Final answer:
The most dangerous manifestations of hyperkalemia include life-threatening cardiac arrhythmias and effects on the central nervous system, like mental confusion and respiratory muscle weakness. These can lead to immediate fatality, and conditions such as renal failure and Addison's disease can exacerbate it.
Step-by-step explanation:
The most dangerous manifestations of hyperkalemia are related to cardiac and central nervous system functions. Elevated levels of potassium in the blood can cause life-threatening cardiac arrhythmias, which can lead to the heart seizing and a cessation of blood pumping. This condition can be immediately fatal. Central nervous system effects may include mental confusion, numbness, and weakened respiratory muscles.
Cardiac arrhythmias pose a significant risk because they disrupt the electrical impulses that coordinate the heartbeat. If the heart cannot relax properly after a contraction due to the inability of cells to repolarize, this can lead to an ineffective heartbeat or cardiac arrest. In addition to these issues, skeletal muscle weakness can occur, which can affect respiratory function and lead to respiratory paralysis.
Conditions leading to hyperkalemia include renal failure, severe dehydration, and Addison's disease due to decreased excretion of potassium by the kidneys. Severe outcomes of untreated hyperkalemia may also include fever, hypotension, and in extreme cases, kidney failure and death.