COMMON LABORATORY VALUES STEP HA N IE ZIELIN SKI, C P N P , D N P - - PowerPoint PPT Presentation

STEP HA N IE ZIELIN SKI, C P N P , D N P

COMMON LABORATORY VALUES

COMMON LABORATORY VALUES

• Laboratory tests are an integral part of every day

practice within health care.

• Lab work can help assess and diagnose patients with

both acute and chronic illness.

COMMON LABORATORY TESTS

• Complete Blood Count with Differential
• Basic Metabolic Profile
• Iron Studies (TIBC, Ferritin)
• Thyroid Studies (TSH, Free t4)
• Vitamin D
• Lipid Panel

COMMON LABORATORY TESTS

• Complete Blood Count with Differential aka “CBC with

Diff”

• Components of a CBC with differential:
• Total red blood cell count (RBC)
• Hemoglobin (Hgb)
• Hematocrit (Hct)
• Mean Corpuscular volume (MCV)
• Red blood cell distribution width (RDW)
• Total white blood cell count (WBC)
• A count (%) of each type of white blood cell (Neutrophils,

Lymphocytes, Monocytes, Eosinophils, Basophils)

• Platelet count

(T he Ma yo C linic , 2016; Up to Da te , 2016)

COMMON LABORATORY TESTS

• What does each finding mean?
• Total red blood cell count (RBC)- The count of the

number of circulating red blood cells in 1 mm3 of peripheral venous blood.

• Hemoglobin (Hgb)- The measure of the amount of Hgb

in the blood. Hgb constitutes over 90% of red blood cells.

COMMON LABORATORY TESTS

• A decrease in Hgb concentration means the patient is

anemic.

• Anemia can be due to iron/B12/folate deficiency, blood

disorders or other underlying pathology.

• And increase in Hgb concentration means the patient is

polycythemic.

• Polycythemia can result from a large number of causes, including

cancer, lung disease, heart defects and other underlying

• pathologies. Smoking and many lung conditions can cause an

elevated Hgb due to chronic hypoxia.

COMMON LABORATORY TESTS

• Hematocrit- The measure of the percentage of the total

blood volume that is made up by the red blood cells.

• Mean corpuscular volume (MCV)- a measure of the

average size of a red blood cell. The MCV is important in classifying anemias:

• Normal MCV = normocytic anemia
• Decreased MCV = microcytic anemia
• Increased MCV = macrocytic anemia

COMMON LABORATORY TESTS

• Red blood cell distribution width- An indication of the

variation of the red blood cell size (anisocytosis).

• In general an elevated RDW (more variation in the size of the

RBC’s) is associated with anemias with various deficiencies such as iron, B12 or folate deficiencies.

COMMON LABORATORY TESTS

• What does each type of anemia mean?

Macrocytic Anemia-

• In adults, common causes of macrocytic anemia are:
• Medications (ex: Zidovuidine, Hydroxyurea), folate deficiency,

abnormal RBC maturation (Ex: Leukemia), alcohol abuse, liver disease and hypothyroidism

• In children common causes of macrocytic anemia are:
• Medications (anticonvulsants, Zidovudine and immunosuppresents),

Vitamin B12 and folate deficiencies, liver disease and hypothyroidism

COMMON LABORATORY TESTS

• What does each type of anemia mean?

Microcytic Anemia-

• In adults, common causes of microcytic anemia are:
• Reduced iron availability (iron deficiency, copper deficiency), Alpha
• r beta thalassemia and anemia of inflammation (chronic disease).
• In children common causes of microcytic anemia are:
• Iron deficiency and thalassemia

COMMON LABORATORY TESTS

• What does each type of anemia mean?

Normocytic Anemia-

• In adults, common causes of normocytic anemia are:
• Systemic disorders, chronic renal disease
• In children common causes of normocytic anemia are:
• Hemolytic disease, blood loss, infection and medication

COMMON LABORATORY TESTS

• Testing for iron deficiency:

Total Iron Binding Capacity (TIBC)- Will be elevated when a patient is anemic. Ferritin- The cellular storage protein for iron. Iron deficiency results in a low ferritin level. Iron deficiency is the only clinical situation in which extremely low values

• f serum ferritin are seen

COMMON LABORATORY TESTS

• White Blood Cells-
• Lymphocytes- Comprise about 30-40% of circulating

white blood cells.

• Atypical and an elevated number of lymphocytes can often be

seen following viral infections.

• Other causes of atypical lymphocytes or lymphocytosis can be

lymphoma or leukemia.

