The Fischer ratio is the ratio of 3 branched chain amino acids to 2 aromatic amino acids.


Analysis: HPLC


Parameters - branched chain amino acids:

(1) valine (Val)

(2) leucine (Leu)

(3) isoleucine (Ile)


Parameters - aromatic amino acids:

(4) phenylalanine (Phe)

(5) tyrosine (Tyr)


Fischer ratio =

= SUM(molar concentrations of Val, Leu and Ile) / SUM(molar concentrations of Phe and Tyr)



• Healthy children have a mean Fischer ratio of 3.1 (+/- 0.6).

• A patient with severe liver disease will have a low Fischer ratio (< 2).


Uses of the ratio:

(1) to characterize a type of nutritional support for its amino acid composition

(2) to describe the nutrition status of patients with liver disease

(3) to describe the nutritional status of patients in the ICU


Administration of branched chain amino acids has nitrogen sparing effects.


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