Diagnosis of Kidney Diseases
A stitch in time saves nine” is true for the treatment of kidney diseases. Disease like chronic kidney disease (CKD) is not curable and the cost of treatment of the end stage kidney disease (ESKD) is exorbitant. A person with such a dreaded disease can be asymptomatic, i.e. no symptoms of the disease may be apparent. If diagnosis of kidney disease is made early, it can be treated easily with medical treatment. So whenever a kidney problem is even suspected, it is advisable to go for immediate check up and early diagnosis.
Who should get their kidneys checked? Who is at high risk for developing kidney problems?
Anyone can develop a kidney problem, but the risk is more if :
• Person has symptoms of kidney disease.
• Person is diabetic.
• Person has uncontrolled hypertension.
• Family history of kidney disease, diabetes and hypertension exists.
• Person is a smoker, obese and/or above 60 years of age.
• Person has taken long term treatment with pain relievers.
• History of congenital defect of urinary tract exists.
Screening in such high risk individuals helps in early diagnosis of kidney disease.
How to diagnose kidney problems? What tests are normally performed?
To diagnose different kidney problems the doctor takes detailed history,
Early stages of chronic kidney disease are usually asymptomatic, laboratory tests are the only way of its detection. thoroughly examines the person, measures blood pressure and then advises appropriate tests. Routinely performed and most useful tests are urine tests, blood tests and radiological tests.
Different urine tests provide useful clues for the diagnosis of different kidney disease.
Routine urine tests
• It is a simple, inexpensive and very useful diagnostic test.
• Abnormality seen in urine tests provides important diagnostic clues
but normal urine report does not rule out kidney problems.
• Presence of protein in urine (proteinuria) is seen in various kidney
diseases. It should never be neglected. Presence of protein in urine
can be the first, the earliest and the only warning sign of chronic
kidney disease (and even of heart disease). For example proteinuria
is the first sign of kidney involvement in diabetes.
• Presence of pus cells in urine indicates urinary tract infection (UTI).
• Presence of protein and red blood cells provide diagnostic clue for inflammatory kidney disease (i.e. glomerulonephritis).
Microalbuminuria means that a very small amount of protein is present in urine. This test provides the first and the earliest clue for the diagnosis of kidney involvement in diabetes. At this stage the disease may be reversible with proper and meticulous treatment. Protein (albumin) is absent in routine urine test at this stage.
Urine test is very important for the early
diagnosis of kidney diseases.
Other urine tests
• 24 hours urine for albumin: In patients with the presence of protein in urine, this test is necessary to determine the total amount of protein lost in 24 hours. This test is useful to assess the severity of the disease and also the effect of treatment on the loss of protein.
• Culture and sensitivity test: This test takes about 48 to 72 hours time and provides valuable information about the type of bacteria causing UTI, the severity of infection and choice of antibiotic selection for its treatment.
• Urine test for acid fast bacilli: This test is useful to diagnose tuberculosis of urinary tract.
Various blood tests are necessary to establish proper diagnosis of different kidney problems.
• Creatinine and Urea
Blood levels of creatinine and urea reflects the function of the kidneys.Creatinine and urea are two waste products which are removed from the blood by the kidney. When the kidney function slows down, blood levels of creatinine and urea rise. Normal value of serum creatinine is 0.9 to 1.4 mg/dl and normal value of blood urea is 20 to 40 mg/dl. Their higher values suggest greater damage to kidney. Creatinine level is a more reliable guide of kidney function than blood urea level.
Healthy kidneys help in the production of red blood cells which contain hemoglobin. In a blood test when hemoglobin is low, it is called anemia.
Anemia is a common and important sign of chronic kidney diseases. Serum creatinine is a standard blood test used routinely to screen for and monitor renal failure.
However anemia can occur quite frequently in other illnesses. So anemia is not a specific test for kidney disease.
• Other blood tests
Different blood tests frequently performed in kidney patients are: blood sugar, serum protein, cholesterol, electrolytes (sodium, potassium and chloride), calcium, phosphorous, bicarbonate, ASO titer, complement etc.
• Ultrasound of kidney
Ultrasound is a simple, useful, quick and safe test which provides valuable information such as the size of kidney and the presence of cyst, stone and tumors. An ultrasound can detect blockage to urine flow anywhere in the kidney, ureters, or bladder. In chronic kidney failure both kidneys are usually found to be small in size.
• X-ray of abdomen
This test is useful for the diagnosis of stone in the urinary system.
