

References
  1. Nyblom H, Berggren U, Balldin J, Olsson R (2004). "High AST/ALT ratio may indicate advanced alcoholic liver disease rather than heavy drinking". Alcohol Alcohol. 39 (4): 336–9. doi:10.1093/alcalc/agh074. PMID 15208167.
  2. Nyblom H, Björnsson E, Simrén M, Aldenborg F, Almer S, Olsson R (September 2006). "The AST/ALT ratio as an indicator of cirrhosis in patients with PBC". Liver Int. 26 (7): 840–5. doi:10.1111/j.1478-3231.2006.01304.x. PMID 16911467.
  3. Gopal DV, Rosen HR (February 2000). "Abnormal findings on liver function tests. Interpreting results to narrow the diagnosis and establish a prognosis". Postgrad Med. 107 (2): 100–2, 105–9, 113–4. doi:10.3810/pgm.2000.02.869. PMID 10689411.
  4. Moussavian, S. N.; Becker, R. C.; Piepmeyer, J. L.; Mezey, E.; Bozian, R. C. (Mar 1985). "Serum gamma-glutamyl transpeptidase and chronic alcoholism. Influence of alcohol ingestion and liver disease". Dig Dis Sci. 30 (3): 211–4. doi:10.1007/bf01347885. PMID 2857631.
  5. Gitlin, N.; Serio, K. M. (Jul 1992). "Ischemic hepatitis: widening horizons". Am J Gastroenterol. 87 (7): 831–6. PMID 1615936.
  6. Fuchs, S.; Bogomolski-Yahalom, V.; Paltiel, O.; Ackerman, Z. (Apr 1998). "Ischemic hepatitis: clinical and laboratory observations of 34 patients". J Clin Gastroenterol. 26 (3): 183–6. doi:10.1097/00004836-199804000-00007. PMID 9600366.
  7. Henrion, J.; Schapira, M.; Luwaert, R.; Colin, L.; Delannoy, A.; Heller, F. R. (Nov 2003). "Hypoxic hepatitis: clinical and hemodynamic study in 142 consecutive cases". Medicine (Baltimore). 82 (6): 392–406. doi:10.1097/01.md.0000101573.54295.bd. PMID 14663289.
  8. Lok AS, McMahon BJ (February 2007). "Chronic hepatitis B". Hepatology. 45 (2): 507–39. doi:10.1002/hep.21513. hdl:2027.42/55941. PMID 17256718.
  9. Kenneth D. McClatchey (2002). Clinical laboratory medicine. Lippincott Williams & Wilkins. pp. 288–. ISBN 978-0-683-30751-1. Retrieved 21 May 2010.
  10. De Ritis F, Coltorti M, Giusti G (July 2006). "An enzymic test for the diagnosis of viral hepatitis: the transaminase serum activities. 1957". Clin. Chim. Acta. 369 (2): 148–52. doi:10.1016/j.cca.2006.05.001. PMID 16781697.
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