Potassium Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Potassium and links to relevant pages within the course.
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| Chemical Substances Present in CSF The following table lists some of the chemicals present in CSF, and their concentrations: ChemicalLevel sodium 136.0 - 150.0 m Eq/L potassium 2.3 - 2.7 m Eq/L magnesium2.4 - 3.0 m Eq/Lprotein2 - 4 mg/dL (normally diffuses across blood-brain barrier) glucose 45.0 - 60.0 mg/dL calcium2.1 - 2.7 m Eq/dLcholesterolpresent in small amounts creatinine 0.5 - 1.2 mg/dL lactic acid dehyrdogenase (LDH) present in small amounts phosphorus (inorganic)1.0 - 2.0 mg/dLurea6.0 - 16.0 mg/dL uric acid 0.5 - 3.0 mg/dL | View Page |
| False Negative Results False negative results occur when elements present in the urine interfere with either the enzymatic reaction or prevent the oxidation of potassium iodide. Examples of such substances include: large quantities of ketones aspirin ascorbic acid > 50 mg/dL with some reagent strips levadopa 5-hydroxyindoleacetic acid homogentisic acid sodium fluoride ( a preservative)A specific gravity higher than 1.020 may lower glucose reagent sensitivity, especially in the presence of a high urine pH. Exposing reagent strips to excess humidity may also reduce glucose reagent reactivity.Check the package insert of the reagent strips used in your laboratory for interfering substances that may affect glucose results. | View Page |
| The reagents used in the nitroprusside reaction are: (Choose ALL of the correct answers) | View Page |
| Patients with which of the following conditions would benefit most from washed red cells: | View Page |
| Which of the following analytes would not be significantly increased in a plasma sample as a result of hemolysis: | View Page |
| Which of the following electrolytes is most likely to be spuriously elevated in a hemolyzed specimen: | View Page |
| The most likely cause of an elevated potassium level in an apparently normal individual is: | View Page |
| Which of the following contributes most to serum osmolality: | View Page |
| Which of the following would not be considered a normal part of a routine electrolyte panel: | View Page |
| Which form of hemoglobin cannot be measured using the cyanmethemoglobin method: | View Page |
| The Joint Commission Sentinel Event Alert Since 1998, the Joint Commission has issued 25 Sentinel Event Alerts to the healthcare community. These publications include more than 50 evidence or expert-based recommendations for preventing adverse events. Sentinel Event Alerts address various error reduction topics: Transfusion reactions Inpatient suicide Infant abductions Wrong site surgery or other procedures Patient fallsLaboratory professionals can be involved in all of these types of Sentinel Events. The Joint Commission's first Sentinel Event Alert addressed the common practice of storing concentrated potassium chloride solutions in hospital nursing units. | View Page |
| Direct Error Detection
Even perfect systems designs cannot avert human limitations. Medical errors occur and they have to be detected before they can be resolved.
Sometimes people directly observe and immediately report these mistakes. | View Page |
| Types of Medical Errors Medical errors usually belong to one or more of these categories: | View Page |
| These statements describe sources of laboratory-related errors. | View Page |
| Case Marcie Moore was a phlebotomist at a community hospital in Atlanta. It was her week to collect the pediatric unit and she was on her way to the room of a newborn for which she had just received orders to draw a STAT BMP (chem-7) and bilirubin. After informing the mother of the baby about the test she needed to perform, Marcie set up to perform a heel stick on the baby. Marcie chose a site on the outer edge of the heel on the bottom of the baby’s foot ( the correct area for a heel stick) and made a small incision with a Tenderfoot lancet after cleaning the site well with alcohol.She immediately began collecting the blood in the correct tube for the BMP and bilirubin. Blood flow was not strong so Marcie squeezed the baby’s foot a little to help the blood come out faster – the newborn was screaming and Marcie could tell it was making the mother uncomfortable. She wanted to hurry and get done so the mother could hold the baby.After the chemistry tech ran the blood tests on the tube, she informed Marcie that the newborn had a panic potassium level which did not coincide with the previous blood work on the newborn. Also the chemistry instrument could not perform the bilirubin due to hemolysis. Marcie was asked to recollect the specimen. | View Page |
| Discussion Hemolysis can easily be caused by improper phlebotomy techniques. Hemolysis occurs when RBCs are broken up and hemoglobin is released into the plasma, causing it to become pink rather than its natural straw color. Hemolysis can occur by using too small a needle, pulling a syringe plunger too rapidly, expelling blood vigorously into a tube, or shaking a tube of blood too hard. Hemolysis can cause falsely increased potassium, magnesium, iron, and ammonia levels, and other aberrant lab results.In this case, Marcie did not properly wipe the site with gauze after cleaning it with alcohol, and alcohol contacting the blood could have caused RBCs to break up or hemolyze. Marcie also squeezed the baby’s foot too hard, causing hemolysis.Relevant topics:Site selection and preparation, Heelstick: Puncture, Hemolysis, Causes of hemolysis | View Page |
| Electrolytes panel (Lytes) Blood is tested for the most important electrolytes (salts):
Sodium (Na)
Potassium (K)
Chloride (Cl)
Carbon dioxide (CO2)Can be run on serum or plasma.
