Hyperkalemia
Normal serum potassium levels are between 3.5 and 5.0 mmol/l; hyperkalemia refers to serum potassium >5.5 mmol/l. About 98 % of the body’s potassium is found inside cells, with the remainder in the extracellular fluid including the blood. Extreme hyper
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20
Reinhard Brunkhorst
20.1
General Facts
Normal serum potassium levels are between 3.5 and 5.0 mmol/l; hyperkalemia refers to serum potassium >5.5 mmol/l. About 98 % of the body’s potassium is found inside cells, with the remainder in the extracellular fluid including the blood. Extreme hyperkalemia is a medical emergency due to the risk of potentially fatal arrhythmias.
20.2
Medical History
Medical history should focus on kidney disease and medication use (as, e.g., ACE inhibitors, sartans, aldosterone antagonists), as these are the main causes. The combination of abdominal pain, hypoglycemia, and hyperpigmentation may be signs of Addison’s disease. Symptoms are nonspecific and generally include malaise, palpitations, and muscle weakness; mild hyperventilation may indicate a compensatory response to metabolic acidosis, which is one of the possible causes of hyperkalemia. Often, however, hyperkalemia is found during screening or after complications have developed, such as cardiac arrhythmia or sudden death.
R. Brunkhorst Klinik für Nieren-, Hochdruck- und Gefässerkrankungen, Klinikum Oststadt-Heidehaus, Klinikum Region Hannover GmbH, Podbielskistr. 380, Hannover 30659, Germany e-mail: [email protected] A.S. Merseburger et al. (eds.), Urology at a Glance, DOI 10.1007/978-3-642-54859-8_20, © Springer-Verlag Berlin Heidelberg 2014
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R. Brunkhorst
94 Hyperkalemia Medical history: - ACE inhibitors or ACE inhibitors or sartans - Dietary intake - Drug abuse
Physical examination: - Paresthesias - Muscular weakness
- Basic and specific laboratory testing - Renal ultrasound - ECG
Metabolic acidosis
• Diabetic ketoacidosis • Insufficient insuline administration • Hyperosmolality
20.3
Renal disease
• Acute or chronic loss of glomerular filtration rate • Renal tubulointerstitial disease (renal tubular acidosis, interstitital nephritis etc.)z
Adrenal disease
• M.Addison, primary • Amyloidosis • Post infectious, • Adrenalectomy • Post longterm steroids
Cellular lysis
• Hemolysis • Myolysis (burning, drugs, longterm immobility etc.) • Gastrointestinal bleeding • Catabolism
Diagnostics
Measurement of potassium needs to be repeated, as the elevation can be due to hemolysis in the first sample. Generally, blood tests for renal function (creatinine, blood urea nitrogen), acid–base status, creatine kinase, lactate dehydrogenase, glucose, and occasionally cortisol and aldosterone will be performed. Measuring plasma and urinary osmolality and calculating the trans-tubular potassium gradient can sometimes help in differential diagnosis. In many cases, renal ultrasound will be performed, since hyperkalemia often is caused by chronic kidney disease and eventually by an adrenal tumor. ECG: With mild to moderate hyperkalemia, there is reduction of the size of the P wave and development of peaked T waves. Severe hyperkalemia results in a widening of the QRS complex, and the ECG complex can evolve to a sinusoidal shape. Bradycardia, extra systoles, complex ventricular arrhythmias, an
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