I just spoke to my vet about your difficulty and she suggested not to write off the test results without a second opinion. She has seen extremely low readings before caused by certain diseases.
She said it could be a report error depending on where the blood work was done and the time of day when the sample was taken. If it was done outside in a reputable lab, there shouldn't be any problem. But if it was done in the veterinarian office, there is room for error.
She asked if there were any issues and I mentioned that your vet has an issue with the "raw food" feedings. She suggested, in that case, she would be looking for a second opinion by somebody who is understanding.
She's a great believer in raw food diets for animals.
Hope this helps.