Physiological Variables that Influence Lab Test Results Flashcards
PREANALYTICAL CONSIDERATIONS
IN PHLEBOTOMY
- Preanalytical- before analysis
- Begins when a test is ordered and ends when testing begins
- Basal state: resting metabolic state of the body early morning after approximately 12 hours fasting
- Basal state is influenced by a number of physiologic variables such as age, gender, and conditions of the body that cannot be
eliminated
Physiological Variables that Influence
Laboratory Test Results
-Age
-Jaundice
-Altitude
-Intramuscular Injection
-Dehydration
-Position
-Diurnal Variation
-Pregnancy
-Drug Therapy
-Smoking
-Exercise
-Stress
-Gender
-Temperature & Humidity
AGE
* RBC and WBC values ____ in newborns
* Kidney function (creatinine clearance) ____ with age
higher
decrease
ALTITUDE
* Red blood cell (RBC) counts elevated at _____ altitude
higher
DEHYDRATION
* Hemoconcentration
_____
RBCs, enzymes, iron (Fe), calcium (Ca), sodium (Na)
DIET
LIPIDS
ELECTROLYTES
AMMONIA
GLUCOSE
Tests that requires FASTING:
- FBS
- Glucose tolerance test
- Triglycerides & lipid panel
- Gastrin
- Insulin
- Aldosterone & renin
- Electrolytes
DIURNAL/CIRCADIAN VARIATIONS
Melatonin levels are affected by light
●Renin and thyroid-stimulating hormone (TSH)
Cortisol levels
Exhibit diurnal variation with highest levels in the morning
DRUG THERAPY
● Chemotherapy drugs can cause a decrease in blood cells, especially
WBCs and platelets
● Many drugs are toxic to the liver
● increase levels of liver enzymes:
○ Aspartate aminotransaminase (AST)
○ Alkaline phosphatase (ALP)
○ Lactate dehydrogenase (LDH)
● Steroids and diuretics: increase amylase and lipase
FEVER
○ Increases hormones insulin and glucagon
○ increases cortisol
GENDER
RBC, hemoglobin (Hgb), andhematocrit (Hct)
normal values are
higher for males than for females
EXERCISE
● Arterial pH and PCO2 levels are reduced
● Glucose can be elevated by moderate muscular activity
● Potassium (K+) is increased in the plasma
● Skeletal muscle enzymes creatine kinase (CK) and lactate dehydrogenase
(LDH) are increased by exercise
INTRAMUSCULAR INJECTION
increases levels of creatine kinase (CK) and the skeletal muscle
fraction of LDH
JAUNDICE
● icteric : deep yellow to yellow-brown color of serum or plasma
● interferes with chemistry tests based on color reactions
BODY POSITION
● from supine to an upright sitting or standing position
causes blood fluids to filter into the tissues, decreasing
plasma volume
● Increased: protein in nature or bound to protein—such as
aldosterone, bilirubin, blood cells, calcium, cholesterol, iron,
protein, and renin
● increase in potassium (K) levels
PREGNANCY
● lower RBC counts
SMOKING
● Increased cholesterol, cortisol, glucose, growth hormone, and
triglyceride levels and WBC counts
● Chronic smoking : decreased pulmonary function and increased
RBC counts and hemoglobin levels
● Smoking can also affect the body’s immune response, lowering the
conc. of immunoglobulins
STRESS
● Increases in WBC counts
● Decrease serum iron levels
● Increase adrenocorticotropic hormone(ACTH), catecholamine, and
cortisol levels
TEMPERATURE and HUMIDITY
hemoconcentration
increase with ingestion of fatty foods
➢Lipids
UREA increase in patients on high-protein diets
Ammonia,
altered by drinking excessive water
➢Electrolytes
e increase with the ingestion of carbohydrates
➢Glucose
Increase at night and decrease during day
Melatonin levels are affected by light
Peak levels in the predawn hours of the morning during sleep
Renin and thyroid-stimulating hormone (TSH)
Peak: later in the morning, around 8:00am
Cortisol levels
Exhibit diurnal variation with highest levels in the morning:
aldosterone, bilirubin, cortisol, hemoglobin, insulin, iron, potassium,
testosterone, and RBCs
increase amylase and lipase
Steroids and diuretics
Chemotherapy drugs can cause a ____in blood cells, especially
_______
decrease
WBCs and platelets
increase levels of liver enzymes:
○ Aspartate aminotransaminase (AST)
○ Alkaline phosphatase (ALP)
○ Lactate dehydrogenase (LDH)
Skeletal muscle enzymes creatine kinase (CK) and lactate dehydrogenase
(LDH) are _____by exercise
increased
Potassium (K+) is ______ in the plasma
increased
Glucose can be elevated by _____
moderate muscular activity
BODY POSITION
Increased: protein in nature or bound to protein—such as
aldosterone, bilirubin, blood cells, calcium, cholesterol, iron,
protein, and renin
Arterial pH and PCO2 levels _________
are reduced
increase in potassium (K) levels
BODY POSITION
lower RBC counts
PREGNANCY
Increased ___________ and ________ levels and WBC counts
cholesterol, cortisol, glucose, growth hormone, and
triglyceride
decreased pulmonary function and increased
RBC counts and hemoglobin levels
Chronic smoking
Smoking can also affect the body’s immune response, lowering the
_____
conc. of immunoglobulins
Increase adrenocorticotropic hormone(ACTH), catecholamine, and
cortisol levels
STRESS
Resting metabolic state of the body early morning after approximately 12 hours fasting
BASAL STATE IN PREANALYTICAL CONSIDERATIONS
IN PHLEBOTOMY
influenced by a number of physiologic variables such as age, gender, and conditions of the body that cannot be
eliminated
PREANALYTICAL CONSIDERATIONS
IN PHLEBOTOMY
