### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
In December 0f 2013, I fractured my collar bone. I did not seek medical treatment for it. the following may, I was diagnosed with pinched nerves, low hemoglobin and iron levels. With the help of vitamins and iron pills, my hemoglobin and iron levels have been brought back up. But I am experiencing a lot of fluid build up in my knees, and have to awaken about four times nightly to urinate. I have been for a cat scan and an MRI, xrays and blood test have all come back negative for any sign of disease. My doctor cannot explain the fluid retention on my knees, and I cannot get any form of relief as the fluid buildup is causing me discomfort at night. I am a 52 year old male, in good health, who went from a healthy and active 130 lb man, to a thin and frail man with a weight of 111 lbs, within six months. I cannot gain any weight. overall, I feel great, but have no muscle mass left which leaves me sore and stiff by the end of the day. I have been to numerous specialists who cant find a cause. The pinched nerve was in my neck and does not bother me anymore. what I would like to know is what is causing the fluid retention in my knees, and how can I alleviate the discomfort?

### output:

Hi, dairy have gone through your question. I can understand your concern. You have effusion in your knee.  There are many causes.  You may have reactive arthritis, rheumatoid arthritis, gouty arthritis, bacterial infection or something else.  You should go for aspiration of that synovial fluid and go for routine and microscopic examination of synovial fluid.  It gives clear idea regarding cause.  Then start treatment accordingly. Hope I have answered your question, if you have doubt then I will be happy to answer. Thanks for using Chat Doctor. Wish you a very good health.