Levels of which analyte can differ by 50% or more between morning and late afternoon?

Test 4 Notes

Since each blood collection situation is unique, a phlebotomist must have—in addition to the technical skills needed to perform a blood draw—the ability to recognize pre-examination factors and variables that could affect test results and address them, if applicable, to avoid or reduce any negative impact.

Basal state refers to the resting metabolic state of the body early in the morning after fasting (i., going without nutritional support such as food and beverages except water) for approximately 12 hours.

A basal-state specimen is ideal for establishing reference ranges on inpatients because the effects of diet, exercise, and other controllable factors on test results are minimized or eliminated.

Basal state is influenced by physiologic patient variables such as age, gender, and conditions of the body that cannot be eliminated.

Physiologic Variables

1. Age- red blood cell (RBC) and white blood cell (WBC) values are normally higher in newborns than in adults.

• creatinine clearance, a measure of kidney function, is directly related to the age of the patient, which must be factored in when test results are being calculated.
• Hormone levels may also vary by age (e., estrogen and growth hormone [GH] decrease with advanced age).

1. Altitude- RBC counts are a prime example. RBCs carry oxygen. Decreased oxygen levels at higher altitudes cause the body to produce more RBCs to meet the body’s oxygen requirements, the higher the altitude, the greater the increase. Thus, RBC counts and related determinations such as hemoglobin (Hgb) and hematocrit (Hct) have higher reference ranges at higher elevations.

• C-reactive protein and uric acid as well increase with elevation.

• Analytes that decrease in value at increased altitude include urinary creatinine (which in turn affects creatinine clearance tests) and plasma renin.

1. Dehydration Persistent vomiting or diarrhea, causes hemoconcentration, a condition in which blood components that cannot easily leave the bloodstream become concentrated in the smaller plasma volume. Blood components affected include RBCs, enzymes, iron (Fe), calcium (Ca), sodium (Na+), potassium (K+), and coagulation factors.

2. Diet Requiring a patient to fast or follow a special diet up until specimen collection eliminates most dietary influences on testing. The typical fast is 8 to 12 hours depending on the test.

Fasting beyond 12 hours can cause serious health problems, such as electrolyte imbalance and heart rhythm disturbances. Consequently, fasting specimens, especially those requiring a 12-hour fast, should be collected promptly without unreasonable delay.

Ammonia, urea, and uric acid levels may be elevated in patients on high-protein diets. •Cortisol and adrenocorticotropic hormone (ACTH) levels have been shown to increase after drinking beverages containing caffeine. •Glucose (blood sugar) levels increase dramatically with the ingestion of carbohydrates or sugar-laden substances but return to normal within two hours if the patient has normal glucose metabolism. Eating carbohydrates can also increase insulin levels.

Hgb levels can decrease, and electrolyte balance can be altered by drinking excessive amounts of water and other fluids.

Other blood components that exhibit diurnal variation with highest levels occurring in the morning include aldosterone, bilirubin, cortisol, hemoglobin, insulin, iron, potassium, testosterone, and RBCs.

Blood levels of eosinophils, creatinine, glucose, GH, triglycerides, and phosphate are normally lowest in the morning. Diurnal variations can be large. For example, the levels of cortisol, TSH, and iron can differ by 50% or more between morning and late afternoon.

A change of several time zones can affect diurnal rhythm and the tests associated with it. Several days may be required to restore a normal rhythm. Tests influenced by diurnal variation are often ordered as timed tests; it is important to collect them as close to the time indicated as possible.

1. Drug Therapy

Some drugs alter physiologic functions, causing changes in the concentrations of certain blood analytes.

•Chemotherapy drugs can cause a decrease in blood cells, especially WBCs and platelets. •Many drugs are toxic to the liver, as evidenced by increased levels of liver enzymes such as aspartate aminotransaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH), and decreased production of clotting factors. Erythromycin and acetaminophen (e., Tylenol) can increase AST and bilirubin levels and give a false indication of abnormal liver function. Acetaminophen can also be a cause of abnormal liver function. •Opiates such as morphine increase levels of liver and pancreatic enzymes. •Oral contraceptives can affect the results of many tests. For example, they can elevate the erythrocyte sedimentation rate (ESR) and decrease

levels of vitamin B12. •Steroids and diuretics can cause pancreatitis and an increase in amylase and lipase values.

•Thiazide diuretics (blood pressure medications) can elevate calcium and glucose levels and decrease sodium and potassium levels. Other thiazide-type medications that lower blood volume can increase blood levels of nitrogenous waste such as urea, a condition called azotemia.

An acronym for substances that interfere in the testing process is CRUD, which stands for “compounds reacting unfortunately as the desired.”

According to CAP guidelines, drugs that interfere with blood tests should be stopped or avoided 4 to 24 hours prior to obtaining the blood sample for testing.

1. Exercise

Exercise affects several blood components, raising levels of some and lowering levels of others.

The following are examples of the effects of exercise on blood components:

•Arterial pH and PaCO2 levels are reduced by exercise.

