There are two main factors that cause low morning urine: First, physiological factors, the night due to dietary reasons, the intake of less water, and no water, if there are also several night urination, it will cause the next morning urine volume is low. And it is likely to lead to yellow urine color, but this is a normal physiological phenomenon, not a disease. Second, pathological factors, if a long time morning urine decrease, while the diet is normal, it may be caused by acute nephritis, acute prostatitis and other lesions occurring in the urinary system, and can not exclude the simultaneous presence of pus urine, bacteriuria, crystalluria, etc.. If the morning urine is low for a long time, it is necessary to send the morning urine for examination to find out what the cause is, so that it can be treated and avoid affecting your health as a result.