A person with a kidney disorder may or may not have any symptoms. Indeed, some people do not have any symptoms until the damage is severe. Blood in the urine is a sign there is damage at some point along the urinary tract. A high amount of protein in the urine is usually a result of damage to the kidney capillaries.
Proteinuria
Proteinuria is the medical term for an abnormal amount of protein in the urine, which for adults is 150 to 160 mg in 24 hours, according to Suzanne Watnick, M.D., Director of the Dialysis Unit at the Portland Veterans Association Medical Center, in "Current Medical Diagnosis & Treatment." A high amount of protein in the urine can be the result of strenuous exercise, illness, a disease called multiple myeloma which produces too many proteins in the plasma, a kidney disorder in its capillary network or a kidney disorder in its tubules.
Nephrotic Syndrome
A disorder in the glomeruli, or the capillaries of the kidneys, is the most common reason for someone to have a high amount of protein in their urine, per Seyed-Ali Sadjadi, M.D., Associate Professor of Medicine at the Loma Linda University School of Medicine, in "The Merck Manual for Healthcare Professionals." As a result, people develop nephrotic syndrome in which they are swollen, have more than 3,500 mg of protein in their urine within 24 hours and have an abnormally low amount of the albumin protein but a high amount of lipids in their bloodstream.
Types of Nephrotic Syndrome
There are several types of nephrotic syndrome. Dr. Sadjadi writes in "The Merck Manual for Healthcare Professionals" that the most common types to cause proteinuria in an adult are diabetic nephropathy, membranous nephropathy and focal segmental glomerulosclerosis. Diabetes mellitus can damage the kidneys and cause diabetic nephropathy. People with hepatitis B can develop membranous nephropathy, while obesity can cause focal segmental glomerulosclerosis. The focal segmental type is also a common cause of high amounts of protein in the urine of older children, while a type of nephrotic syndrome called minimal change disease affects young children.
Disorders in the Kidney Tubules
The kidneys create urine within their long tubules, and damage to these tubules can result in high protein levels in the urine they create. This damage can be the result of disorders such as the kidneys not getting enough oxygen, the tubules getting damaged by certain medications or toxins or Fanconi syndrome. Fanconi syndrome is a disease that affects the beginning part of a tubule, which does not allow the kidneys to hold onto protein, glucose and phosphate, as explained by Flavio Vincenti, M.D., Clinical Professor of Medicine and Nephrology at the University of California School of Medicine, in "Smith's General Urology."
Evaluation of Proteins
A person with symptoms of a kidney disorder will need a thorough physical exam and several tests. In "Current Medical Diagnosis & Treatment," Dr. Watnick writes that the evaluation for protein in the urine starts with the urine dipstick, which measures the amount of albumin protein in the urine excreted at the office visit. Adding a substance called sulfosalicylic acid to the urine sample can determine if the proteins are being produced by a disease called multiple myeloma, instead of a result of kidney damage. The next step involves measuring the amount of protein within a 24-hour period.
References
- "Current Medical Diagnosis & Treatment 2011"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2011
- "Smith's General Urology"; Emil Tanagho, M.D., Jack McAninch, M.D.; 2008
- The Merck Manual for Healthcare Professionals: Proteinuria