•Glucose, creatinine, insulin, lactic acid, and total protein can be elevated by moderate muscular activity.

•Potassium (K+) is released from the cells during exercise, increasing levels in the plasma. Levels generally return to normal after several minutes of rest.

•Skeletal muscle enzyme levels are increased by exercise, with levels of creatine kinase (CK) and LDH remaining elevated for 24 hours or more.

The term icteric means relating to or marked by jaundice and is used to describe serum, plasma, or urine specimens that have an abnormal deep yellow to yellow-brown color due to high bilirubin levels

Point: Although there are other causes, jaundice in a patient may indicate liver inflammation caused by hepatitis B or C virus.

1. Position

Body position before and during blood collection can influence specimen composition. Going from supine (lying down on the back) to an upright sitting or standing position causes blood fluids to filter into the tissues, decreasing plasma volume in an adult up to 10%.

A significant increase in potassium (K+) levels occurs within 30 minutes of standing; this has been attributed to the release of intracellular potassium from muscle.

•A change in position from lying to standing can cause up to a 15% increase in total cholesterol and high-density lipoprotein (HDL) cholesterol results, and 10% to 12% higher triglyceride results.

Patients with congestive heart failure and hepatic disorders may exhibit even more pronounced positional effects.

The National Cholesterol Education Program recommends that lipid profiles be collected in a consistent manner after the patient has been either lying down or sitting quietly for a minimum of five minutes.

•Plasma aldosterone and renin change more slowly but can double within an hour. Consequently, patients are typically required to be recumbent (lying down) for at least 30 minutes prior to aldosterone specimen collection, and plasma renin activity levels require documentation of the patient’s position during collection.

•The RBC count of a patient who has been standing for approximately 15 minutes will be higher than a basal-state RBC count of that patient. The reverse happens when the patient lies down. In fact, the normal physiologic response to a change in position from standing to lying down can cause a condition called postural pseudo anemia (posture- related false anemia), a substantial decrease in hematocrit values due to an increase in plasma that could be mistaken for blood loss or acute anemia. Values return to normal when the patient has been sitting up for a while, as blood fluid moves back into the tissues.

1. Pregnancy

Pregnancy causes physiologic changes in many body systems. Consequently, results of some laboratory tests must be compared with reference ranges established for pregnant populations. For example, increases in body fluid that are normal during pregnancy have a diluting effect on RBCs, leading to lower RBC counts.

Misconception Alert: When asked the following question in the Jones & Bartlett Learning Test Prep: Why do pregnant patients have lower reference ranges for red blood cell (RBC) counts? 26% of the students incorrectly chose “The growing fetus uses up the mother’s iron reserves.” The correct answer is “Increased body fluids result in dilution of the RBCs.” Increased body fluids result in a normal dilution of the RBCs in a pregnant patient. Therefore, the normal RBC reference range for pregnant patients is lower than that of women who are not pregnant. If the patient also has low iron reserves, the RBC count would most likely be lower than the normal range for pregnant patients.

1. Smoking

Some blood components are affected by the nicotine absorbed through smoking.

Acute heat exposure causes interstitial fluid to move into the blood vessels, increasing plasma volume and influencing its composition.

Laboratory temperature and humidity are closely monitored to maintain specimen integrity and ensure equipment functions properly.

Problem Sites

1. Burns, Scars, and Tattoos
2. Damaged Veins sclerosed Thrombosed occluded
3. Edema
4. Hematoma
5. Mastectomy - Lymphedema can cause range-of-motion limitations as well as pain, weakness, and/or stiffness in the affected extremity. When a mastectomy has been performed on both sides or there is no suitable site other than an arm on a mastectomy side, the patient’s physician must be consulted, and written permission to draw from the arm on a mastectomy side obtained from the physician.
6. Obesity To locate the cephalic vein, rotate the patient’s arm medially, so that the hand is prone. In this position, the weight of excess tissue often pulls downward, making the cephalic vein easier to feel and penetrate with a needle.
7. Paralysis An arm that has lost muscle function has also lost the muscle action that helps return blood to the heart. This can result in stagnation of blood flow and increase the chance of vein thrombosis.

Ways to Help Prevent Hemoconcentration During Venipuncture

•Ask the patient to release the fist upon blood flow.

•Choose an appropriate patent vein.

•Do not allow the patient to pump the fist.

•Do not excessively massage the area in locating a vein.

•Do not probe or redirect the needle multiple times in search of a vein.

•Release the tourniquet within 1 minute.

Hemolyzed specimens can result from patient conditions such as hemolytic anemia, liver disease, or a transfusion reaction, but they are more commonly the result of procedural errors in specimen collection or handling that damage the RBCs.

Hemolysis can erroneously elevate certain analytes, especially potassium. (There is 23 times as much potassium in RBCs as in plasma.) Hemolysis also elevates ammonia, catecholamines, CK and other enzymes, iron, magnesium, and phosphate. RBC counts can be decreased by hemolysis. A specimen that is hemolyzed because of procedural error will most likely be rejected for testing and need to be redrawn.

