Delayed transit time after Lasix administration points towards impaired renal function. Specifically, a Tmax (time to maximum activity) exceeding 20 minutes suggests significant obstruction or impaired nephron function.
A significantly reduced excretion fraction (EF) – below 10% – strongly indicates significant unilateral or bilateral renal obstruction. Consider the patient’s clinical presentation; a low EF coupled with elevated creatinine levels confirms the diagnosis of compromised renal function.
Asymmetrical curves between kidneys reveal unilateral dysfunction. Focus on the kidney with the poorer performance to pinpoint the exact problem. Significant differences in Tmax between kidneys warrant further investigation, possibly including renal ultrasound.
Note the pattern of the curves. A prolonged excretion phase suggests chronic changes like nephrosclerosis or scarring. In contrast, a flat curve points towards severe obstruction or renal atrophy. This necessitates correlation with clinical data and other imaging modalities like CT scan.
Remember to consider pre-Lasix function. Compare the pre and post Lasix results. A dramatic fall in function points towards a significant obstruction that’s responsive to Lasix.
Always integrate renogram findings with patient history, blood tests (creatinine, BUN), and other imaging studies for a conclusive diagnosis. A multidisciplinary approach ensures accurate assessment and appropriate management.
