Khushnaseeb Ibrahim ( PMRC Research Centre, Jinnah Postgraduate Medical Centre, Karachi. )
M. Ayub Yousufi ( Department of Biochemistry, University of Karachi, Karachi. )
S. Nazrul Hasnain ( Department of Biochemistry, University of Karachi, Karachi. )
Sarwar J. Zuberi ( PMRC Research Centre, Jinnah Postgraduate Medical Centre, Karachi. )
The reference values for AST and ALT were determined at 37°C in 0.2 ml serum from 339 apparently healthy individuals (188 males and 151 females). The normal ranges for AST and ALT varied from 1-50 units in both groups irrespective of age. Males had significantly higher levels of enzymes than females.
Age had no effect on enzyme levels in males but levels were significantly higher in females above 15 years.Using the formula (mean±2SD) most of the confidence intervals (JPMA 38: 325 1988).
Enzyme activity is striking by constant in healthy subjects, varying only ± 10 units, irrespective of diet, exercise and other physiological variations1-2 , This study reports AST and ALT levels in apparently healthy individuals residing in Karachi.
SUBJECTS AND METHODS
Levels of AST and ALT were determined in 137 (74 males, 63 females) subjects under 15 and 202 (114 males and 88 females) over 15 years of age. They were selected from hospital personnel, MCH centres, primary and secondary schools, colleges and other organisations.
General information regarding health, anthropometric measurements, diet and socioeconomic groups were recorded on a precoded proforma.
Enzyme activity in the serum stored at 0-5°C was measured spectrophotometrically at 37°C on the second day of collection using commercially prepared Hyland Kit.3 The standard curve was prepared for AST and ALT and control was monitored with each batch.
Data was scrutinized before analysis. Subjects with abnormal lipids and enzymes were excluded from the study. Mean, standard deviation, standard error of the mean and coefficient variation were calculated. The significance of the difference between mean was determined using ‘t’ test. The values of AST and ALT were also converted by logarithm in normal frequency distribution. The reference range (2.5th and 97.5th) percentiles were calculated by using parametric method mean ± 2 standard deviations.
The values for AST and ALT in this study fall within the range observed in other studies1-4-7. Some investigators stressed the clinical importance of a border line range of activity of AST and ALT.1-8-12 In this study, 2 SD deviation above the mean are considered to the upper limit of normal; therefore 2½ % of the apparently healthy subjects will appear above normal limits. Using this formula maximum mean activity of AST were 25.1 in males (range 18.9-25.1) and 10.6 (6.4—10.6) in females in Group I and in Group II, 25.7 in males (range 21.1-25.7)and 20.6 in females (range 15.8-20.6).
Significant difference in the enzyme levels reported earlier in males and females have also been observed in this study4-6 ‘k Age had no effect on enzyme values in males4-6 but levels were significantly higher in older females.
The actual observed ranges in both groups were upto 50 units for AST and ALT. This may be either due to excess intake of carbohydrates13-14 or due to subclinical liver disorders.
It is concluded that these values for AST and ALT may be used as reference values for our population.
1. LaDue, J.S., Wroblewski, F. and Karmen, A. Serum glutamic oxalacetic transaminase activity in human transmural myocardial infarction. Science, 1954; 120 497.
2. Agress, C.M. Evaluation of the transaminase test. Am. J. Cardiol 1959; 3: 74.
3. Reitman, S. and Frankel, S.A colorimetric method for the determination of serum glutanuic-oxalacetic transaminase and glutamic-pyruvic transaminase. Am. J. Clin. Pathol., 1957; 28 :56.
4. Karmen, A., Wroblewski, F. and LaDue, J.S. Transaminase activity in human blood. J. Clin. Invest., 1955; 34:126.
5. Conrad, F.G. Transarninase. N. Eng. J. Med., 1957; 256:602.
6. Bowers, G.N. Jr.,Durant, J.R., Beckett, R.S. and Tennant, R. An accurate simplification of the serumglutamic oxalacetic and pyruvic transaminase; method, observations and normal values.Am.J.Pathol., 1958;30 :1.
7. Amador, E., Massod, MY. and Franey, RJ. Characterization of the normal serum glutamicoxalacetic transaminase activity of healthy adults. Am. J. Clin. Pathol., 1967; 47 : 3.
8. Chinsky, M., Shamagranoff, G.L. and Sherry, S. Serum transaminase activity; observations ina large group ofpatients.LLab.Chn.Med., 1956; 47 :108.
9. Kattus, A. A., Watanabe, R. and Semenson, C. Diagnostic and prognostic significance of transaminase levels in coronary occulsive disease. Circulation, 1957; 15 :502.
10. Latner, A. L. and Smith, AJ. Serum transaminase/ alkahne-phosphatase ratio in differential diagnosis of jaundice. Lancet, 1958; 2: 915.
11. Woblewski, F. Increasing clinical significance of alteration in enzymes of body fluids. Ann.lntern. Med., 1959; 50:62.
12. Zimmerman, H.J. Evaluation of the function and integrity of the liver, in clinical diagnosis and management by laboratory methods. Edited by Henry J. Bed. Philadelphia, Saunders, 1979, p. 305.
13. Katchman, B.J. and Zipf, R.E. Correlation between triglycerides and glutamic-pyruvic transaminase in men on high-fat diets. Clin. Chem., 1970; 16: 118.
14. Porikos, KY. and Van itallie, T.B. Diet-induced changes in serum transaminase and triglycerid levels in healthy adult man; role of sucrose and excess calories. Am. 3. Med., 1983;75:624.