The kidneys are paired organs in the lower back that regulate the composition of blood. They regulate the mineral content and volume of blood, signal the bone marrow to make red blood cells, help synthesize vitamin D and get rid of waste through making urine. Diseases of the kidneys can cause problems with these activities and affect the balance of protein in the body.
Nephrotic Syndrome
According to "Robbins and Cotran Pathologic Basis of Disease" by Dr. Vinay Kumar, when blood passes through the kidneys, they pass through a specialized structure called the glomerulus. The glomerulus filters the blood and delivers it to the rest of the kidneys, so that they can regulate the composition of the blood and dispose of wastes in the urine. Damage to the glomerulus, as by infections or immune disorders, causes the nephrotic syndrome. Excess protein leaks out of the blood and into the urine, so the blood levels of protein are low and the levels in urine are high. The cholesterol and fat levels in the blood rise, and the body swells with fluid. This is because the proteins help retain fluid inside the blood vessels; without proteins they leak out into the tissues.
Nephritic Syndrome
Nephritic syndromes are also caused by damage to the glomerulus with the resultant loss of protein. In addition to protein, red blood cells, which carry oxygen through the blood, are also lost. Symptoms and signs include blood in the urine, protein in the urine, though less than in the nephrotic syndrome, high blood pressure, and the retention of waste products in the blood. Urine output may also be decreased.
Kidney Failure
Persons suffering from kidney failure may have to decrease the amount of protein in the diet with the guidance of a healthcare professional such as a physician or dietitian. As noted by "Harrison's Principles of Internal Medicine" by Anthony Fauci, M.D., protein creates waste products containing nitrogen which are disposed of by the kidneys. If the protein in the diet is too high relative to kidney function, the waste, typically measured as a product called "blood urea nitrogen" or BUN, builds up. The nitrogenous waste products cause loss of appetite, confusion, sleepiness, taste changes and excessive bleeding.
References
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al; 8th Ed 2009
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al; 17th Ed 2008