• Intra venous urography (IVU)
IVU (also known as intra venous pyelography-IVP) is a special X-ray test. In this test radio opaque iodine containing dye (fluid which can be seen on X-ray films) is injected into a vein in the arm. This dye injected in blood stream passes through the kidney and gets excreted in to urine.
So the urine becomes radio-opaque and this causes visualization of urinary tract i.e. kidneys, ureters and bladder. A series of X-ray pictures are taken at specific time intervals which give a comprehensive view of the anatomy and the functioning of the urinary system. IVU reveals problems such as stone, obstruction, tumor and abnormalities in structure and function of the kidneys.
Most important screening tests for kidney disease are urine test, serum creatinine and ultrasound of kidney.
In case of kidney failure IVU is usually not recommended because the injected dye can damage poorly functioning kidneys. In kidney failure excretion of dye during test may be inadequate, so the purpose of the test to visualize urinary system will not be served. This test is avoided even during pregnancy. Because of availability of ultrasound and CT scan this test is used less frequently nowadays.
• Voiding cystourethrogram (VCUG)
Voiding cystourethrogram – VCUG (previously known as Micturating cystourethrogram – MCU) test is most often needed in the evaluation of urinary tract infection in children. In this special X ray test, the bladder is filled with contrast medium through catheter under sterile precautions.
After the bladder is filled, catheter is removed and the patient is asked to pass urine. X rays taken at intervals during urination show outline of the bladder and urethra. This test is helpful to diagnose backflow of urine into the ureters, and up to the kidneys (known as vesicoureteral reflux) and structural abnormalities of urinary bladder and urethra.
• Other radiological tests
For the diagnosis of certain kidney problems special tests such as CT scan of kidney and urinary tract, renal doppler, radionuclear study, renal angiography, antegrade and retrograde pyelography etc are very useful.
Other Special Tests
Kidney biopsy, cystoscopy and urodynamics are special tests which are necessary for the exact diagnosis of certain kidney problems.
Kidney biopsy is an important test useful in the diagnosis of certain kidney diseases.
A kidney ultrasound is a simple and safe test used to assess the size, shape, and location of the kidneys.
What is kidney biopsy?
In kidney biopsy a small piece of kidney tissue is removed through a needle and examined under a microscope. Kidney biopsy is performed to diagnose the exact nature of certain kidney diseases.
When is kidney biopsy advised?
In certain kidney diseases detailed history, examination and tests are unable to establish proper diagnosis. In such patients a kidney biopsy may be the only test which can clinch the exact diagnosis.
How does kidney biopsy helps?
Kidney biopsy establishes specific diagnosis of certain unexplained kidney diseases. With this information, the nephrologist is able to plan effective treatment strategy and guide patients and their family about the severity and course of the disease.
By which technique is kidney biopsy performed?
The most common method is percutaneous needle biopsy, in which a hollow needle is passed through the skin into the kidney. Another rarely used method is open biopsy which needs surgery.
How is kidney biopsy performed?
• The patient is admitted in hospital and his consent is obtained.
• Prior to biopsy it is ensured that blood pressure is normal and that the blood test reveals normal blood clotting. Medicine used for the prevention of blood clotting (e.g. aspirin) is discontinued for 1- 2 weeks prior to biopsy.
• Ultrasound is done to know the position of kidneys and to determine
Kidney biopsy is a test performed to establish exact diagnosis of certain kidney diseases.
exact biopsy site. This point is below the rib, in upper part of the waist near the back muscles.
• The patient is asked to lie face down – on stomach with the abdomen supported by a pillow/towel. The patient is fully awake during the procedure. In children kidney biopsy is done under anesthesia, so the child is not awake.
• After proper cleaning of the skin, biopsy site is numbed with local anesthesia to minimize pain.
• With the help of hollow biopsy needle, 2 or 3 small thread like piecesare obtained from the kidney. These specimen are sent to pathologist for histopathology examination.
• After the biopsy, pressure is applied to the biopsy site to prevent bleeding. The patient is asked to take rest for 6-12 hours and usually discharged the next day.
• Patient is advised to avoid heavy work or exercise for about 2-4 weeks after biopsy.
Are there any risks in kidney biopsy?
Like any surgical procedure, complications can occur in a few patients after kidney biopsy. Mild pain and passing of reddish urine once or twice is not uncommon, but it usually stops on its own. In rare cases where bleeding continues, blood transfusion is needed. In very rare cases where severe bleeding continues, emergency removal of kidney by surgery may become unavoidable.
Sometimes kidney tissue obtained may not be adequate for diagnosis (about 1 in 20). Repeat biopsy is needed in such cases.