Proteinuria is the medical term that refers to the presence of protein in urine. The presence of a small amount of protein in the urine can be a benign condition, but high levels of protein excreted in the urine can indicate kidney problems. The kidneys filter blood, and remove all waste materials and toxins from it. These wastes or harmful substances are then excreted in the form of urine.
The kidneys contain numerous small glomeruli to carry out this filtering activity. Protein molecules are usually too large to pass through these glomeruli. So, urine usually does not contain protein. Therefore, presence of protein in the urine can be a sign that there is something wrong with the glomeruli or the kidneys. Proteinuria can affect both adults and children, and it can be persistent or transient. It can be caused by a benign or serious condition.
Exercise, Stress, and Illness
Though diseases of the kidneys and the glomeruli can be associated with proteinuria, transient proteinuria is usually caused by some benign conditions. Strenuous physical activity or exercise is one of the most common factors that can cause a temporary rise in the level of urine protein. Other factors that can cause transient proteinuria in children are, emotional stress, infections, fever, exposure to extreme cold or heat, administration of epinephrine, febrile illnesses, and seizures.
Another common cause of protein in urine is orthostatic proteinuria. This is a benign condition characterized by elevated urinary protein excretion during the day when the child is in upright position. At night, when the child is sleeping, the amount of protein excreted in urine is normal. Orthostatic proteinuria is not associated with any kidney disease or disorder. So, laboratory findings and kidney biopsies of the affected child are usually normal, except for the presence of excess protein in urine during daytime. What causes this benign condition is not known, but children often outgrow this condition before they reach adulthood.
Childhood Nephrotic Syndrome
Persistent proteinuria can be caused by glomerular diseases or diseases that impair the filtering activity of the glomeruli. One of the most common causes of proteinuria in children is nephrotic syndrome, that commonly affects children in the age group of 2 to 5 years. However, nephrotic syndrome is not a single disease. Rather, it refers to the set of signs and symptoms that usually occur simultaneously. Childhood nephrotic syndrome can be caused by several conditions, of which minimal change disease is quite common.
The condition is called minimal change disease, as the kidneys appear normal or nearly normal with normal biopsies. Though what exactly causes this disease is not known, it is suspected to be associated with changes in the immune system, or immune reactions to some unknown factors. The condition usually does not cause kidney failure in children, and most children outgrow this condition in their late teens or early adulthood.
Two other conditions that can cause childhood nephrotic syndrome and proteinuria are, Focal segmental glomerulosclerosis (FSGS) and Membranoproliferative glomerulonephritis (MPGN). Both the conditions can cause scarring or deposits in the glomeruli. The exact causes of these conditions are not known with certainty. Apart from these, a child can have congenital nephrotic syndrome, which has no cure and which can eventually cause kidney failure. Nephrotic syndrome can also be caused by conditions like diabetes, systemic lupus erythematosus (SLE), leukemia, and glomerulonephritis.
Signs and Symptoms
This condition may not produce any symptoms, especially in the early stage, or when the level of protein in urine is low. The presence of high amounts of protein in urine can make it foamy. When urine is expelled from the body, protein present in it comes in contact with air and reacts. This causes the appearance of foam or bubbles.
Severe proteinuria can cause a significant loss of protein, especially albumin. Proteins help hold water inside the blood vessels. So, the loss of a large amount of proteins from blood causes water or fluid to pass into the tissues. This causes edema or water retention that can manifest in swelling, especially swelling of the hands, face, feet, abdomen, and around the eyes. Additionally, the affected child may become more susceptible to infections, and he or she may experience excessive fatigue and loss of appetite.
Treatment of Proteinuria in Children
To treat proteinuria effectively, it is important to ascertain its underlying cause. If it is caused by orthostatic proteinuria, then no treatment is required. But if it caused by bacterial infections, appropriate antibiotics can be required for alleviating the condition.
If your child is diagnosed with the minimal change disease, then his or her pediatrician can prescribe prednisone, a steroid drug. Most children respond well to this drug, which however can cause several side effects if administered for a long time. The protein in urine and edema usually disappear within a week or two after taking this drug.
However, minimal change disease is characterized by relapses, which can be frequent in some children. The prognosis of this disease is usually good, and if your child does not have a relapse for more than 3 years, then chances are quite good that he or she won't experience the condition again.
If the child does not respond to steroid drugs, or experiences uncomfortable side effects, the physician may recommend an immunosuppressant drug. However, immunosuppressants can increase the susceptibility to infections, and cause hair loss and decreased production of blood cells. Children having frequent relapses are sometimes given a cytotoxic agent.
Cytotoxic agents are also used for treating FSGS and MPGN, as prednisone is not effective in treating these conditions. ACE inhibitors have been found to be effective in preventing the leakage of protein in the urine in children with nephrotic syndrome. Apart from these, diuretics are often prescribed to facilitate the expulsion of excess water from the body, and thus, reduce the swelling caused by edema.
Congenital nephropathy on the other hand, is an inherited condition that cannot be cured. Children suffering from this condition usually require kidney transplantation, as congenital nephropathy can eventually cause kidney failure. In the meantime, you can reduce your child's salt intake, and limit the consumption of processed food. This may help reduce the swelling associated with edema or water retention.
The presence of a small amount of protein in urine is usually not associated with a serious condition. But still, it is better to get the condition properly evaluated with the help of a physician, in order to rule out the possibility of serious kidney diseases.
Disclaimer: This article is for informative purposes only, and should not be treated as a substitute for professional medical advice.