Procedural Errors That Can Cause Specimen Hemolysis

•Drawing blood through a hematoma

•Drawing blood through an IV valve or other VAD

•Failure to wipe away the first drop of capillary blood, which can contain alcohol residue

•Failing to protect specimens from temperature extremes during off- site transportation

•Excess sodium fluoride in underfilled gray-top tubes can result in hemolysis of the specimen.

•Underfilled coagulation tubes do not have the correct blood-to- additive ratio and will produce erroneous results.

Specimen Contamination Specimen contamination is typically inadvertent and generally the result of improper technique or carelessness, such as:

•Allowing alcohol, fingerprints, baby powder, or urine from wet diapers to contaminate newborn screening forms or specimens, leading to specimen rejection.

•Filling tubes in the wrong order of draw. For example, drawing a potassium EDTA tube before a serum or plasma tube for chemistry tests can lead to EDTA contamination of the chemistry tube and cause false hyperkalemia (high potassium) and hypocalcemia (low calcium).

•Getting glove powder or baby powder on blood films (slides) or in capillary specimens, resulting in misinterpretation of results. Calcium- containing powders can affect calcium results.

•Unwittingly dripping perspiration into capillary specimens during collection or any specimen during processing or testing. The salt in sweat, for example, can affect sodium and chloride levels.

•Using the correct antiseptic but not following proper procedure. For example, improperly cleaning blood-culture bottle tops or the collection site, touching the site after it has been prepped (cleansed), or inserting the needle before the antiseptic on the arm or bottle tops is dry. (Traces of the antiseptic in the culture medium can inhibit the growth of bacteria and cause false-negative results.) Performing capillary puncture before the alcohol is dry can cause hemolysis of the specimen and lead to inaccurate results or rejection of the specimen by the laboratory.

•Using the wrong antiseptic to clean the site prior to specimen collection. For example, using alcohol to clean the site can contaminate an ethanol (blood alcohol) specimen. Using povidone–iodine (e., Betadine) to clean a skin-puncture site can contaminate the specimen and cause erroneously high levels of uric acid, phosphate, and potassium.

To troubleshoot failed venipuncture the important steps to remember are stop, assess, and correct.

Collapsed Vein

A vein can collapse despite correct needle position. When a vein collapses, the walls draw together temporarily, shutting off blood flow. This can happen if the vacuum draw of a tube or the pressure created by pulling on a syringe plunger is too much for the vein.

A vein can also collapse if the tourniquet is tied too tightly or too close to the venipuncture site. In this case, blood cannot be replaced as quickly as it is withdrawn, causing the vein to collapse.

In addition, veins sometimes collapse when the tourniquet is removed during the draw. This is often the case in elderly patients, whose veins are fragile and collapse more easily.

1 levels of which analyte typically occur around 08:00 hours?

a b c d

2 of these tests are most affected if the patient is not fasting?

a and protime b and triglycerides c and cardiac enzymes d culture and thyroid profile

b the draw and attempt collection at another site. c the patient with small talk and continue the draw. d the patient to hang in there as you have only one tube left.

9 situation can result in hemoconcentration? a a large tube with a small needle b the tourniquet on for over one minute c the specimen too vigorously d filling a normal-draw tube

10 are in the process of collecting a specimen by venipuncture. You hear a hissing sound, there is a spurt of blood into the tube, and blood flow stops. What has most likely happened?

a vein b went too deep c of tube contents d vacuum escaped

11 test result reference ranges are values for a individuals. b who are ill. c of the same age. d disorders. 12 a venipuncture fails to draw blood and the phlebotomist senses a slight vibration of the needle, this could be a sign that the needle a up against a valve. b a nerve. c a hematoma. d through the vein.

13 arm that is paralyzed a no muscle function. b sensory damage also. c a permanent condition. d the result of a stroke.

14 bariatric phlebotomy chair is designed for individuals who are a. apt to faint. b ill. c. d.

15 AV fistula is most used for a. b access. c. drawing blood. d infusion.

16 situation can hemolyze a specimen?

a a large tube with a 23-gauge butterfly b aspiration of blood with a syringe c transportation of tubes of blood d. All of the above

17 type of therapy can increase bilirubin levels? a. Acetaminophen pills b pressure medications c drugs d contraceptives

18 anemia can be caused by a change in position from standing to lying down. b a blood specimen through an IV valve. c the tourniquet on longer than one minute. d too large of a needle to collect a specimen.

19 clearance is a measure of a metabolism. b function. c function. d activity.

20 that interfere with blood tests should be stopped or avoided for a to 24 hours. b to 12 hours. c to 36 hours. d to 72 hours.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Which analyte test result will be adversely affected by chilling?

What is diurnal variation in phlebotomy?

Which of the following three tests are most affected by hemolysis?

What tests are most affected if the patient is not fasting?