Some people are recognised as leaking protein in the urine as a result of being upright. This is known as orthostatic proteinuria. It is thought to be the result of kinking of the renal vein. As a result, urine collected late in the day may have significant amounts of protein in it, while urine collected from first thing in the morning, after lying down all night, will be free of proteinuria in normal subjects.
There are no long term problems associated with orthostatic proteinuria.