"Missing" Kidney?

  While undergoing an ultrasound to determine if I have gal stones, the technician asked me if I had ever had a severe kidney infection, or any problems with my kidney.  She then left the room and came back with a Radiologist.  The doctor proceded to do the ultrasound, and also asked me if I had ever had kidney problems.  When I asked what the problem was, I was told they could not find my left kidney.  What is the signifigance?  What are the potential problems?  What should I do at this point?
------------------------------------------------------------------------------------------------------------
Dear Dan,
The condition you describe is common.  Absence of one kidney, called renal agenesis is estimated to occur in 1 in every 1000 individuals. This condition often goes undetected unless there are associated abnormalities. In females, the associated abnormalities relate to the female organs. These females have failure of the uterus to fuse normally or abnormal development of the vagina.
In men, associated abnormalities are much less common than in women. These abnormalities include, undescended testicles and absence of the vas deferens on the same side as the absent kidney.
Long-term studies of people with solitary kidneys demonstrates no difference in life expectancy. A person can live a normal life with one kidney . There does seem to be an increased  risk of developing hypertension ( high blood pressure ). I would recommend careful yearly evaluation of your blood pressure and urine checks for protein as this is an early sign of kidney damage related to blood pressure elevation.  Also, you should avoid contact sports. This information is provided for general medical education purposes only.  Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition. More individualized care is available at the Henry Ford Hospital and its satellites (1 800 653 6568).
HFHS MD-KR
*keyword : solitary kidney