Normally, the kidneys function as part of the excretory system and help the body filter waste out of the blood, which is then excreted as urine. The kidneys also help maintain a healthy blood pressure level within the body by removing excess salt and water from the blood. If the kidney or arteries within the kidney become blocked, the kidneys could sustain permanent functional damage.
Lower Back Pain
If one or both kidneys are blocked, you may begin to develop a dull aching pain within your lower back or abdominal area. Pain may be moderate to severe, depending upon the extent of kidney inflammation that occurs as a result of blockage. During an examination in a medical clinic, your doctor may tap your lower back with her hands, which can cause intense, sharp pain if you have blockage of one or both kidneys.
Blood in the Urine
Some people who have a blocked kidney may notice blood in the urine. This symptom may cause your urine to appear orange or red in color.
Urinary Tract Infection
Kidney blockage can cause urine to build up within the kidney, which can lead to a urinary tract infection. Symptoms of a urinary tract infection include fever, pain during urination or a urinary urgency in some people. Some people may also experience pain in the lower back or abdomen. Typically a urinary tract infection requires antibiotic treatment to resolve symptoms associated with this condition.
Blockage of the kidneys prevents excess fluid from being excreted from the body. This can cause areas of the body, such as the feet, ankles or hands, to expand and swell with excess fluid. The "Merck Manual of Medical Information" notes that increased fluid retention can cause weight gain to occur in some people.
High Blood Pressure
Kidney blockage might prevent the kidneys from removing excess salt and water from the blood. This can make it harder for the heart to pump blood through the body and can cause high blood pressure to develop in certain people.
Kidney infection might occur if the kidneys are blocked, a condition which can cause flu-like symptoms to occur in some people. Such symptoms include fever, body aches, nausea or vomiting.
Acute Kidney Failure
If the kidneys are completely blocked, urine production stops and causes the kidneys begin shutting down. If left untreated, this condition—called acute kidney failure—could lead to death in some cases.