Pearls on evaluating patients with suspected pulmonary renal syndrome in the ddx:
1. If at first you don’t see red cell casts, spin, spin again: If you have a high suspicion for glomerular disease as a cause for AKI (protein in urine and not just RBCs, Cr doesn’t improve with fluid and obstruction ruled out, good story with protean symptoms and lab markers of inflammation) you should try to spin the urine again, preferably with a fresh first void AM sample since you have a better chance of finding them! In the case we heard this morning the casts and dysmorphic reds were absent on HD #1 and then were found just like this on the subsequent hospital day!!!
2. If you see something in the lungs say something to a pulmonologist: Patients being evaluated for glomerular causes of AKI who develop new shortness of breath, oxygen requirement, or most other pulmonary complaints may need an urgent bronchoscopic evaluation since even if your suspicion is lower for pulmonary renal syndrome since finding DAH would change management.
3. Choose your renal ultrasounds wisely: Folks in the know tell us that there is a new movement afoot to try to limit the amount of renal ultrasounds that are done for AKI given that the yield is extremely low. What happens with the placement of a foley catheter generally gives you the same information and only misses “suprabladder” bilateral ureteral obstructions. Try to choose wisely!