The use of renal scintigraphy with technetium-99m-L,L-ethylenedicysteine in critically ill patients with acute renal failure in the intensive care unit

Background

Patients with acute renal failure (ARF) often represent a diagnostic challenge to physicians in the intensive care unit. A noninvasive test would be valuable to assist the clinicians in making differential diagnoses for these patients. Technetium-99m-L,L-ethylenedicysteine (^99mTc-EC), a new renal radiopharmaceutical, provides high quality images in patients with renal failure and its clearance resembles that of hippuran, which makes it a desirable agent to evaluate tubular function, such as in patients with acute tubular necrosis (ATN). Adequate renal uptake seemed to predict recovery of renal function.

Aim

To evaluate the diagnostic value of ^99mTc-EC renography in the diagnosis of acute renal failure in critically ill patients in an intensive care unit.

Methods

After the usual diagnostic approach, two patients were submitted to renal scintigraphy with ^99mTc-DTPA and ^99mTc-EC, and one patient to ^99mTc-EC renal scintigraphy.

Results

The first patient was hospitalized with hypertension and left renal abscess. She was submitted to left nephrectomy and evoluted to ARF, requiring hemodialysis. The ^99mTc-EC renography showed normal flow to the right kidney, and delayed and decreased activity compatible with ATN. The clearance values of ^99mTc-EC and ^99mTc-DTPA were 28.4 ml/min and 6.1 ml/min, respectively. The hemodialysis was suspended and the ^99mTc-EC clearance increased to 35 ml/min. The second patient had diabetes and hypertension, and was hospitalized with acute pulmonary edema. The ^99mTc-EC renography showed decreased flow and uptake to both kidneys without any evidence of significant excretion into collecting systems. The findings were consistent with the clinical suspect of renal cortical necrosis. The clearance values of ^99mTc-EC and ^99mTc-DTPA were 16.9 ml/min and 9.4 ml/min, respectively. The patient required hemodialysis treatment. The third patient had myocardial infarction and evoluted to shock with ARF. The ^99mTc-EC renography showed normal flow to both kidneys, and delayed and decreased activity compatible with ATN. The patient required hemodialysis. The clearance value of ^99mTc-EC was 39 ml/min.

Conclusions

For patients with acute renal failure, the ^99mTc-EC renal scan may facilitate decisions regarding the management of therapy. The use of the ^99mTc-EC renal scan in the differential diagnosis of acute renal failure appears promising in the setting of the intensive care unit.