Urea levels

I got my 6 monthly check results back today, all was well except for one bizarre reading relating to Urea levels. My doctor was baffled as my creatinine levels were fine and kidney function was great. The urea (HST) levels were 100 mg/dl where is 50 mg/dl is the upper acceptable range.

I really don't understand this but could it be related to a high protein diet? Can anyone shed some light?

thanks for advice Noblehead, my eGFR was 75 mg/dl and creatinine was 1.1 mmol so there are no other signs of kidney disease.
I think I'm going have to cut back on the protein and / or hydrate myself better before the next test.