Hi, Thanks for writing in. Heavy breathing might be a symptoms of your general health and not specific to your kidney. It is appropriate if you can get examined by a general physician and get routine blood tests done. Anemia due to low hempoglobin counts s the commonest cause for sudden tiredness after short period of mild exertion. If you are past your middle age then getting your heat checked is also important. Abnormal thyroid hormones also cause suddenheavy breathing after exertion. The fact that it passes quickly indicates that the condition should you have any is in its mildest form and treatable with medication. Please do not worry.