Hyperkalemia: A Physiologic-Based Approach to the Evaluation of a Patient
Hyperkalemia: A Physiologic-Based Approach to the Evaluation of a Patient
Hyperkalemia generally is attributable to cell shifts or abnormal renal potassium excretion. Cell shifts account for transient increases in serum potassium levels, whereas sustained hyperkalemia generally is caused by decreased renal potassium excretion. Impaired renal potassium excretion can be caused by a primary decrease in distal sodium delivery, a primary decrease in mineralocorticoid level or activity, or abnormal cortical collecting duct function. Excessive potassium intake is an infrequent cause of hyperkalemia by itself, but can worsen the severity of hyperkalemia when renal excretion is impaired. Before concluding that a cell shift or renal defect in potassium excretion is present, pseudohyperkalemia should be excluded.
A high serum potassium level can occur in the setting of normal or altered body stores of potassium. The body has a marked ability to protect against hyperkalemia. This includes regulatory mechanisms that will excrete excess potassium quickly and mechanisms that will redistribute excess potassium into cells until it is excreted. The development of hyperkalemia in patients with diabetes is illustrative of abnormalities in both these mechanisms.
Abstract and Introduction
Abstract
Hyperkalemia generally is attributable to cell shifts or abnormal renal potassium excretion. Cell shifts account for transient increases in serum potassium levels, whereas sustained hyperkalemia generally is caused by decreased renal potassium excretion. Impaired renal potassium excretion can be caused by a primary decrease in distal sodium delivery, a primary decrease in mineralocorticoid level or activity, or abnormal cortical collecting duct function. Excessive potassium intake is an infrequent cause of hyperkalemia by itself, but can worsen the severity of hyperkalemia when renal excretion is impaired. Before concluding that a cell shift or renal defect in potassium excretion is present, pseudohyperkalemia should be excluded.
Introduction
A high serum potassium level can occur in the setting of normal or altered body stores of potassium. The body has a marked ability to protect against hyperkalemia. This includes regulatory mechanisms that will excrete excess potassium quickly and mechanisms that will redistribute excess potassium into cells until it is excreted. The development of hyperkalemia in patients with diabetes is illustrative of abnormalities in both these mechanisms.