Lecture 6 Flashcards
Test performed on blood and other body fluids
Blood collection:
Venous or capillary
Serum most often used (SST)
Could also include plasma (heparinized) or whole blood
Test performed on blood and other body fluids Arterial
For blood gas measurements – Heparinized sample
Place on ice and analyze immediately
Serum is commonly used for
most clinical chemistry tests
Depending on the analyzer and methods, serum, plasma and/or whole blood may be used
Be familiar with all blood collection tubes and anticoagulants
Chemistry – SST, red top, green, grey, royal blue
What should you not do:
Avoid collecting blood from - an arm with IV, or collecting above an IV line
Specimen must be free from hemolysis - Falsely elevated results – K+, LD, AST, Mg+, Iron, Vitamin B12, Folate
Timing of specimen – fasting, random, 2hr PC, antibiotic testing
Avoid delay in delivery to the lab or testing – test within one hour of collection
Refrigerate the serum at 40C if testing is delayed
Analyte
Chemical substance/test for analysis
Profiles
– Group of tests performed to determine the condition of patients, function of organs or systems
Profiles/Panel include – Kidney/renal, liver/hepatic, cardiac, lipid, thyroid
Units of measurement – SI units
Analytes – millimoles per liter – mmol/L
Enzymes – units per liter – U/L
Therapeutic Drugs – often in mg/dL
Electrolytes – ions in body fluids
Measurement of electrolytes include:
Na+, K+, Cl-, HCO3-
Cations and Anions
Electrolyte balance within the body is important in maintaining fluid and acid-base balance
What are ELECTROLYTES?
Substance when dissolved in solution separates into ions; is able to carry an electrical current
CATION - positively charged electrolyte ANION - negatively charged electrolyte # Cations must = # Anions for homeostatsis to exist in each fluid compartment Commonly measured in mmol/liter
INTRACELLULAR FLUID (ICF) - 63%
Inside cell Most of body fluid here - 63% weight Decreased in elderly POTASSIUM MAGNESIUM PHOSPHOROUS
EXTRACELLULAR FLUID (ECF) - 37%
Outside cell
Intravascular fluid - within blood vessels (5%)
Interstitial fluid - between cells, blood vessels (15%)
Transcellular fluid - cerebrospinal, pericardial , synovial
SODIUM CALCIUM
CHLORIDE
BICARBONATE
Significance of Electrolytes
Blood volume Blood pressure Blood pH Nerve impulses Muscular activity Buffer body fluids and control movement of fluids between intra and extracellular departments
ADH (Antidiuretic Hormone)
Made in hypothalamus; water conservation hormone
Acts on renal collecting tubule to regulate reabsorption or elimination of water
If blood volume decreases, then ADH is released water is reabsorbed by kidney. Urine output will be lower but concentration will be increased.
ALDOSTERONE RENIN
Produced by adrenal cortex
Acts on renal distal convoluted tubule
Regulates water reabsorption by increasing sodium uptake into the blood
Renin - Released by kidneys in response to decreased blood volume which impacts blood pressure
Sodium Functions
Transmission of nerve impulses
Responsible for osmolarity of vascular fluids
Regulation of body fluid levels
Assists with regulation of acid-base balance by combining with Cl or HCO3 to regulate the balance