R-value for Liver Injury Online calculator | ClinCaseQuest (2024)

Nataliia Lopina January 19, 2022

R-value for Liver Injury Online calculator | ClinCaseQuest (2)

Can be used in patients with suspected drug induced liver injury (DILI) with abnormal liver chemistries.

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R-value= (patient’s ALT / upper limit of normal ALT ) / ( patient’s ALP / upper limit of normal ALP )

Note: Normal values may vary by lab.

  • R-value calculation allows clinicians to collectively identify and describe the pattern of liver injury in an objective manner.
  • R-value calculation allows clinicians suspecting a diagnosis of DILI to formulate an organized diagnostic strategy to rule out other causes of acute liver injury and to narrow the list of possible culprit drugs based on the pattern of liver injury.
  • Recommended by guidelines.

Parameters that required for the assessment:

  • Patient’s ALT, U/L
  • Upper limit of normal ALT According to your lab, U/L
  • Patient’s ALP, U/L
  • Upper limit of normal ALP According to your lab, U/L

Interpretation:

R-value rangeThe type of the liver injury Conclusion and Advise
<2 Cholestatic pattern of liver injury. • Pancreatic malignancy, cholangiocarcinoma, primary malignancy of the gallbladder, choledocholithiasis, sepsis, TPN, heart failure, PSC, and PBC should be ruled out as causes
• Commonly used drugs that can cause this pattern of liver injury include: amoxicillin/clavulanate, trimethoprim/sulfamethoxazole, azathioprine, and anabolic steroids
• Recommend imaging studies (e.g. abdominal ultrasound)
2-5Mixed pattern of liver injury. Recommend acute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound)
>5Hepatocellular pattern of liver injury. • Acute viral hepatitis, ischemic liver injury, Budd-Chiari syndrome, autoimmune hepatitis, and Wilson’s disease (in younger patients) should be ruled out as causes
• Commonly used drugs that can cause this pattern of liver injury include: isoniazid, macrolides, nitrofurantoin, minocycline, anti-epileptics, NSAIDs, green tea extract, and inhaled anesthetics
• Recommend acute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound)

Futher diagnostic approach:

R FactorInjury typeRecommended 1st line tests*
>5HepatocellularAcute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound)
2–5MixedAcute viral hepatitis serologies, HCV RNA and autoimmune hepatitis serologies, imaging studies (e.g. abdominal ultrasound)
<2CholestaticImaging studies (e.g. abdominal ultrasound)

*FromChalasani 2014

The R-value (also known as the R ratio or R factor) was introduced after an international consensus meeting in 1989 aimed at preparing definitions and criteria related to drug related liver injury. At the request of the Council for International Organizations of Medical Sciences (CIOMS), a pilot program led by pharmaceutical company Roussel Uclaf was initiated to help classify different patterns of acute liver injury, introducing the R-value.

The R-value itself has not been validated, but remains commonly used in clinical practice to objectively define different patterns of liver injury. The American College of Gastroenterology (ACG) has incorporated the R-value in itsguidelinesfor diagnosis and management of idiosyncratic drug-induced liver injury.

Recommendations for workup based on R Factor, adapted fromChalasani 2014

  • The pattern of acute liver injury (and therefore the R-value) can vary throughout the clinical course of the illness.
  • Identifying the pattern of liver injury can guide diagnostic approach to DILI, including appropriate further diagnostic testing necessary to rule out other causes of liver injury.
  • Calculating the R-value is the first step in calculating theRoussel Uclaf Causality Assessment Method (RUCAM)when determining if liver injury is related to a specific drug.
  • Because the pattern of liver injury can evolve over time, the time point at which liver chemistries are used to calculate the R-value can alter the final result. It is recommended that the initial liver chemistries suggesting liver injury be used, but ultimately left to the clinician to decide what set of liver chemistries to use when making an assessment.
  • The use of upper limit of normal (ULN) in the equation creates some room for variability. The ULN varies among different laboratories.
  • While not validated, the R-value is widely used and has been incorporated intoguideline recommendationsfor assessing liver injury.
  • Though the R Factor does not incorporate coagulopathy (INR) and mental status, these two factors should always be immediately assessed in all cases of acute liver injury to rule out acute liverfailure.

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Literature

  1. Bénichou C. Criteria of drug-induced liver disorders. Report of an international consensus meeting. J Hepatol. 1990 Sep;11(2):272-6. doi: 10.1016/0168-8278(90)90124-a. PMID: 2254635.
  2. Chalasani NP, Hayashi PH, Bonkovsky HL, Navarro VJ, Lee WM, Fontana RJ; Practice Parameters Committee of the American College of Gastroenterology. ACG Clinical Guideline: the diagnosis and management of idiosyncratic drug-induced liver injury. Am J Gastroenterol. 2014 Jul;109(7):950-66; quiz 967. doi: 10.1038/ajg.2014.131. Epub 2014 Jun 17. PMID: 24935270.
  3. Danan G, Teschke R. RUCAM in Drug and Herb Induced Liver Injury: The Update.Int J Mol Sci. 2015;17(1):14. Published 2015 Dec 24. doi:10.3390/ijms17010014

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R-value for Liver Injury Online calculator | ClinCaseQuest (2024)

FAQs

How to calculate R value in liver injury? ›

The R ratio is calculated by the formula R =(ALT value÷ALT ULN)÷(alkaline phosphatase value÷alkaline phosphatase ULN).

