[R] measurement error model - "simple" linear regression

[Troels Ring]

Dear friends, I found the thread on this subject this summer but 
wonder whether it has been taken any further. I have an important 
medical problem where X is computed from a three independent and 
complicated measurements (exchangeable sodium and potassium and total 
body water - i.e. X = (Nae+Ke)/TBW ) and Y is serum sodium 
concentration (all data in Edelman, JCI 1958). I have the individual 
data in the paper (but have not yet had time to enter it) and Edelman 
et al in fact reported measurement errors for most individual items. 
Edelman and coworkers made a linear regression of Y on X and now I 
would like to ascertain the importance of the fact that X was 
measured with error for the utility of the formula in clinical 
practice (since I believe it is being misused by ignoring this fact - 
and more). I found in Neter, Wasserman and Kutner 3. ed a general 
discussion of the problem - but would very much like a more recent 
presentation if available and application in R.

Best wishes

Troels Ring
Aalborg, Denmark