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. 2008 Mar 24;168(6):663-6.
doi: 10.1001/archinternmed.2007.131.

Influence of local reference populations on upper limits of normal for serum alanine aminotransferase levels

Brent A Neuschwander-Tetri, Aynur Unalp, Michael H Creer; Nonalcoholic Steatohepatitis Clinical Research Network
Collaborators

Influence of local reference populations on upper limits of normal for serum alanine aminotransferase levels

Brent A Neuschwander-Tetri et al. Arch Intern Med. .
No abstract available

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Conflict of interest statement

The authors report no financial conflicts of interest.

Figures

Figure 1
Figure 1
Reference ranges for serum ALT reported by the 11 NASH CRN laboratories. The bars indicate the reference ranges; the upper limit for women varied from 31 U/L in laboratory B to 55 U/L in laboratory E; the upper limit for men varied from 35 U/L in laboratory A to 79 U/L in laboratory K. The lower limit ranged from 0 to 12 U/L.
Figure 2
Figure 2
Mean ALT values for CAP sample C15. The gray bars indicate the laboratory specific means of replicate analyses and the thin line error bars indicate ± 1 SD in each direction; four laboratories (A, D, J, K) did not provide standard deviations of their results. The national machine specific mean ± 1 SD in each direction for the analyzer used in each laboratory is indicated by overlying the thick line error bars. The results from most laboratories were within 2 U/L of the national mean for their specific analyzer; laboratory A deviated the most from the national mean yet the difference was still only 4.9 U/L, indicating that laboratory performance was generally excellent.
Figure 3
Figure 3
The ALT activity of one standardized sample (C15) reported by 11 different laboratories is expressed as a multiple of the gender-specific ULN for those laboratories. The disparate ULN values reported by different laboratories causes the results of this one sample to be variably interpreted as 0.66 to 1.75 × ULN if it came from a man and 0.87 to 1.73 × ULN if it came from a woman. If this sample was from a woman, it would be reported as normal by 3 laboratories (E, F, G) and elevated by the other 8 (Figure 3). If it was from a man, it would be reported as normal in 7 laboratories and elevated in 4 (A, B, C, D)
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