eMedicine: Hypokalemia 
Clinical article by David Garth, MD explains this condition. Includes blood level ranges, causes, common lab tests, and treatment.
http://www.emedicine.com/emerg/topic273.htmeMedicine: Hypokalemia
Eleanor Lederer, MD discusses why potassium is essential to life. Includes three mechanisms that cause a decrease in serum blood levels, risk factors, common symptoms, and medical care.
http://www.emedicine.com/med/topic1124.htm
Hypokalemia
Penn State Hershey Medical Center article explains low potassium levels, what causes it, who is at risk, how it is diagnosed, and what treatments are used.
http://www.hmc.psu.edu/healthinfo/h/hypokalemia.htm
Hypokalemia
Defines what this condition is, how it occurs, diagnosis, treatment, prognosis, and prevention.
http://www.healthatoz.com/healthatoz/Atoz/ency/hypokalemia.jsp
Hypokalemia
Wikipedia article explains what constitutes low potassium levels, signs and symptoms, causes, diagostic methods, and treatment.
http://en.wikipedia.org/wiki/Hypokalemia
Hypokalemia
Abstract discusses what this condition is, how is occurs, and why it can be dangerous.
http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Hypokalemia
Hypokalemia
Brief Mayo Clinic article explains what it is, the causes, and possible effects on the body.
http://www.mayoclinic.com/health/low-potassium/AN01143
Low Potassium
(Currently listed in Health/Nutrition/Nutrients/Vitamins_and_Minerals/Potassium - more appropriate here.)
http://www.emedicinehealth.com/low_potassium/article_em.htm
