Code 764 vs 765.

What are the conditions that cause a physician to assign a code from the 764 series vs. the 765 series for low birth weight? I understand there are different terms used in the definition of each code, but the terms are so synonymous that I don’t see a clear, repeatable circumstance stating why one code is assigned over another.

re: Code 764 vs 765.

The codes from the category 764 require the assignment of a fifth digit to denote the birthweight from what I can tell they all seem to indicate malnutrition.
The codes from 765 caregory also require the assignment of a fifth digit to denote low birthweight, there is also a note that if you use 765.0-765.1 you need to use an additional code to indicate the weekes of gestation (765.20-765.29) basically how I see it is to supply extra documentation about the possible reason for the low birth weight.
So from what I looked at in the coding book the 764 set of codes I would use if the physician states "malnutrition", if he states "low birth weight" then I would go with the 765 code set. You may want to look for guidelines on the clinical indicators of malnutrition.
I know that when we have a patient that a physician gives a DX of protein calorie malnutrition some things we have to look for is does the physician state that the patient has muscle wasting, cachexia, non healing skin lesions, loss of subsequent fat or, a nutrition consultation. If that is the case then I would go with the 764 codes but, if those are not indicated I would use the 765 codes.