• If a patient has lymphocytosis in addition to thrombocytopenia,

neutropenia or anemia, this is concerning for malignancy. Patient should be referred immediately for hematology/oncology evaluation.

COMMON LABORATORY TESTS

• Neutrophils- 40-60% of circulating white blood cells.
• Neutrophils mature in the following order:

Myeloblast -> promyelocyte -> myelocyte -> metamyelocyte -> band -> mature neutrophil.

CBC/blood smear results with any cells seen that are less mature than a myelocyte are almost always associated with hematological

• malignancy. This warrants immediate hematology/oncology

referral. An increased number of bands is called a “left shift” and is often associated with infection.

COMMON LABORATORY TESTS

• A low level of neutrophils is Neutropenia. A low level of

neutrophils can increase the risk of infection.

• Neutropenia can be caused by malignancy, immunosuppression
• r be idiopathic.
• An elevated Neutrophil count (Neutrophilia) is most

commonly seen with infections, stress, smoking and after exercise.

COMMON LABORATORY TESTS

• Basophils- Comprise <1% of total WBC. An elevated basophil

count is most commonly associated with myeloproliferative disorders, hypersensitivity or inflammatory reactions, hypothyroidism, and certain infections.

• Eosinophils- Normally present in small numbers (< 5% of

WBC’s). Elevated level can indicate allergic state or parasitic

• infection. Less commonly it can indicate a malignancy.
• Monocytes- The largest of the WBC’s. Elevated monocyte

level is most commonly associated with infections, autoimmune disorders, malignancy and blood disorders.

COMMON LABORATORY TESTS

Platelets

• Thrombocytopenia- (low platelet count)- Most commonly

seen due to medications (antibiotics, antiepileptics), infection, blood disorders and liver disease.

• The presence of a very high platelet count, extremely large

platelets, and/or megakaryocyte fragments is abnormal and

• ften associated with an underlying malignancy.

COMMON LABORATORY TESTS

• Basic Metabolic Profile
• Comprised of:
• Sodium (Na)
• Potassium (K)
• Chloride (Cl)
• Carbon Dioxide Content (CO2)
• Blood Urea Nitrogen (BUN)
• Serum Creatinine (Cr)
• Serum Glucose (Glu)
• Total Calcium (Calcium)

COMMON LABORATORY TESTS

• Sodium (Na)
• Hyponatremia- Sodium is low. This is not a common finding and is
• ften associated with heart failure, burns, malnutrition and severe

diarrhea.

• Hypernatremia- Sodium is elevated. This is commonly associated

with three main issues:

• Un-replaced water loss- diarrhea/vomiting, excessive sweating,

diabetes insipidus, diabetic ketoacidosis

• water loss into cells- usually transient, typically induced by

severe exercise or electroshock induced seizures.

• sodium overload- salt poisoning, hypertonic saline

administration

COMMON LABORATORY TESTS

Potassium (K) Hypokalemia- A low level of potassium. Hypokalemia is most commonly caused by the use of diuretics, severe burns, Cushing’s syndrome, acute GI illness, hyper-aldosteronism, and renal disease.

COMMON LABORATORY TESTS

Potassium (K) Hyperkalemia- Elevated potassium, caused by three main mechanisms:

• Excessive increase in potassium intake
• Trans-cellular movement of intracellular potassium into

the extracellular space

• Decreased renal excretion of potassium

COMMON LABORATORY TESTS

Potassium (K)

• Excessive increase in potassium intake- typically caused

by a high potassium containing medication or IV fluid.

• Trans-cellular movement of intracellular potassium into

the extracellular space- metabolic acidosis or breakdown

• f normal tissue or rapid cell lysis causing potassium to be

released into the extracellular space; ex. Renal failure, tumor lysis, rhabdomyolysis.

• Decreased renal excretion of potassium- Kidney disease

COMMON LABORATORY TESTS

Potassium (K) *Remember: In children, psuedohyperkalemia can occur due to the small needle size which can cause the blood sample to hemolyze resulting in a falsely elevated potassium level.

COMMON LABORATORY TESTS

• Chloride
• Elevated Chloride Level- Dehydration, excessive salt intake,

kidney disease, hyperparathyroidism

• Low Chloride Level- occurs when there is too much water in

the body (ex: syndrome of inappropriate antidiuretic hormone), Addison’s disease, Metabolic Alkalosis, heart failure.

COMMON LABORATORY TESTS

• Carbon Dioxide Content (CO2)aka “bicarb”
• Bicarbonate is an electrolyte, a negatively charged ion that is used

by the body to help maintain the body's acid-base (pH) balance.

