 Welcome back to our Question of the Week series, let's continue. Once again, we will hide the answer choices until we get to that point of the question. And as always, we start with the last sentence first and then read the rest of the vignette. What is the most likely to have caused this condition? A 56 year old female is recovering at the hospital from a suspected bacterial pneumonia. Over several days, she develops fever, rash, dysuria, and urinary urgency. Her analysis shows a specific gravity of 1.002 with hematuria and mild protein urea. Renobiopsy shows partial effacement of the tuberous interstitial structures with pronounced edema and infiltration of the interstitium with polymorphonucleid leukocytes, eosinophils, and lymphocytes with papillary necrosis. So what is the most likely to have caused this condition? So we know they've been in the hospital for bacterial pneumonia that tells me they're being treated with some type of medication, so I'm probably thinking this medication is causing this. Fever, rash, dysuria, urinary urgency, and then we're having these lab values and then we have our renal biopsy giving us this partial effacement of the tuberous interstitial structures and all of the infiltrates into the portions of the kidney. So let's look at our answer choices. Take a minute, come up with your answer and write your answer in the comments below. A. antibiotics. Well just from the beginning having bacterial pneumonia could mean that they're on antibiotics so I'm thinking that could be a possibility and we know antibiotics can cause some problems. Chronic hypertension probably not going to be a acute onset of all of this just due to her chronic hypertension so that's not something I'm going to look at. Lead ingestion. Once again, lead ingestion is more of a chronic problem. Not going to immediately pop up all these patients in the hospital. I'm already going to mark that out just due to this issue. Multiple myeloma. While with multiple myeloma we can see eosinophilic cast and other giant cells associated with it we're not going to see this type of presentation with multiple myeloma. So I'm going to take multiple myeloma out. And then Wegner's granulomatosis while Wegner's can cause renal damage. This is a focal segmental glomerular nephritis, not something more of an acute, probably this seems to be more of an acute interstitial nephritis. So I'm going to take E out. So that leaves me with A. So we talked about this patients in the hospital getting medications already so it could be a medication. The only one on this list is A so that leaves me with A is my final answer. And A is the correct answer. So this is, as I mentioned, acute interstitial nephritis. So what we're seeing here, fever, rash. We can't concentrate the urine so the urine has a low specific gravity and then our biopsy findings that we saw that is all classic presentation of interstitial nephritis. What causes interstitial nephritis? Drugs is going to be our most common cause. So antibiotics like beta-lactams, sulfonamides, rifampin, quinolones, all of those can cause acute interstitial nephritis. Anti-confalsant drugs can also cause acute interstitial nephritis. And then there's other organisms like bacteria and viruses that can cause it. So on the bacteria side of things, staphylococcus, streptococcus, legionella can all cause acute interstitial nephritis. And viruses like CMV, epsin bar, HIV, all of those can cause acute interstitial nephritis as well. But like we mentioned, chronic hypertension can cause some kidney issues, but it's not going to give us that interstitial inflammation and papillary necrosis. And fever and rash would just be completely out of the ordinary for chronic hypertension to cause those type of symptoms. Lead ingestion, that does damage the kidney. So this is another thing they're going to give you, a lot of things that will give you kidney damage, but they're a different type of kidney damage. So this is a chronic, long prolonged course associated with lead ingestion and lead poisoning. It's not consistent with this acute picture that we see with this particular question. And we've already mentioned multiple myeloma and how that doesn't really fit that multiple myeloma. This is our Benz-Jones proteins. And then Wegners. Wegners is a focal segmental glomerular nephritis. And this gives us those crescent formations. It does also give us some pulmonary disease. So that could confuse you a little bit. It does also give us some pulmonary disease. So a patient that doesn't present with any pulmonary disease but has the renal disease is probably going to mark that as an option out for you because of the lack of the pulmonary associations.