"LFTs" redirects here. For other uses, see LFT.
Liver function tests | |
---|---|
Intervention | |
Liver Function and its markers raised in different conditions | |
ICD-10-PCS | K-70 to K-77 |
ICD-9-CM | 570-573 |
MeSH | D008111 |
Liver function tests (LFTs or LFs), are groups of clinical biochemistry laboratory blood assays designed to give information about the state of a patient's liver.[1] The parameters measured include PT/INR, aPTT, albumin, billirubin (direct and indirect) and others. According to some, liver transaminases (AST/ALT (SGOT/SGPT) are not liver function tests, but are biomarkers of liver injury in a patient with some degree of intact liver function.[citation needed] Other sources include transaminases.[2][3] Most liver diseases cause only mild symptoms initially, but it is vital that these diseases be detected early. Hepatic (liver) involvement in some diseases can be of crucial importance. This testing is performed by a medical technologist on a patient's serum or plasma sample obtained by phlebotomy. Some tests are associated with functionality (e.g., albumin); some with cellular integrity (e.g., transaminase) and some with conditions linked to the biliary tract (gamma-glutamyl transferase and alkaline phosphatase). Several biochemical tests are useful in the evaluation and management of patients with hepatic dysfunction. These tests can be used to (1) detect the presence of liver disease, (2) distinguish among different types of liver disorders, (3) gauge the extent of known liver damage, and (4) follow the response to treatment. Some or all of these measurements are also carried out (usually about twice a year for routine cases) on those individuals taking certain medications- anticonvulsants are a notable example- in order to ensure that the medications are not damaging the person's liver.
Contents
[hide]- 1 Standard liver panel
- 2 Other tests commonly requested alongside LFTs
- 3 See also
- 4 References
- 5 External links
[edit] Standard liver panel
Albumin (Alb)
Reference range |
3.5 to 5.3 g/dL |
[edit] Alanine transaminase (ALT)
Reference range |
9 to 52 IU/L[4] |
[edit] Aspartate transaminase (AST)
Reference range |
10 to 35 IU/L[4] |
[edit] Alkaline phosphatase (ALP)
Reference range |
30 to 120 IU/L[4] |
[edit] Total bilirubin (TBIL)
Reference range |
0.2–1.2 mg/dL |
Increased total bilirubin causes jaundice, and can signal a number of problems:
- 1. Prehepatic: Increased bilirubin production. This can be due to a number of causes, including hemolytic anemias and internal hemorrhage.
- 2. Hepatic: Problems with the liver, which are reflected as deficiencies in bilirubin metabolism (e.g., reduced hepatocyte uptake, impaired conjugation of bilirubin, and reduced hepatocyte secretion of bilirubin). Some examples would be cirrhosis and viral hepatitis.
- 3. Posthepatic: Obstruction of the bile ducts, reflected as deficiencies in bilirubin excretion. (Obstruction can be located either within the liver or in the bile duct).
[edit] Direct bilirubin (Conjugated Bilirubin)
Reference range |
0.1–0.4 mg/dL |
- If direct (i.e. conjugated) bilirubin is normal, then the problem is an excess of unconjugated bilirubin, and the location of the problem is upstream of bilirubin excretion. Hemolysis, viral hepatitis, or cirrhosis can be suspected.
- If direct bilirubin is elevated, then the liver is conjugating bilirubin normally, but is not able to excrete it. Bile duct obstruction by gallstones or cancer should be suspected.
[edit] Gamma glutamyl transpeptidase (GGT)
Reference range |
0 to 42 IU/L[4] |
[edit] Other tests commonly requested alongside LFTs
5' Nucleotidase (5'NTD)
5' Nucleotidase is another test specific for cholestasis or damage to the intra or extrahepatic biliary system, and in some laboratories, is used as a substitute for GGT for ascertaining whether an elevated ALP is of biliary or extra-biliary origin.
[edit] Coagulation test (e.g., INR)
The liver is responsible for the production of coagulation factors. The international normalized ratio (INR) measures the speed of a particular pathway of coagulation, comparing it to normal. Increased levels of INR means that blood is taking more time than usual to coagulate or clot. The INR will be increased only if the liver is so damaged that synthesis of vitamin K-dependent coagulation factors has been impaired; it is not a sensitive measure of liver function.It is very important to normalize the INR before operating on people with liver problems (usually by transfusion with blood plasma containing the deficient factors) as they could bleed excessively.
[edit] Serum glucose (BG, Glu)
The liver's ability to produce glucose (gluconeogenesis) is usually the last function to be lost in the setting of fulminant liver failure.[edit] Lactate dehydrogenase (LDH)
Lactate dehydrogenase is an enzyme found in many body tissues, including the liver. Elevated levels of LDH may indicate liver damage.[edit] See also
- Reference ranges for blood tests
- Elevated transaminases
- Liver disorders and liver diseases.
[edit] References
- ^ Lee, Mary (2009-03-10). Basic Skills in Interpreting Laboratory Data. ASHP. pp. 259–. ISBN 9781585281800. http://books.google.com/books?id=AUSIRcV_as0C&pg=PA259. Retrieved 5 August 2011.
- ^ McClatchey, Kenneth D. (2002). Clinical laboratory medicine. Lippincott Williams & Wilkins. pp. 288–. ISBN 9780683307511. http://books.google.com/books?id=3PJVLH1NmQAC&pg=PA288. Retrieved 5 August 2011.
- ^ Mengel, Mark B.; Schwiebert, L. Peter (2005). Family medicine: ambulatory care & prevention. McGraw-Hill Professional. pp. 268–. ISBN 9780071423229. http://books.google.com/books?id=XvLo7xvmFo0C&pg=PA268. Retrieved 5 August 2011.
- ^ a b c d[broken citation]
- ^ 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): 336–339. doi:10.1093/alcalc/agh074. PMID 15208167. http://alcalc.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=15208167.
- ^ 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): 840–845. doi:10.1111/j.1478-3231.2006.01304.x. PMID 16911467. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1478-3223&date=2006&volume=26&issue=7&spage=840.
[edit] External links
- MeSH Liver+function+tests
- Overview at Mayo Clinic
- Abnormal Liver Function Tests
- Overview of liver enzymes
http://en.wikipedia.org/wiki/Liver_function_tests#Albumin_.28Alb.29