Extraction of phenotypes from gp_clinical

Hello,

I am trying to extract a variable from the GP Clinical dataset, specifically focusing on serum prealbumin levels. I have reviewed the relevant READ2/CTV3 codes from the 592 field and identified potential codes such as '44MM.' and 'XaIoc' listed in the data dictionary. However, I haven't been able to retrieve this information from the GP Clinical file.

Could anyone advise on how to query the GP Clinical dataset to obtain these values? I also checked field 42040, but it seems this variable is missing there.

Additionally, I understand that the GP data is censored around 2016/2017. Still, I believe it should be possible to retrieve this information for individuals with earlier records, even if the sample size is smaller. Any guidance on how to proceed would be greatly appreciated.

Regards, 

Akhil