LiMAx test

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The LiMAx test (maximum liver function capacity) is a dynamic liver function test that is based on the metabolism of 13 C-methacetin by the liver-specific cytochrome P450-1A2 system and reflects the current liver performance at the moment of measurement at the patient's bedside ( point-of -Care-Testing ).

Test principle

The LiMAx test is an innovative and liver-specific C13 breath test . As part of this, 13 C-methacetin is administered intravenously to the patient and reaches the liver with the bloodstream. Here 13 C-methacetin is metabolized by the cytochrome P450 1A2 to paracetamol and ultimately to 13 CO 2 , which is then transported via the bloodstream to the lungs and exhaled here.

Methacetin is metabolized by the liver-specific cytochrome P450 1A2 to paracetamol and 13 C-formaldehyde, which is then converted into 13 CO 2 in several steps .

Cytochrome P450 1A2 is evenly distributed over all cells of a liver acinar and, in contrast to other members of the cytochrome P450 family, occurs exclusively in the liver. Furthermore, the cytochrome P450 1A2 mentioned can hardly be induced by drugs that are frequently used in clinical practice. The 13 C-methacetin used as test substance is non-toxic in the dosage used and very well tolerated. The 13 C used for labeling is also a stable, naturally occurring and non-radioactive carbon isotope . For this reason, patients must fast for at least three hours before the measurement in order to rule out possible interference with carbon from the diet.

Test execution

At the beginning of the test, the patient is put on a breathing mask that separates the inhaled air from the exhaled air through two valves. The individual ratio is then as part of a baseline measurement 13 CO 2 / 12 CO 2 in the exhaled air over a period of 10 to 20 minutes determined (Fig.).

Through continuous measurement of the 13 CO 2 / 12 CO 2 -Ratio can after injection and metabolism of 13 are determined C-methacetin individual liver function.

After injection of 13 C-methacetin increases the ratio of 13 CO 2 / 12 CO 2 accordingly and continuously quantified by special laser technique on the patient bed (FLIP). Always Since only the ratio of the measurement during the 13 CO 2 / 12 CO 2 is measured, chronic lung diseases affect (z. B. COPD , fibrosis not) the result. The conversion of 13 C-methacetin over time can then be determined by means of kinetic analysis . The LiMAx is the result of the maximum value of the substrate turnover normalized to the body weight.

Clinical application

The LiMAx has so far been widely used in German, Austrian and Swiss university hospitals for hepatological and liver surgery issues. Stockmann et al. was able to show that the LiMAx is an excellent predictor for postoperative liver failure after liver surgery. According to Lock et al. the onset of liver regeneration can also be well characterized. In the context of a liver transplant , the LiMAx test can be used to identify dysfunctions or non-function of the transplant promptly after transplantation and patients can benefit from appropriate clinical management. Existing cirrhosis of the organ can also be adequately diagnosed with the aid of the LiMAx test and graded according to functional impairment. Current research on the LiMAx test is concerned with a. with the non-invasive diagnosis of liver cirrhosis, the influence of chemotherapy on liver function and liver function-dependent drug therapy as well as other hepatological and liver surgery issues.

Web links

Individual evidence

  1. ↑ CN Palmer, PJ Coates, SE Davies et al .: Localization of cytochrome P-450 gene expression in normal and diseased human liver by in situ hybridization of wax-embedded archival material . In: Hepatology , 1992, 16 (3), pp. 682-687
  2. ↑ GA Starmer, S. McLean, J. Thomas: Analgesic potency and acute toxicity of substituted anilides and benzamides . In: Toxicology and applied pharmacology , 1971, 19 (1), pp. 20-28
  3. ↑ FLIP ( Memento of the original from March 6, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.humedics.de
  4. ↑ M. Jara, J. Bednarsch, JF Lock et al .: [Enhancing safety in liver surgery using a new diagnostic tool for evaluation of actual liver function capacity - The LiMAx test]. In: Deutsche Medizinische Wochenschrift , 2014, 139 (8), pp. 387-391
  5. ↑ M. Stockmann, JF Lock, B. Riecke et al .: Prediction of postoperative outcome after hepatectomy with a new bedside test for maximal liver function capacity . In: Annals of Surgery , 2009, 250 (1), pp. 119-125
  6. ↑ M. Stockmann, JF Lock, M. Malinowski et al .: The LiMAx test: a new liver function test for predicting postoperative outcome in liver surgery . In: HPB , 2010, 12 (2), pp. 139-146
  7. ↑ JF Lock, M. Malinowski, D. Seehofer et al .: Function and volume recovery after partial hepatectomy: influence of preoperative liver function, residual liver volume, and obesity . In: Langenbeck's archives of surgery , 2012
  8. ↑ JF Lock, FE Schwabauer, P. Martus et al .: Early diagnosis of primary nonfunction and indication for reoperation after liver transplantation . In: Liver transplantation , 2010, 16 (2), pp. 172-180
  9. ↑ M. Stockmann, JF Lock, M. Malinowski et al .: Accurate Diagnosis and Grading of Cirrhosis using the new LiMAx test . In: Journal of hepatology , 2012, 56, pp. 389-548
  10. ↑ Current research on the LiMAx test