A potassium level of 7 millimoles per liter is considered dangerous for the body, according to the Mayo Clinic. This condition is known as hyperkalemia.
Hyperkalemia is often caused by either acute or chronic kidney disease. It can also be caused by Addison's disease, a condition where the adrenal glands that sit atop the kidneys malfunction. Type 1 diabetes, an autoimmune disease that destroys the insulin secreting cells in the pancreas, can also lead to hyperkalemia.
Too much potassium can affect the heartbeat in dangerous ways, according to WebMD. It can make the heart beat arrhythmically or abnormally slowly. This is potentially life threatening.