General Serum And Urine Chemistries Notes PDF

Integrated Laboratory 1 General Serum and Urine Chemistries Notes Introduction Clinical laboratory monitoring has several uses in the management of the health care of an individual. Clinical lab tests may screen and detect, diagnose, monitor and treat different disease stat...

Integrated Laboratory 1 General Serum and Urine Chemistries Notes Introduction Clinical laboratory monitoring has several uses in the management of the health care of an individual. Clinical lab tests may screen and detect, diagnose, monitor and treat different disease states. They may allow for clinicians to evaluate a patient’s adherence to specific medications as well as monitor for adverse effects from therapy that may not be physically noticeable without laboratory testing. These notes will introduce the general definitions and chemistries that you will learn and expand upon throughout your pharmacy career. Serum, Urine and Reference Ranges As you may have learned in previous courses prior to or during your time in pharmacy school there are differences between serum and urine concentrations of specific molecules or compounds. When one states that serum concentrations are measured, what are measured are concentrations of the particular lab values in extracellular fluid (ECF). Vial(s) of blood are taken from an individual and serum is separated via centrifuge and extracted. Thus, serum differs from whole blood. Urine, on the other hand, is taken from the patient—preferably from the first or second void of the day—and is usually measured “as-is” with no or very little extraction procedures. Not everyone is alike…and that is also to be said about normal serum and urine chemistries. When reference ranges are being determined, chemistries are taken from healthy adults and a bell-shaped curve is made from these ranges. Children’s reference ranges are measured the same way—and one must remember that pediatric ranges may differ from adult ranges. Most individuals will fall within a specified range but others (outliers) who are still healthy may fall outside these normal ranges. Reference ranges are specified by the middle 95% of the tested population (or 2 Standard Deviations +/- from the population mean). The bell curve illustrated below shows this distribution. Thus, a patient may present with a lab result outside the specified reference range but still be healthy. In these cases, please keep in mind that a deviation from an individual’s own normal value/range is a stronger diagnostic factor than comparison to specified reference ranges. Likewise, a disease may present in an individual who has lab values within the specified reference range. These individuals will have signs and symptoms but do not present with abnormal lab values. http://www.nonlinear.com/support/progenesis/samespots/faq/spotcheck- Due to these differences, a clinician must always treat how-it-works.aspx the patient and observe the laboratory tests. That is, if the patient is not presenting with signs or symptoms of a disease and is otherwise healthy, don’t worry about slight deviations from the specified reference ranges—the individual may still be in his/her “normal range.” pg. 1  Integrated Laboratory 1 ***Reference ranges given below are from Bakerman’s ABC’s of Laboratory Data. Different institutions may have slightly different ranges. For the purpose of this class and future Regis SOP courses, values specified by Bakerman shall be used for reference. When a laboratory value is outside the specified reference range for that molecule or compound, it may be suggestive that an individual is hyper- or hypo- of that compound. For example, the specified reference range for serum sodium is between 135 and 145 mEq/L. If an individual presents with labs measuring 130mEq/L, that individual is suggestive to have hypo-serum sodium (or hyponatremia). If an individual presents with labs measuring 5.6 mEq/L for potassium (reference range between 3.5 to 5.0mEq/L) that individual is said to have hyper-serum potassium (or hyperkalemia). As a pharmacy student you should know the different names for hypo- and hyper- chemistries. For example, you should know that the concentration of potassium in the blood is “kalemia,” sodium is “natremia,” calcium is “calcemia,” etc. These names are listed next to the different chemistries below. Some standardized laboratory tests use sex-specific ranges, which only allow patients to be classified as male or female. Makers such as hemoglobin, hematocrit, liver functions, renal functions, sex hormones, bone mineral density and iron levels are expected to change overtime for someone who has gender- affirming treatments and procedure.4 Reference ranges for nonbinary individuals are not yet established clearly. Laboratory Errors Although errors are becoming less and less over the years due to increased experience with laboratory equipment and modified procedures, errors still unfortunately exist in and outside the laboratory. Gathering accurate lab values is