presence of protein in the urine, usually as albumin. Protein is not normally found in the urine of healthy persons, but it sometimes occurs in young people and pregnant women who have urinated from an upright position; this condition, called orthostatic proteinuria, is harmless. Light proteinuria is associated with diseases such as kidney infections and congestive heart failure; heavy proteinuria (excretion of more than 4 g of protein per day) indicates serious kidney disease.