Sorted By Test Name - Mayo Medical Laboratories

KUR
8527
FPOTW
92002
with rapid K infusion.
Useful For: Evaluation of electrolyte balance, cardiac arrhythmia, muscular weakness, hepatic
encephalopathy, and renal failure Potassium should be monitored during treatment of many conditions but
especially in diabetic ketoacidosis and any intravenous therapy for fluid replacement.
Interpretation: Potassium levels 6.0 mmol/L are potentially life-threatening. Levels >10.0 mmol/L are, in most cases,
fatal.
Reference Values:
> or =12 months: 3.6-5.2 mmol/L
Reference values have not been established for patients that are less than 12 months of age.
Clinical References: Tietz Textbook of Clinical Chemistry, 4th edition by CA Burtis, ER Ashwood,
DE Bruns. WB Saunders Company, Philadelphia, 2006;27:984-987; 2006;46:1754-1757
Potassium, Urine
Clinical Information: Potassium (K+) is the major intracellular cation. Functions of potassium
include regulation of neuromuscular excitability, heart contractility, intracellular fluid volume, and
hydrogen ion concentration. The physiologic function of K+ requires that the body maintain a low
extracellular fluid (ECF) concentration of the cation; the intracellular is 20 times greater than the
extracellular K+concentration. Only 2% of total body K+ circulates in the plasma. The kidneys provide
the most important regulation of K+. The proximal tubules reabsorb almost all the filtered K+. Under the
influence of aldosterone, the remaining K+ can then be secreted into the urine in exchange for sodium in
both the collecting ducts and the distal tubules. Thus, the distal nephron is the principal determinant of
urinary K+ excretion. Decreased excretion of K+ in acute renal disease and end-stage renal failure are
common causes of prolonged hyperkalemia. Renal losses of K+ may occur during the diuretic (recovery)
phase of acute tubular necrosis, during administration of non-potassium sparing diuretic therapy, and
during states of excess mineralo- corticoid or glucocorticoid.
Useful For: Urine K+ is useful in determining the cause for hyper- or hypokalemia.
Interpretation: Hypokalemia reflecting true total body deficits of K+ can be classified into renal and
nonrenal losses based on the daily excretion of K+ in the urine. During hypokalemia, if urine excretion of
K+ is 30 mEq/d in a hypokalemia setting is inappropriate and indicates that the kidneys are the
primary source of the lost K+.
Reference Values:
17-77 mmol/24 hours
Clinical References: 1. Tietz Textbook of Clinical Chemistry. 3rd edition. Edited by CA Burtis, ER
Ashwood. Philadelphia, WB Saunders Co, 2001 2. Toffaletti J: Electrolytes. In Professional Practice in
Clinical Chemistry: A Review. Edited by DR Dufour, N Rifai. Washington, AACC Press, 1993
Potato White (Solanum tuberosum) IgG
Reference Values: