<s>[INST] My mother is 90 years old and has been quite healthy but she has starting having symptoms that I am concerned about...they drained her lungs that had a lot of fluid in them and I have noticed her ankles are very swollen. They did not tell her what may have caused the liquid in her lungs. Her kidneys and bladder have been checked and seem to be okay. [/INST] Thanks for your question on Chat Doctor. In my opinion she is having cardiac disease mostly age related cardiac failure. Due to old age possibility of underlying cardiac damage is high. Heart is responsible for fluid circulation in the body. So when its function are deteriorating then fluid is accumulated in the dependent part of the body. So edema of lower limbs appear first. Pleural cavity can also fill with fluids. So possibility of cardiac cause is high. Other possible causes are1. Low proteins2. Low hemoglobin.3. Malignancy better to consult cardiologist first and rule out cardiac cause. </s>