SAP scintigraphy is a method to visualize large deposits of amyloid in the human body. SAP is a human protein (serum amyloid P component) that binds to amyloid in many organs and tissues, such as liver, spleen, kidneys, adrenal glands, bone marrow, and joints (but unfortunately not the heart). After binding SAP to a small quantity of radioactive iodine (123-I), sites of the body that bind to SAP show uptake of 123-I and can be visualized by scintigraphy. The SAP has been isolated and purified from the blood of healthy donors, thoroughly screened to avoid possible blood-borne infections. The amount of radioactivity is comparable with a series of radiographs used for investigation of the bowel or the kidneys.
The morning of the day of the procedure (in our hospital on Wednesday morning around 11.00 a.m.) you will first drink an iodine solution (Lugol), mixed with water. This "cold iodine" protects the thyroid gland against massive uptake of radioactive iodine bound to SAP. Iodine is a normal food constituent and leaves also your thyroid after some time. However, it is important that you are not allergic to iodine.
Before the administration of SAP some essential quality checks (iodine binding, calcium dependent binding) will be performed. Quality should be within well-described limits. Sporadically these standards are not met, the procedure will not take place at that particular day, and the procedure will be transferred to a different date.
You
do not need to be sober before the procedure.
About fifteen minutes after drinking the iodine solution the radiolabelled SAP is intravenously administered.
The next day (about 24 hours after SAP administration) a tube of blood is taken and the collected 24-hour urine is taken to the laboratory. The SAP scintigraphs will be made at that time. You will lie quietly in supine position. Above you and below you a gamma camera will move, measuring the radioactivity of different sites of your body. You will be asked not to move during these four periods of about 15 minutes. Although allergy for iodine or SAP may be a possible adverse reaction, it is very uncommon. In a very small number of patients only some itching has been seen after the procedure.
On Wednesday morning the procedure takes about half an hour, from the drinking of the iodine solution until the administration of SAP. The first 24 hours after SAP administration you will collect all urine and take it with you Thursday morning.
On Thursday a tube of blood will be drawn and this tube as well as the collected 24h-urine will be delivered to the laboratory of Nuclear Medicine. Combined with the scintigraphic procedure, this all will probably take about one hour.
No
details.