renal scintigraphy

The excretion via the kidneys is mainly ensured by two different mechanisms: on the one hand the blood is filtered very finely (glomerular filtration), on the other hand there is an active excretion of substances from the bloodstream into the small renal canals (tubular secretion). For both partial functions, there is a weakly radioactively labeled substance that can be measured in the blood or visualized with a gamma camera. For this purpose, a small amount is usually administered intravenously and the blood level determined after 20 and 40 min. The drop in blood radioactivity is a measure of excretion via the kidney. These procedures are referred to as clearance. The determination of Tc-99m-DTPA clearance to measure filtration rate and Tc-99m-MAG3 clearance is usually used to measure tubular secretion (effective renal plasma flow). When the question is asked as to whether both kidneys work differently well, a tubular excreted substance (Tc-99m-MAG3) is usually administered intravenously and an image sequence (dynamic scintigraphy) is made over 40 minutes with a gamma camera. The initial sequences are used to assess the blood flow and the functional parts of the kidneys. By taking a certain drug in advance, it is also possible to detect or rule out a blood pressure increase caused by the kidney.

The assessment of urinary outflow is carried out in the context of the above-mentioned examination using Tc-99m-MAG3 on the gamma camera. This study may be modified by the addition of a diuretic drug to accurately assess the extent of a drainage dysfunction. When asked if there is a reflux of urine from the bladder into the kidneys, the radioactive substance can also be added directly to the bladder or the patient is asked at the end of the kidney scintigraphy to empty the bladder or by pressure on the bladder tested from the outside a possible reflux.

For kidney scintigraphy they need not be sober. We even ask you to drink a lot before the examination because the renal function may be underestimated too low if you drink too little. You can take your medication as usual, unless it is after the question of kidney-related increased blood pressure (in this case, you will be given in the course of appointment information).