Bladder permeability in interstitial cystitis is similar to that of normal volunteers: direct measurement by transvesical absorption of 99mtechnetium-diethylenetriaminepentaacetic acid.
Bladder permeability was directly measured with the radionuclide used clinically for detecting vesicoureteral reflux (99mtechnetium-diethylenetriaminepentaacetic acid, 99mTc-DTPA) in 10 interstitial cystitis patients diagnosed according to National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases criterion and compared to 9 sex matched, symptom-free, normal volunteers. After functional bladder capacity was determined (capacity at which the patient demands fluid inflow to stop), the bladder was emptied and 5 mCi. 99mTc-DTPA in 10 ml. of saline were infused followed by normal saline to 80% of functional capacity. This was done to normalize the patients to the same low bladder pressure, since previous studies of rabbits indicated that bladder permeability is low and not significantly different at 20% and 60% of anesthetized bladder capacity (defined as the volume producing an intravesical pressure of 20 cm. water). Radioactivity of 1 ml. serum specimens taken at 0, 2, 15 and 30 minutes after radionuclide infusion was determined in a gamma counter, corrected for radioactive decay and converted to per cent of instilled dose per whole body based on blood volume estimated from body weight for each individual. There was considerable interindividual variability in the absorption between the patients and the volunteers. Analysis of variance of these data showed no statistically significant difference between the patients and controls at any time sampled. These results indicate that while some interstitial cystitis patients have a more permeable bladder than others, the same is true for normal, symptom-free volunteers. Thus, the concept of increased bladder permeability in interstitial cystitis is not supported by this direct measurement of bladder permeability.