(Renal Scan, Renogram, Renal Scintigraphy)
A kidney scan is a specialized radiology procedure used to assess the function and structure of the kidneys, as well as the perfusion (blood flow) to the kidney tissue.
A kidney scan is a type of nuclear radiology procedure. This means that a tiny amount of a radioactive substance is used during the procedure to assist in the examination of the kidneys. The radioactive substance, called a radionuclide (radiopharmaceutical or radioactive tracer), is absorbed by normal kidney tissue.
The radionuclide used in kidney scans is usually a form of either technetium or iodine. The specific radionuclide used in a kidney scan depends on the type of information needed. Once absorbed into the kidney tissue, the radionuclide emits a type of radiation, called gamma radiation. The gamma radiation is detected by a scanner, which processes the information into a picture of the kidneys.
By measuring the behavior of the radionuclide in the body during a nuclear scan, the physician can assess and diagnose various conditions, such as tumors, abscesses, hematomas, organ enlargement, or cysts. A nuclear scan may also be used to assess organ function and blood circulation.
The areas where the radionuclide collects in greater amounts are called “hot spots.” The areas that do not absorb the radionuclide and appear less bright on the scan image are referred to as “cold spots.”
Other related procedures that may be used to diagnose problems of the kidney include abdominal X-ray, kidney, ureters, and bladder (KUB) X-rays, computed tomography (CT scan) of the kidney, kidney ultrasound, intravenous pyelogram (IVP), cystography, cystometry, cystoscopy, renal angiogram, uroflowmetry, renal venogram, or a kidney biopsy. Please see these procedures for additional information.
The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.
The kidneys and urinary system keep chemicals, such as potassium and sodium, and water in balance, and remove a type of waste, called urea, from the blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.
Two kidneys, a pair of purplish-brown organs, are located below the ribs toward the middle of the back. Their function is to:
The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.
There are several types of kidney scans used to evaluate the kidneys. One or more different types of scans may be performed during a single procedure, depending on the type of information needed to diagnose the kidney condition. A renal scan is particularly useful when a patient has a known sensitivity to contrast media or underlying renal insufficiency.
To evaluate perfusion to the kidney tissue, a renal blood flow scan may be done. This type of scan may show decreased blood flow to the kidneys due to a blockage or narrowing of blood vessels to the kidneys. A renal blood flow scan may also be used to assess renovascular hypertension (high blood pressure in the kidney’s blood vessels), rejection of a transplanted kidney, or the presence of renal cell carcinoma (cancer of the kidney).
A renal structural scan may be used to examine the structure of the kidneys. Conditions that may affect the size and/or shape of the kidneys include tumors, cysts, abscesses, and congenital disorders. This type of scan may also be used to detect rejection of a transplanted kidney.
The function of the kidneys can be assessed by a renal function scan (renogram). This scan measures the amount of time needed to absorb and/or excrete the radionuclide. A renal function scan may be repeated periodically to assess the response of the kidneys to treatment.
One of the primary causes of kidney problems is renovascular hypertension. A renal hypertension scan may be performed to detect this condition, as well as the source of the condition. A renal hypertension scan may also be used to assess the potential response of the renal blood pressure to treatments such as medication, surgery, or vascular procedures such as angioplasty.
Obstruction of one or more portions of the urinary tract can cause kidney problems. A renal obstruction scan may be performed to assess the presence and location of an obstruction.
There may be other reasons for your physician to recommend a kidney scan.
The amount of the radionuclide injected into your vein for the procedure is small enough that there is no need for precautions against radioactive exposure. Most of the radiation is gone from the body within 24 hours. The injection of the radionuclide may cause some slight discomfort. Allergic reactions to the radionuclide are rare, but may occur.
For some patients, having to lie still on the scanning table for the length of the procedure may cause some discomfort or pain.
Patients who are allergic to or sensitive to medications, contrast dyes, or latex should notify their physician.
If you are pregnant or suspect that you may be pregnant, you should notify your physician due to the risk of injury to the fetus from a kidney scan. If you are lactating, or breastfeeding, you should notify your physician due to the risk of contaminating breast milk with the radionuclide.
There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.
Certain factors or conditions may interfere with the accuracy of a kidney scan. These factors include, but are not limited to, the following:
A kidney scan may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician's practices.
Generally, a kidney scan follows this process:
While the kidney scan itself causes no pain, having to remain still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.
You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.
You may be instructed to drink plenty of fluids and empty your bladder frequently for about 24 hours after the procedure to help flush the remaining radionuclide from your body.
The IV site will be checked for any signs of redness or swelling. If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your physician as this may indicate an infection or other type of reaction.
You may resume your usual diet and activities, unless your physician advises you differently. Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.
The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your physician. Please consult your physician with any questions or concerns you may have regarding your condition.
This page contains links to other websites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these websites, nor do these sites endorse the information contained here.