crucial to correctly diagnosing and treating patients. Incorrect lab values due to collection and testing errors may delay appropriate therapy, cause adverse effects due to unnecessary therapy, or provide inadequate therapy. Lab errors may occur prior to analysis, during analysis and post-analysis. Each period of analyses gives further examples in the following: Pre-Analysis Analysis Incorrect interpretation of Test ordering (ordering wrong Diagnostic or laboratory test results test at wrong time) performed incorrectly Responsible provider did not Collection of specimen is Technician procedural receive results of tests incomplete or spoiled differences and technique Patients are not notified of General administrative errors Reagents for testing are not results/ follow-up (placing coding information on correctly prepared procedures wrong test vials) Post-Analysis Laboratory errors may also be due to patient factors. Food ingestion may interfere with lab results (laboratory tests may require one to be fasting for a certain period of time). Medications also may pg. 2 Integrated Laboratory 1 interfere with testing procedures, cause false-positives or false-negatives in lab results, and cause alteration of lab values due to pharmacologic properties. These are just a few of the many possible examples of laboratory errors…can you list more specific errors or other general errors? Chem -7 Laboratory Tests (adult ranges will be given) 1. Sodium a. Reference Range: 135 to 145 mEq/L b. The major cation of extracellular fluid (ECF) c. Largely determines total body water d. Hyponatremia i. Decreased serum sodium concentration ii. May be due to decreased total body sodium with decreased total body water and increased or normal total body sodium with a larger increase in total body water (concentration of sodium is still less due to large volume of water), gastrointestinal loss (vomiting, diarrhea), diuretic therapy, sweating, and drug induced iii. Signs and symptoms mainly manifest the central nervous system as it largely determines neuronal excitement. These include alteration of mental status, confusion, weakness, seizures, cerebral edema and death. e. Hypernatremia i. Increased serum sodium concentration ii. Actions that increase concentration of sodium are that of higher sodium intake/retention compared to total body water (where water is lost to a higher extent compared to sodium) iii. Signs and symptoms of hypernatremia include thirst, restlessness, muscle spasms, seizures and death. 2. Potassium a. Reference Range: 3.5 to 5.0 mEq/L b. Major cation of intracellular fluid (ICF) c. Regulates muscle and nerve excitability d. Hypokalemia: i. Decreased serum potassium concentration ii. May be due to increased loss of potassium (drug therapy, decreased intake, diarrhea, hyperaldosteronism), increased intracellular shifting of potassium (alkalosis, insulin) iii. Signs and symptoms of hypokalemia include arrhythmias, muscle cramps and weakness e. Hyperkalemia: pg. 3 Integrated Laboratory 1 i. Increased serum potassium concentration ii. May be due to decreased excretion of potassium (renal failure, infections, medications), extracellular shifting of potassium into ECFs (acidosis), cell lysis iii. Signs and symptoms of hyperkalemia include muscle weakness, arrhythmias, bradycardia, hypotension and cardiac arrest. 3. Chloride a. Reference Range: 95 to 105 mEq/L b. Major anion of ECF; follows sodium and contributes to water homeostasis. c. Hypochloremia: i. Low serum chloride ii. May be caused by excessive excretion of chloride however a change in serum chloride is rarely an indicator for a primary medical problem (no real diagnostic significance) d. Hyperchloremia: i. High serum chloride ii. Often seen in hyperchloremic metabolic acidosis from renal disease, severe dehydration or iatrogenic administration of normal saline (NaCL) 4. Carbon Dioxide/Bicarbonate a. Reference Range: 24 to 30 mEq/L b. A measure of bicarbonate concentration (CO2 is either in the free form or complexed as bicarbonate; the complex is more abundant than the free form so one may also hear serum bicarbonate for this measure) c. Acts as a buffer for the body's main acid, CO2 d. Low serum bicarbonate: i. Individual may be experiencing or at risk for metabolic acidosis ii. Signs and symptoms include hyperventilation e. High serum bicarbonate: i. Individual may be experiencing or at risk for metabolic alkalosis ii. Signs and symptoms include hypoventilation 5. Blood Urea Nitrogen (BUN) a. Reference Range: 8 to 18 mg/dL b. Urea nitrogen is an end-product of protein breakdown/metabolism c. BUN is not a measure from the blood (as the name suggests); it is still a measure from the serum. d. Decreased BUN: i. No known pathological consequences e. Increased BUN: i. When used with serum creatinine one may determine if kidney injury due to intrinsic injury or pre-renal injury. A larger ratio (BUN:SCr > 20:1) typically suggests pg. 4 Integrated Laboratory 1 dehydration and pre-renal cause of kidney dysfunction. A ratio of