Individuals with diabetes mellitus may excrete small amounts of albumin in the urine (microalbumin), which may signal the beginning of reduced glomerular filtration. Stabilizing the blood glucose level at this time may delay the progression of diabetic nephropathy. Diabetes (type I or type II) is a leading cause of renal failure. Microvascular damage caused by excessive renal exposure to glucose can lead to diabetic nephropathy. When the urine protein level reaches 30 mg/dL, which is necessary for detection by routine reagent strips, damage to the kidneys may have already occurred. Reagent strips that use a dye-binding technique rather than the traditional protein error of indicators principle are available. These strips are more sensitive and specific for albumin, detecting levels as low as 8 mg/dL.
Women in the last month of pregnancy may develop proteinuria as the first sign of impending eclampsia. The physician must evaluate the presence of protein in this situation in conjunction with other clinical symptoms.
Benign transient proteinuria may result from exposure to cold, strenuous exercise, dehydration, and/or high fever. Benign transient proteinuria may also occur during the acute phase of a severe illness.
Patients over the age of 60 have a greater chance of having protein in their urine. Occult malignancies and glomerulonephritis, which occur more frequently in older people, may be signaled by proteinuria.
Orthostatic proteinuria is a benign condition seen most often in young adults. The condition may be caused by pressure on the renal nerve. When this condition is suspected, two urine specimens are tested. One specimen is collected upon arising in the morning, and the second is collected several hours later. When this condition is present, the first morning specimen, after the patient has been in a supine position, will be negative for protein. The second specimen, taken after the patient has been upright for several hours, will be positive for protein.
