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Kidney Diseases

What causes low-grade fever and flank pain?



Hi, I`m a 37 year old female who was diagnosed with genetic Polycystic Kidney Disease when I was 16. I`m 5"7 and weigh 105 lbs. So far I have not had any symptoms and have seen a Neurologist for CT scans. I have numerous bilaaterll cysts on both kidneys and in the liver. About a month ago I thought I had a UTI, but it went away in 2 days. A couple of weeks later I had intense pressure and pain in my left kidney. I went to my GP who ran a urine test and said that I was fine. The following week I developed a fever, weakness and loss of appetite. I finally got into see my Nephrologist who put me in the hospital. My blood tests came back for normal kidney function, but my white and red blood cell counts were both high. I was in the hospital for 4 days on IV Cipro, but still having pain and pressure with fever. They did an US which stated the renal cysts appear to be anechoic and the renal parenchyma is mildly echogenic. My left kidney measures 13.3 x 4.7 cm and the right is 10.1 x 4.1 cm. A non-contrast Axial CT scan was performed with noted Polycystic Changes from previous CT scan done in January of 2008, but with no other information. I was discharged from the hospital four days later and still running a low-grade fever with the pain and pressure in the left kidney. I was given 5 days of oral cipro. Since discharge my fever has spiked over 101 2 times and remains constant at around 100. I pulled the CT scan from 2008 and it was done with IV contrast. The report noted that their is a higher density lesion measuring 2.2 cm in the lower pole of the left kidney which may represent a complex cyst. With my systems being the same they are treating me as one of my cysts is just infected and have changed my antibiotics to Augmentin. I`m worried that my condition may be more than just an infected cyst. Could it be possible that I have a tumor that was not seen without the contrast CT? I have lost interest in doing most of the things I did before and have also lost 10lbs. Should I make an appointment with an Urologist or is my Nephrologist on the right track? I`m so confused!!!

The CT scan also showed that I had dependent free fluid in the pelvis, the uterus is in situ and the bladder is distended. I have always had urination problems. I had a dilation when I was 2 for a narrow uretha. I have to urinte often and my bladder does not fully void. But like I said, all tests have come up negative.

I`m now starting to get pain and pressure in the right side of my kidney. I`m still very week, no appetite, very irritable and have lost interest in doing anything.


Your case is way too complicated to be analyzed just by reading a description of it -- in order to really figure out what's going on, one would have to talk to you in person, examine you, and personally look at all your lab and imaging studies.  However, here are a few thoughts that occur to me as I read over your case:

1) It is unlikely that you have a tumor -- you are pretty young; tumors are usually solid, not cystic; and they usually do not cause fever and pain.

2) I think your nephrologist is right to treat you for an infected cyst, but I wonder whether the antibiotic is right: in kidney or bladder infections, a urine culture is done, the bacteria is identified, and it is tested against a number of antibiotics to see which ones it is sensitive or resistant to, so that an appropriate antibiotic can be chosen.  With an infected cyst, the fluid in the cyst may not connect with the urine collecting system, so that a urine culture may not help. 

3) Another possibility, since you're being treated but still have fevers and weight loss (suggesting a smoldering untreated infection), is that either the antibiotics are not getting into the cyst fluid to kill the bacteria, or that the treatment has partly failed and you have an abscess (a pocket of pus) in your kidney that may need to be surgically drained.

3) The fact that you can't empty your bladder well also predisposes you to both kidney damage and urinary tract infection, because urine sitting in the bladder is more likely to become infected, and the infection may then spread upward to the kidneys.

I think that your nephrologist would be wise to refer you to a urologist and/or order more complicated imaging tests such as another CT scan or even an MRI.

Good luck, and please write back and let me know how things turn out.  I am concerned about your continuing fevers, weakness, and weight loss.  Certainly you need to have every bit of your functioning kidney tissue preserved, and a long-lasting infection may cause serious damage of the kidney.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University