Blood urea nitrogen (BUN) test: The blood urea nitrogen (BUN) test measures the amount of nitrogenous waste in the patient's blood. If a patient has high levels of waste products in the blood, it indicates that the kidneys are not able to filter the blood. Healthy individuals usually have 7-20 milligrams of waste per deciliter of blood. Elevated levels indicate kidney disease.
Creatine: A creatine test is used to measure the amount of creatine in a patient's blood or urine. This helps determine how well the kidneys are able to filter small molecules, such as creatine, out of the blood. Healthy individuals usually have about 0.8-1.4 milligrams of creatine per deciliter of blood. Elevated levels indicate kidney disease.
A healthcare provider then uses the creatine test results, along with the patient's age, weight, and gender, to determine his/her estimated glomerular filtration rate (EGFR). This rate represents how well the kidneys are able to filter the blood over a period of time. Healthy men typically have EGFRs of 97-137 milliliters/minute, while females have rates of about 88-128 milliliters/minute. Lower-than-normal results indicate kidney disease.
Imaging studies: Imaging studies, such as a computerized tomography (CT) scan or magnetic resonance imaging (MRI) scan, may be performed if cancer or kidney stones are suspected. These tests take pictures of the kidneys, allowing healthcare providers to detect tumors or kidney stones.
Kidney biopsy: A kidney biopsy is the most definitive diagnostic test for most kidney disorders, including kidney cancer. During the procedure, which is performed at a hospital, a needle is inserted into the kidney and a small tissue sample is removed from either the kidney or a tumor on the kidney. Patients may be awake and receive medication to numb the area near the kidney, or patients may receive general anesthesia so that they are asleep during the procedure. The tissue is then analyzed in a laboratory. Kidney damage is indicated if scar tissue is revealed in the kidney tissue. If cancerous cells are present in the tumor tissue, cancer is diagnosed.
Patients may have to stay overnight at the hospital. Most patients experience soreness near the biopsy site. Patients should tell their healthcare providers if there is blood in their urine more than 24 hours after the test, if they are unable to urinate, if they have a fever, if they experience increased pain at biopsy site, or if they feel dizzy. In rare cases, an infection may develop.
Urinalysis (analysis of the urine): A urinalysis, also called a urine sample test, is used to measure the levels of protein in the urine. Elevated levels of protein in the urine (with or without small amounts of blood) suggest kidney disease.
signs and symptoms
Fanconi syndrome: Symptoms of Fanconi syndrome typically include increased urination (diuresis), excessive thirst, dehydration, constipation, anorexia nervosa, and vomiting. Patients usually have high levels of sugar, phosphate (hypophosphatemia), calcium, uric acid, amino acids, and protein in the urine. High levels of chloride and low levels of phosphate and calcium in the blood are also common. As a result of these electrolyte imbalances, patients may develop bone disease.
Focal segmental glomerulosclerosis (FSGS): Common symptoms of focal segmental glomerulosclerosis (FSGS) include fatigue, nausea, headache, foamy urine, weight gain, and poor appetite.
Patients with FSGS typically develop nephrotic syndrome, which is characterized by fluid retention that causes swelling (edema), foamy urine (caused by high levels of protein in the urine, also called proteinuria), abnormally low levels of albumin in the blood (hypoalbuminemia), and high cholesterol (hyperlipidemia). Edema generally develops over a few weeks, but initial symptoms may appear suddenly in some patients, with weight gain of 15 to 20 or more pounds. High blood pressure is common among most patients. It is especially common among African American men with kidney insufficiency because this population is genetically predisposed to develop high blood pressure.
Fluid in the lung cavity (pleural effusions) and fluid in the abdomen (ascites) may occur. In rare cases, fluid may build up in the sac that surrounds the heart, a condition called pericardial effusions.
Glomerulonephritis: In general, symptoms of glomerulonephritis may include dark colored urine, foamy urine (from excess protein in the urine), high blood pressure, fluid retention that causes swelling (edema), fatigue, and less frequent urination.
Kidney cancer: Most patients with kidney cancer do not experience any symptoms during the early stages of the disease. In the later stages, the most common symptom is blood in the urine (called hematuria). Other symptoms may include back pain (just below the ribs), weight loss, fatigue, and occasional fever.
Kidney stones: If the kidney stone is small, patients do not experience any symptoms of the condition. The stone may pass in the urine without any pain. However, if the stone is large enough to block the tubes inside the kidney, patients may experience intense pains that come and go. Pain may last anywhere from five to 15 minutes at a time. The pain usually begins in the lower back. As the stone moves from the kidney toward the bladder, the patients may feel pain near the abdomen, groin, or genitals. Additional symptoms may include blood in the urine, cloudy or foul-smelling urine, nausea, vomiting, and constant urge to urinate.
In some patients, the kidney stone may cause an infection. Symptoms of an infection include fever and chills.
Nephrotoxicity: Symptoms include increased urination, dark urine, blood in the urine, and frequent urge to urinate.
Bone disease: Fanconi syndrome may lead to rickets in children and osteomalacia in adults. Both of these conditions cause the bones to become softer and less dense than normal. Rickets may lead to bone deformities, stunted growth, and difficulty walking in children. Osteomalacia (rickets in adults) may cause severe bone pain and spontaneous bone fractures. Unlike rickets that is caused by poor nutrition, these conditions cannot be reversed with vitamin D supplementation.
High blood pressure: Some patients with kidney disorders, such as glomerulonephritis, may develop high blood pressure. If the kidneys do not filter the blood properly, the extra fluid and waste in the blood vessels may cause high blood pressure.
Having high blood pressure may worsen symptoms of kidney disease. This is because high blood pressure damages the blood vessels throughout the body, including the kidneys.
Kidney failure: Patients with kidney disease, including focal segmental glomerulosclerosis (FSGS), glomerulonephritis, kidney cancer, and nephrotoxicity, may develop kidney failure. When this happens the kidneys are damaged beyond repair. Kidney failure is fatal unless treated with a kidney transplant. Symptoms may include altered mental status and advanced uremia (build up of waste in the blood due to severe kidney disease). Symptoms of uremia include nausea, vomiting, bleeding, and seizures.