Healthy Ranges for ALT Levels Are Lower Than Current Standards

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NEW YORK (Reuters Health) Jul 01 - "Healthy ranges" for serum alanine aminotransferase (ALT) levels may actually be about 10 U/L lower than the currently recognized upper range of normal, Italian investigators report in the Annals of Internal Medicine for July 2.

However, the Italian authors' suggestion that the upper limits of normal for ALT be revised downward would overwhelm the healthcare system with patients whose ALT levels indicate a relatively benign form of liver disease, Dr. Marshall M. Kaplan says in an accompanying editorial.

Dr. Daniele Prati and associates, of the Centro Trasfusionale e di Immunologia dei Trapianti in Milano, measured ALT levels of first-time blood donors between 1995 and 1999 in Italy. These included 6835 individuals who tested negative for hepatitis B and C, HIV, and syphilis. They also evaluated 209 blood-donor candidates with confirmed anti-hepatitis C virus reactivity between 1990 and 1999.

Median ALT levels were 15 U/L in men and 9 U/L in women. The authors separately analyzed results for the nearly 4000 persons at lowest risk for liver disease. Based on 95th percentiles, they defined healthy serum ALT levels as those below 30 U/L for men (currently 40 U/L) and below 19 U/L for women (currently 30 U/L).

Current reference limits applied to the patients with hepatitis C virus yielded a sensitivity and specificity of 39.7% and 97.6%. Using their newly derived limits, they observed a sensitivity of 61.1% and a specificity of 92.3%.

"These revised values are superior to the previously established limits for identification of persons at risk for liver disease, but must be used flexibly," Dr. Prati and his team suggest. They advise clinicians to investigate patients with repeatedly abnormal ALT levels with serum biochemistry analyses, hepatitis virus tests and hepatitic ultrasonography.

But keep in mind, they add, that results should be interpreted differently for an individual with chronic hepatitis C infection who is lean and has normal serum lipid levels, compared with an individual who is overweight.

Dr. Kaplan of Tufts-New England Medical Center in Boston notes that a few patients with asymptomatic hepatitis C might be identified using the lower limits, but there is little evidence that such patients benefit from treatment.

Ann Intern Med 2002;137:1-9,49-51.




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