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K+

The total body K+ content in an adult is about 2500-3000 meq. About 98% of K+ is intracellular. Concentration of K+ is about 160 meq/L intracellularly & 3.5-5.0 meq/L extracellularly. K+ is the main intracellular cation & the K+ gradient across the cell membrane provides the force behind the negative potential & electrical excitability of cells. The Na+/K+ ATPase maintains the intracellular K+ concentration. Mechanisms regulating extracellular K+ concentration: 1) renal a) most of the filtered K+ is resorbed by the proximal convoluted tubules & loop of Henle b) K+ in the urine is usually excreted by the collecting tubules under the influence of aldosterone c) factors increasing secretion of K+ in the urine 1] increased urine flow rate 2] increased distal tubule Na+ concentration 3] increased mineralocorticoids a] aldosterone b] glucocorticoids have some mineralocorticoid activity 4] increased urinary HCO3- 4) urinary K+ may vary from 5-100 meq/L 2) non-renal a) insulin: stimulates Na+/K+ ATPase because Na+ accompanies movement of glucose intracellularly b) beta-2 adrenergic receptor agonists - increase activity of Na+/K+ ATPase c) aldosterone via effects on the GI tract d) acid-base balance 1] acidosis favors movement of K+ out of cells 2] alkalosis favors movement of K+ into cells Dietary K+ occurs as potassium phosphate. Generally, green leafy vegetables, fruits, & root vegetables are good dietary sources of K+. A dietary K+ intake of 120 mEq/day or more is safe for healthy people, since excess K+ is excreted in the urine. However, patients with renal insufficiency, adrenal insufficiency, the elderly, & patients on ACE inhibitors, ARBs, NSAIDs, or potassium-sparing diuretics may need to monitor K+ intake (& serum K+). [1]

Related

dietary potassium; dietary K+ hypokalemic (K+ depleting) agent potassium (K+) in amniotic fluid potassium (K+) in blood potassium (K+) in body fluid potassium (K+) in CSF potassium (K+) in dialysis fluid potassium (K+) in gastric fluid potassium (K+) in mother's milk potassium (K+) in peritoneal dialysis fluid potassium (K+) in peritoneal fluid potassium (K+) in saliva potassium (K+) in serum/plasma/blood potassium (K+) in sweat potassium (K+) in synovial fluid potassium (K+) in vitreous fluid potassium acetate potassium bicarbonate (Effer-K, K-lyte) potassium chloride (KCl, Klor Con, Kaon-Cl, Slow-K, Micro-K, Klotrix, K Tab, K Dur, Ten-K, Cen-K, Kaochlor, Kay Ciel, K Lor, Kato, Klorvess, Kaon, K Lyte Cl) potassium citrate (Urocit K) potassium hydroxide (KOH) potassium iodide (KI, Thyro-Block, Irostat) potassium phosphate (KH2PO4) potassium [K, kalium]

General

monovalent cation

Properties

Database Correlations

PUBCHEM cid=813

References

  1. Prescriber's Letter 15(9): 2008 Potassium Content of Foods and Salt Substitutes Detail-Document#: 240904 (subscription needed) http://www.prescribersletter.com
  2. Gumz ML, Rabinowitz L, Wingo CS An Integrated View of Potassium Homeostasis. N Engl J Med 2015; 373:60-72. July 2, 2015 PMID: 26132942 http://www.nejm.org/doi/full/10.1056/NEJMra1313341

Component-of

ca+2/gamma hydroxybutyrate/k+/mg+2/na+ glucose, insulin, K+ (GIK)