Question

1. Patients suffering from burns consistently show elevated levels of potassium in their urine. Describe the mechanism behind this observation and why it is important to keep plasma potassium concentration held in a very narrow range?

Please give a detailed answer. thank you.

Answer 1

At any given time, about 98% of the total potassium in the body is located inside of cells (intracellular), with only 2% located outside of cells (in the blood circulation and in the extracellular tissue) . When burn occurs there is massive tissue damage, this will cause massive fluid shifts from the circulating plasma into the interstitial space, causing hypovolemia and swelling of the burned skin. This fluid shift, referred to as burn shock, which can induce renal failure, as the kidney become impaired, If kidney don’t work well, they can’t filter extra potassium from the blood or remove it from the body.  as a result there is elevated level of potassium levels in urine..Therefore, conditions that can cause potassium to move out of the cells into the blood circulation can increase the blood potassium levels even though the total amount of potassium in the body has not changed.

Normal potassium levels are between 3.5 and 5.0 mmol/L, levels above this is refered to as hyperkalemia, which can cause  palpitations, muscle pain, muscle weakness, or numbness, but abnormal levels can cause an abnormal heart rhythm which can result in cardiac arrest and death. If the level of potassium is low than it can cause hypokalemia, a low potassium level can make muscles feel weak, cramp, twitch, or even become paralyzed, and abnormal heart rhythms may develop if the levels of potassium are too low.