• Acidosis and alkalosis describe the abnormal conditions that result

from an imbalance in the pH of the blood caused by an excess of acid or alkali (base).

• Any disease or condition that affects the lungs, kidneys,

metabolism, or breathing has the potential to cause acidosis or alkalosis.

COMMON LABORATORY TESTS

• Carbon Dioxide Content (CO2)aka “bicarb”
• Elevated CO2 can be caused by: Dehydration, Chronic diarrhea,

kidney disease, Addison’s disease, Diabetic Ketoacidosis

• Low CO2 can be caused by: severe prolonged vomiting, lung

disease (ex: COPD), heart failure, kidney disease

COMMON LABORATORY TESTS

• Blood Urea Nitrogen (BUN)
• Urea is formed in the liver as the end product of protein

metabolism and is transported to the kidneys for excretion.

• Nearly all renal diseases can cause an inadequate excretion of

urea, which causes the blood concentration to rise above normal (thus an elevated BUN).

• The BUN is interpreted in conjunction with the creatinine test –

these tests are referred to as “renal function studies”.

COMMON LABORATORY TESTS

• Serum Creatinine

Creatinine is a catabolic product of creatine phosphate used in skeletal muscle contraction. Creatinine, as with blood urea nitrogen, is excreted entirely by the kidneys and blood levels are therefore proportional to renal excretory function. An elevated Creatinine level is related to kidney disease or decreased kidney function.

COMMON LABORATORY TESTS

• Glucose- This is one of the most commonly ordered blood

tests.

• Hyperglycemia (Elevated Glucose)- most commonly caused

by underlying diabetes, but can also be a result of significant stress on the body or sepsis.

• Hypoglycemia (Low glucose)- Can be caused by underlying

diabetes, long term or excessive fasting, underlying neurogenic disorder or severe illness/sepsis.

COMMON LABORATORY TESTS

• Serum Calcium
• The total serum calcium is a measure of both
• Free (ionized) calcium
• Protein bound (usually to albumin) calcium
• Calcium level is most influenced by parathyroid hormone (PTH),

vitamin D, the calcium ion, and phosphate.

Hypercalcemia (elevated calcium)- primary hyperparathyroidism and malignancy are the most common causes. Hypocalcemia (low calcium)- Disorders of PTH and Vitamin D are the most common causes.

COMMON LABORATORY TESTS

• Thyroid Studies
• The Thyroid gland produced T3 and T4. The thyroid gland is stimulated

to produce these by Thyroid Stimulating Hormone (TSH) that is released by the pituitary gland.

• A high TSH is often accompanied by a low Free T4. This is because the body

will typically increase the TSH to help increase a low T4 level. This is typically indicative of hypothyroidism.

• If TSH and T4 are both low, this is indicative of a pituitary problem.
• Serum TSH low and T3/T4 are elevated, this is indicative of

hyperthyroidism.

COMMON LABORATORY TESTS

Vitamin D

• Low Vitamin D- most commonly caused by decreased

intake or absorption, reduced sun exposure.

• High Vitamin D- Very rare, typically seen when a

patient has ingested a high amount of vitamin d (dose error or “fad” diet with high doses of supplements)

COMMON LABORATORY TESTS

Thyroid Studies

The Thyroid gland produced T3 and T4. The thyroid gland is stimulated to produce these by Thyroid Stimulating Hormone (TSH) that is released by the pituitary gland.

• A high TSH is often accompanied by a low Free T4. This is because the body

will typically increase the TSH to help increase a low T4 level. This is typically indicative of hypothyroidism.

• If TSH and T4 are both low, this is indicative of a pituitary problem.
• Serum TSH low and T3/T4 are elevated, this is indicative of

hyperthyroidism.

COMMON LABORATORY TESTS

Lipid Panel A lipid panel is comprised of: Cholesterol- Total cholesterol Triglycerides- Fat in the blood from meals or made by liver in response to sugars and

• fats. This can be elevated if the patient ate a high fat meal before the blood draw.

HDL (High density lipoprotein)- the “good” cholesterol, removes excess cholesterol and moves it to the liver LDL (Low density lipoprotein)- The “bad” cholesterol, deposits excess cholesterol in the walls of blood vessels Non HDL- Total cholesterol minus the HDL Chol/HDL Ratio – Total cholesterol divided by HDL.

REFERENCES

Up to Date (2016). Lab results retrieved from uptodate.com Accessed February 20th, 2016. The Mayo Clinic (2016). Diseases and Conditions retrieved from themayoclinic.org accessed February 20th, 2016