Clinical Chemistry Flashcards
What should you use to palpate the area to feel for a vein when performing a venipuncture?
Tip of index finger on non-dominant hand
What is serum?
A plasma specimen that clotting factors are added to and anything that doesn’t clot is serum
What is in the plasma of blood?
92% Water
7% Proteins = albumin, globulins, fibrinogen, regulatory proteins
1% Other Solutes = electrolytes, nutrients, respiratory gases, and waste products
What can cause a high value for potassium?
Hemolysis of blood sample
How are individual electrolyte ions measured?
With ion selective electrodes
Where in the blood can electrolytes be found?
Serum or plasma
What are ion selective electrodes?
A transducer that converts the activity of a specific ion dissolved in solution into an electrical potential which can be measured by voltemeter
It contains a thin membrane across which only the intended ion can be transported
The transport of ions from high concentrations to low concentrations through selective binding sites within the membrane creates a potential difference resulting in an electrical potential
What is the control for ion selective electrodes?
External reference electrode
What is the solution for ion selective electrodes?
serum or plasma
What is spectrophotometry?
Measures change in light absorbance at certain wave lengths
What is an Enzyme Linked Immunoabsorbent Assay (ELISA)?
Detects serum antibody or antigen
What is a critical value?
any test result that may required rapid clinical attention to avert significant patient morbidity or mortality
Lab will notify provider immediately
What is a Comprehensive Metabolic Panel (CMP)?
Basic Metabolic Panel (BMP) + Calcium + Liver Function Studies (LFTs)
What is in a Basic Metabolic Panel?
Serum Sodium Serum Potassium Chloride CO2 - blood gas Blood Urea Nitrogen (BUN) Creatinine Glucose - blood sugar
What are other names for a basic metabolic panel?
CHEM-7
SMA7
What does Serum Sodium reflect?
Changes in water balance rather than sodium balance
What are the functions of serum sodium?
Maintain osmotic pressure of extracellular fluid
Acid-base Balance
Neuromuscular Function
Absorption of glucose
What are the causes of Hyponatremia?
Hypervolemic hyponatremia (Na is diluted) = CHF
Hypovolemic hyponatremia = dehydration (overall volume depletion)
What are the causes of Hypernatremia?
Hypervolemic hypernatremia = CHF
Hypovolemic Hypernatremia (Na is concentrated) = Dehydration (free water deficit)
What is the first symptom of Hyponatremia?
weakness
What are the symptoms when Na levels RAPIDLY DROP from 140 to 130 mEg/L?
Thirst Impaired Taste Anorexia Dyspnea on exertion Fatigue Dulled sensorium
What are the symptoms when Na levels drop from 130 to 120 mEq/L?
Severe GI symptoms
vomiting
Abdominal cramps
What are the symptoms when Na levels drop below 115 mEq/L?
Confusion Lethargy Muscle twitching Convulsions Coma Stupor (brain stem herniation)
What occurs when Na levels are between 110-115 mEq/L?
Likely to cause severe and sometimes irreversible neurologic damage like cerebral edema
How do you treat hyponatremia?
Treat the underlying cause!
If patient is dehydrated = hydrate them
If patient is fluid overloaded = diurese
What is IV normal saline (IVNS)?
0.9% NaCl
Called “Isotonic saline” but is actually inc. Na conc. and volume expanding
Treats dehydration
What is IV1/2NS?
0.45% NaCl
Closer to isotonic
Maintenance fluid
What is Lactated Ringers (LR)?
Contains NaCl, sodium lactate, KCl, CaCl in water
Used in trauma and surgery
What is hypertonic saline?
3% NaCl
Used for sudden precipitous drops in sodium like in a marathon runner
What are the symptoms of Hypernatremia?
Dry mucous membranes Thirst Agitation Restlessness Hyperreflexia Mania Convulsions
What is the treatment for Hypernatremia?
Administer “free water” in the form of dextrose 5% in water
Cannot administer free water because it will cause hemolysis, so you must include dextrose
What are the dangers of correcting sodium too rapidly?
1) Central pontine myelinolysis = confusion, encephalopathy, lethargy, weakness, and paralysis
2) Cerebral edema
3) Brain stem herniation
Last two are associated with Hyponatremia only
What is Central pontine myelinolysis?
Destruction of myelin covering nerve cells in the brainstem
What are the normal levels of sodium?
135-145 mEq/L
What are the normal levels of K?
3.5 - 5.0 mEq/L
What are the functions of serum potassium?
Maintain intracellular osmolality
Acid base balance
Transmission of nerve impulses
Essential to skeletal, cardiac, and smooth muscle function
What mechanisms regulate potassium?
Insulin
Kidneys
How does insulin regulate potassium?
Ingested potassium rapidly enters portal circulation and stimulates the pancreas to release insulin
Elevated insulin stimulates cells to allow glucose to enter and potassium follows into the cells
How do the kidneys regulate potassium?
Excess potassium is excreted by the kidneys and eliminated in the urine
What causes Hypokalemia?
Inadequate intake
Excessive losses = GI, renal, or skin burns
Redistribution into cells
What causes hyperkalemia?
Decreased renal eliminationMOST COMMON
Excessively rapid administration
Movement of potassium from inside the cell to outside the cell like when there is trauma
What are the signs and symptoms of Hypokalemia?
Weakness Muscle Cramps Paralysis EKG changes Cardiac arrhythmias = Afib Paralytic ileus
What are the signs and symptoms of Hyperkalemia?
Weakness Muscle Cramps Paresthesias EKG changes Cardiac arrhythmias Intestinal cramping
What is the normal level of Chloride in the blood?
98-106 mEq/L
What is the function of chloride?
Maintains electrical neutrality by binding to positively charged ions
What is Chloride an indicator of?
Hydration status
What are the normal levels of Carbon dioxide in the blood?
23-30 mEq/L
What is most CO2 in the form of in the serum?
Bicarbonate
What does CO2 indicate?
pH status
What is the anion gap?
The difference between the primary measured cations and the primary measured anions in serum
(Na+ + K+) - (Cl- + HCO3-)
What is a normal anion gap level?
8-16 mEq/L