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| Green top tubes Contain either sodium or lithium heparin.Used for tests requiring whole blood or plasma such as ammonia or whole blood potassium.
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| Gray top tubes Contain an inhibitor of glycolysis, such as sodium fluoride.May also contain an anticoagulant such as potassium oxalate.
Used for accurate determination of glucose levels.
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| Plasma electrolytes Electrolytes are salts dissolved in water, including:Sodium (Na)
Potassium (K)
Chloride (Cl)
Bicarbonate (CO2).
Calcium (Ca) | View Page |
| Collection tubes Blood may be collected into either:Red top (clot) tubes.Speckle top tubes (serum separator tube).Gray top tubes specifically designed to preserve glucose levels.
Gray top tubes contain additives such as sodium fluoride or potassium oxalate, which prevent metabolism of glucose by blood cells.
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| Pre-analytical Errors Preanalytical Error What is it? How does it happen? What is the result? Hemolysis Red blood cells (RBCs) break and release contents of cell into plasma. Needle incorrectly positioned in vein; cells forced to squeeze through opening. Needle gauge too small; slow blood return into tube. Vigorous mixing or shaking of tube. Alcohol on skin that has not had sufficient time to dry. Some test results may be falsely elevated. (Potassium is especially affected by hemolysis.) Patient may have to be re-drawn. Clotted specimen Clumped or clotted cells in specimen that requires anticoagulated or whole blood Insufficient mixing of blood with anticoagulant in tube. Delay in mixing tube. Slow filling tube. Inaccurate test results for cell counts and clotting studies. Patient may have to be re-drawn. Tube filled to incorrect volume Too little or too much blood in tube. Tube removed from needle too quickly. Vacuum in tube has been compromised due to use of tube past the expiration date (Results in a short fill). Manual fill of tube may lead to over-fill. Test results may be unreliable due to dilution errors. Patient may have to be re-drawn. | View Page |
| Avoid Prolonged Tourniquet Time A prolonged tourniquet time may lead to blood pooling at the venipuncture site, a condition called hemoconcentration. Hemoconcentration can cause falsely elevated results for glucose, potassium, and protein-based analytes such as cholesterol.Ideally, the tourniquet should be in place no longer than one minute to prevent hemoconcentration. If the phlebotomist takes longer than one minute to assess and locate vein of choice for venipuncture, it is best practice to release the tourniquet, assemble supplies and reapply tourniquet immediately before needle insertion. | View Page |
| Order of Draw Blood collection tubes must be filled in a specific order to avoid specimen contamination from the additive in the preceding tube. The following order of draw is an accepted laboratory standard. 1. Tubes or bottles for blood cultures 2. Light-blue top tubes (sodium citrate) 3. Serum tubes (with or without clot activator) 4. Green top tubes (sodium or lithium heparin) 5. Lavender or pink top tubes (Potassium EDTA) 6. Gray (Sodium fluoride and sodium or potassium oxalate) | View Page |
| Blood Collection Tubes Most blood collection tubes contain an additive that either accelerates clotting of the blood (clot activator) or prevents the blood from clotting (anticoagulant). A tube that contains a clot activator will produce a serum sample when the blood is separated by centrifugation and a tube that contains an anticoagulant will produce a plasma sample after centrifugation. Some tests require the use of serum, some require plasma, and other tests require anticoagulated whole blood. The table below lists the most commonly used blood collection tubes. Tube cap color Additive Function of Additive Common laboratory tests Light-blue 3.2% Sodium citrate Prevents blood from clotting by binding calcium Coagulation Red or gold (mottled or "tiger" top used with some tubes is not shown) Serum tube with or without clot activator or gel Clot activator promotes blood clotting with glass or silica particles. Gel separates serum from cells. Chemistry, serology, immunology Green Sodium or lithium heparin with or without gel Prevents clotting by inhibiting thrombin and thromboplastin Stat and routine chemistry Lavender or pink Potassium EDTA Prevents clotting by binding calcium Hematology and blood bank Gray Sodium fluoride, and sodium or potassium oxalate Fluoride inhibits glycolysis, and oxalate prevents clotting by precipitating calcium. Glucose (especially when testing will be delayed), blood alcohol, lactic acid | View Page |