What is the R ratio for drug induced liver injury? ›

The pattern of DILI was defined according to the R value which is defined as the ratio of ALT to ALP as multiples of their upper normal limits. Hepatocellular injury is defined when R value equals more than 5, mixed injury if it is between 2 and 5, while it is cholestatic injury when R value equals less than 25.

What is the R factor for hepatocellular injury? ›

R value > 5 is suggestive of hepatocellular pattern, > 2 to < 5 is suggestive of a mixed pattern, and < 2 suggestive of cholestatic pattern (Table ​2)[15].

How do you calculate the R factor? ›

Finally, the reliability factor (R) is calculated according to R = Σ(Fobs − Fcalc)/(ΣFobs) where the sum (Σ) is over all collected structure amplitudes, Fobs, and those calculated from the obtained protein model, Fcalc.

How do I find my R-Value? ›

Use the formula (zy)i = (yi – ȳ) / s y and calculate a standardized value for each yi. Add the products from the last step together. Divide the sum from the previous step by n – 1, where n is the total number of points in our set of paired data. The result of all of this is the correlation coefficient r.

How to measure the R-Value? ›

It is simply the thickness of the insulation in inches divided by the thermal conductivity of the insulation. For example, a 2" thick sheet of insulation with a thermal conductivity1 of 0.25 Btu•in/h•ft2•°F has an R-Value equal to 2 divided by 0.25 or 8.0.

What is the scoring system for drug-induced liver injury? ›

Total scores range from less than 0 to 14 with scores of 3 or below indicating unlikely, 4-5 possible, 6-8 probable, and >8 highly probable hepatotoxicity.

What is the AST ALT ratio for drug-induced liver injury? ›

Aspartate aminotransferase (AST) isozymes are present in mitochon- dria and cytoplasm, while alanine aminotransferase (ALT) is confined to the cytoplasm. A high ratio of AST to ALT (>2 : 1) often indicates significant liver injury attributable to alcohol.

How do you calculate the ratio between AST and ALT? ›

This ratio is created by simply dividing the units of AST by the units of ALT. In healthy adults, this ratio should be around 1.15, whereas in unhealthy or liver-damaged individuals, this ratio can be as high as 6.0.

How to calculate liver damage? ›

MELD score is calculated using serum bilirubin, serum creatinine, and International Normalized Ratio (INR) and is given by the formula 9.57 × loge (creatinine) + 3.78 × loge (total bilirubin) + 11.2 × loge (INR) + 6.43. The score can be calculated using online website www.

How to measure liver injury? ›

The most common liver tests include: Liver enzymes test. Your liver enzymes include alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT). These are elevated when there's liver injury.

What is the liver injury unit score? ›

The Liver Injury Units (LIU) Scoring System was used to evaluate the severity of PALF before and after the DPMAS and PE. LIU was calculated as LIU = (3.507 × peak total bilirubin) + (45.51 × peak INR) + (0.254 × peak ammonia) [12].

How to find r value on calculator? ›

You need to turn your diagnostic on Press: 2nd, 0 to open catalog Press: x-1 to jump to the “D” section and scroll to “DiagnosticOn” Press: Enter twice and “Done” will appear Start at Step 3 again, and “r” will appear this time.

How do you calculate the value of R? ›

The value of R at atm that is at standard atmospheric pressure is R = 8.3144598 J. mol-1. K-1.

What is a good R factor value? ›

The R-value measures how well the simulated diffraction pattern matches the experimentally-observed diffraction pattern. A totally random set of atoms will give an R-value of about 0.63, whereas a perfect fit would have a value of 0. Typical values are about 0.20. A fit may not be perfect for many reasons.

How do you calculate liver damage percentage? ›

Gamma-glutamyl transpeptidase test: This test measures the level of gamma-glutamyl transpeptidase (an enzyme that is produced in the liver, pancreas, and biliary tract). This test is often performed to assess liver function, to provide information about liver diseases, and to detect alcohol ingestion.

How do you calculate future liver remnants? ›

The estimated future remnant liver function (eFLRF) was calculated by multiplying the future liver remnant volume ratio by the corrected total liver function (eFLRF = FLRV% × TLF).

How do you calculate R score in statistics? ›

r = ∑ ( x i − x ¯ ) ( y i − y ¯ ) ∑ ( x i − x ¯ ) 2 ∑ ( y i − y ¯ ) 2 . Label your variables x and y as it is easier to work with letters compared to names of variables. In this example denote 'test score (out of 10)' by x and 'hours playing video games per week' by y .

What is the formula for liver index? ›

(A): Liver index was calculated by the following formula: Liver index (%) = weight of liver/weight of body x 100%.

References

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