I have worked with blood and have gotten some readings that were a bit off but I don't think a vet every said "omg this dog has a severe organ issue" I would discuss it with your vet, you have every right and reason to express your concern that one result comes back very bad and the other two come back normal. However if he can tell you that a lab reading can be off due to equipment issues I believe it and think if you know the vet and like him I dont think its a bad idea to stay with it 