articles - "Drug levels in the blood" vs "drug levels in blood"

The resulting molecule has a prolonged therapeutic effect even after a single-dose administration and a lower risk of adverse effects associated with fluctuations of drug levels in blood.

and

The resulting molecule has a prolonged therapeutic effect even after a single-dose administration and a lower risk of adverse effects associated with fluctuations of drug levels in the blood.

Do these sentences mean the same, or does the second imply that some particular blood is being mentioned?

I wrote "in the blood", but another translator said he would write "in blood". The ngram is as follows:

Would "in the blood" be understood as "in the blood of the patient who took the drug" and thus be for 99% of intents and purposes equal in meaning with option 1?

Answer

I didn't want to offer an answer that just went by my subjective opinion given your specific question and purpose, so I looked around the Internet for any references or style guides for medicine or medical transcription.

The most relevant one I was able to find was this document about Using Articles in Medical Writing from the English Language Unit of the Health Sciences Centre in Kuwait. That document has the following recommendations when it comes to describing blood:

I think your usage would be the third case shown above - you'd need to have previously set the context that "blood" refers to the blood of a patient who has ingested a drug, and since that context has been set, you can thereafter refer to it as "the blood" to make it clear you're referring to this specific blood sample (and not anyone's blood in general).

Using "in blood" is more general in that it refers to a typical sample of blood and not a specific sample of blood. However since you're referring to a specific subject's blood sample, it would seem more appropriate to use "in the blood" (after having set the context, as explained above).

I trust this offers the clarity you're looking for.

As a general note to all, I found that the English Language Unit mentioned earlier provides useful English resources specific to medicine on grammar, vocabulary, etc.