Specimen vol. 24 hr urine was 3000. protein, urine, qn was "<6" (range<=11 mg) 24 hr urine was "unable to calculate" (range<=149). dr says all normal. but im confused "unable to calculate" result.

24 hour urine: This may refer to the total volume of urine you produced over 24 hours.

Normal: If the protein amount is too low the lab will not quantify it. There is no information to be gained it. It is significant only if the level is high.

No need to worry: The protein content of your urine is low enough to be not a concern. Unable to calculate only means that the concentration was too low to be able to calculate 24 hour urine protein.