Kidneys and Urinary Tract Problems
Like other systems in the body, the entire urinary tract is subject to diseases and disorders.
In kids, the more common problems include:
Congenital problems of the urinary tract. As a fetus develops in the womb, any part of the urinary tract can grow to an abnormal size or in an abnormal shape or position. One common congenital (present at birth) abnormality is duplication of the ureters, in which a kidney has two ureters coming from it instead of one. This defect happens in about 1 out of every 125 births and can cause repeated infections and scarring over time.
Another congenital problem is horseshoe kidney, where the two kidneys are fused (connected) into one arched kidney that usually works normally, but is more prone to problems later in life. This condition is found in 1 out of every 500 births.
Glomerulonephritis. This is an inflammation of the glomeruli, the parts of the filtering units (nephrons) of the kidney that contain a network of capillaries (tiny blood vessels). The most common form is post-streptococcal glomerulonephritis, which usually affects young children after a case of strep throat. Most kids with this type of nephritis recover fully, but a few can have permanent kidney damage that eventually requires dialysis or a kidney transplant.
High blood pressure (hypertension). High blood pressure can happen if the kidneys are harmed by disease. The kidneys control blood pressure by regulating the amount of salt in the body. They also produce the enzyme renin that, along with other substances, controls the constriction of muscle cells in the walls of the blood vessels, which affects a person's blood pressure.
Kidney (renal) failure. This can be acute (sudden) or chronic (happening over time and usually long lasting or permanent). In either form of kidney failure, the kidneys slow down or stop filtering blood effectively, causing waste products and toxic substances to build up in the blood.
Acute kidney failure may be due to many things, including bacterial infection, injury, shock, heart failure, poisoning, or drug overdose. Treatment includes correcting the problem that led to the failure, and sometimes requires surgery or dialysis. Dialysis involves using a machine or other artificial device to remove excess salts, water, and other wastes from the body when the kidneys can't.
Chronic kidney failure involves a deterioration of kidney function over time. In children, this can be due to acute kidney failure that doesn't get better, kidney birth defects, chronic kidney diseases, repeated kidney infections, or chronic severe high blood pressure. If diagnosed early, chronic kidney failure can be treated but usually not reversed. The child may require a kidney transplant at some point in the future.
Kidney stones (nephrolithiasis). Kidney stones (also called calculi) are due to a buildup of crystallized salts and minerals such as calcium in the urinary tract. They also can form after an infection. Kidney stones that are large enough to block the kidney or ureter can cause severe abdominal pain. The stones usually pass through the urinary tract on their own, but some need to be removed surgically.
Nephritis is any inflammation of the kidney. This can be caused by infection, medicines, or an autoimmune disease (such as lupus), but sometimes the exact cause isn't known. Nephritis is usually detected when protein and blood are found in the urine.
Nephrotic syndrome. This type of kidney disease leads to loss of protein in the urine and swelling of the face (often the eyes) or body (often around the genitals). It's most common in children younger than 6 years old and affects more boys than girls. It's often treated with steroids.
Urinary tract infections (UTIs). Most UTIs are caused by intestinal bacteria (such as E. coli) that are normally found in feces. These bacteria can cause infections anywhere in the urinary tract, including the kidneys. Most UTIs happen in the lower urinary tract (the bladder and urethra). UTIs affect both boys and girls, but in school-age children, girls are more likely to develop them than boys. This might be because girls have shorter urethras than boys.
Vesicoureteral reflux (VUR). In this condition, pee abnormally flows backward (or refluxes) from the bladder into the ureters. It may even reach the kidneys, where infection and scarring can happen over time. VUR tends to run in families. It's often found after a young child has a first urinary tract infection. Most kids outgrow mild forms of VUR, but some can develop permanent kidney damage and kidney failure later in life.
Wilms' tumor. The most common kidney cancer in children, this is most often diagnosed in kids between 2 and 5 years of age, and affects boys and girls equally.