Hyperkalemia can be a life-threatening complication, impacting electrical conduction systems in the heart and muscle cells. The normal range of potassium is approximately 3.5–5.2 mEq/L, but dialysis patients frequently manifest pre-run levels exceeding 6.0 mEq/L. Chronic dialysis patients have a somewhat greater tolerance for potassium levels above the normal range, but the risk of cardiac arrest and ventricular fibrillation is still present.
While diet is the most common reason for hyperkalemia, additional causes include gastrointestinal bleeding and catabolism of blood from hematomas, such as from retroperitoneal bleeds or access infiltrations. Hemolysis rarely causes hyperkalemia, but it is life-threatening when it occurs. Moreover, numerous drugs, such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and mineralocorticoid receptor antagonists, can cause hyperkalemia by interfering with residual renal function and gastrointestinal tract excretion. Regardless of the cause, the clinical challenge is treatment, which must immediately address conduction problems in the heart. Conservative treatments include dextrose with insulin, intravenous bicarbonate, intravenous calcium, beta agonists, and potassium-binding resins, which either shift potassium into cells or trap potassium in the gastrointestinal tract, buying time for the patient to receive dialysis.
Rates of admission for the principal discharge diagnosis of hyperkalemia have been fairly stable, but increased slightly at the end of the study era in both the incident and prevalent dialysis populations. Prior to the advent of MS-DRGs on October 1, 2007, hyperkalemia was frequently used as a leading secondary diagnosis code, as it established a complicating condition; after the advent of MS-DRGs, this practice ended.
Regional variation in rates of admission for hyperkalemia is quite different than that observed for most other diagnoses examined in this report. Rates are highest in the Mountain and Pacific states, and lowest in the Middle Atlantic and East South Central areas. These variations may relate to different practices of treating hyperkalemia in the emergency room, in the observation room, or during a hospital admission — another example of the potential influence of the supply of care in the outpatient setting on the utilization of care in the inpatient setting. Further analyses are needed to clarify variations in practice patterns across the country.