Clinical Lab Tests- Dr. Heeter

Critical Value Definition

lab value outside of reference range, so far out that immediate action must be taken

Reference Range Definition

range of accepted normal values for a given test

What is the difference between a false negative and false positive?

• false positive is when you are negative, but lab shows your positive

• false negative is when you are positive, but lab shows your negative

Differentiate between sensitivity and specificity.

• sensitivity- ability of test to be positive if they have the disease

• specificity- is it negative, when it needs to be negative

Think: sensitivity goes w/+ and specificity goes w/-

What are some sources of error in the lab?

• collection of specimen

  • Ex: drug test peeing in the cup

• analysis of specimen

  • Ex: the machines aren’t calibrated right

• technical/clerical errors

  • Ex: a lab worker messes up

7 components of the Basic Metabolic panel (BMP) (Chem-7):

1. sodium

2. potassium

3. chloride

4. bicarbonate

5. Blood urea nitrogen (BUN)

6. serum creatinine

7. blood glucose

Which of the following is NOT a component of the basic metabolic panel?

a. chloride

b. serum creatinine

c. bicarbonate

d. albumin

d. (albumin is part of the complete metabolic panel, not basic)

A Chem-8 panel has what additional component, in addition to the 7 that are in a Chem-7 panel?

Calcium

The Chemistry Panel Tree contains the 7 values from the _______.

a. BMP

b. CMP

c. Chem-8

a

What value is missing from the following chemistry panel “tree”?

K

Reference range for Sodium (mEq/L)

135-145 mEq/L

Reference range for Magnesium (mEq/L)

1.3-2.2 mEq/L

Reference range for Potassium (mEq/L)

3.5-5.0 mEq/L

Reference range for Chloride (mEq/L)

97- 110 mEq/L

Reference range for Bicarbonate (mEq/L)

22-26 mEq/L

Reference range for Blood Urea Nitrogen (BUN) (mg/dL)

8-20 mg/dL

Reference range for Serum Creatinine (mg/dL)

0.7-1.3 mg/dL

Reference range for glucose in the fasting state (mg/dL)

65-109 mg/dL

Reference range for calcium (mg/dL)

8.6- 10.3 mg/dL

Reference range for Phosphate (mg/dL)

2.5-4.5 mg/dL

Is a sodium level of 140 mEq/L normal?

yes

Is a serum creatine level of 0.6 mg/dL normal?

no- low

Is a magnesium level of 3.0 mEq/L normal?

no- high

Usually things that cause ___________ are conditions or things that increase total body water. For example, polydipsia, hyperglycemia.

Hyponatremia

A patient comes into the office complaining of sweating, diarrhea, and always feeling thirsty. Lab work was done, and it was seen that the patient’s sodium levels were 177 mEq/L. What does this patient most likely have?

hypernatremia

A patient with high potassium levels has _______________.

hyperkalemia

A patient taking diuretics and insulin should watch their potassium levels because of the risk of _______________.

hypokalemia

What levels need to be corrected for a patient with hyperglycemia?

Sodium

With chloride, metabolic alkalosis can cause:

hypochloremia

With chloride, metabolic acidosis can cause:

hyperchloremia

Decreased levels of bicarbonate result from metabolic __________ and respiratory ___________.

Use the words: acidosis or alkalosis

• metabolic acidosis

• respiratory alkalosis

Increased levels of bicarbonate result from metabolic __________ and respiratory ___________.

Use the words: acidosis or alkalosis

• metabolic alkalosis

• respiratory acidosis

If our kidneys are not working properly, will Serum Creatinine increase or decrease?

Increase

What are some things that can cause an increase in Blood urea nitrogen?

• dehydration

• renal insufficiency (kidneys not working)

• increased urea

What are some things that can cause a decrease in Blood Urea nitrogen?

• malnourishment (starving)

• profound liver damage (can’t make urea)

Which of the following is not a reason that can cause blood urea nitrogen to increase?

a. dehydration

b. malnourishment

c. kidneys not working

d. increased urea

b

GI losses, like Gastric Bypass Surgery, can cause magnesium levels to _____________ and cause _______________.

Magnesium levels decrease, causes hypomagnesemia

Chronic alcohol abuse can lead to:

a. hypomagnesemia

b. hypermagnesemia

a

Usually, renal insufficiency combined with over-replacement does what to magnesium levels?

a. lowers

b. raises

b - those processes cause hypermagnesemia

If I had impaired PTH production and a vitamin D deficiency, I would most likely have ______________.

hypocalcemia

Mailgnancy and primary hyperparathyroidism combined with renal issues usually causes what abnormal lab value?

hypercalcemia

For what laboratory value MUST we correct because it is largely protein bound?

Calcium

What is the equation for correcting calcium?

Measured Ca + [ 0.8 x (4- albumin)]

Hypophosphatemia and Hyperphosphatemia are tied to an increase or decrease in what?

Vitamin D (also Phosphate)

Renal Insufficiency and increased intake of Vitamin D can lead to _________________.

hyperphosphatemia

Which of the following does NOT cause hypophosphatemia?

a. increased renal excretion

b. intracellular shifting

c. decreased phosphate intake

d. increased vitamin D intake

d

Any diabetic medication can lead to _____glycemia.

hypoglycemia

What are some of the ways hyperglycemia can occur?

• Diabetes

• drugs

  • steroids, thiazides, epi

• excessive sugar intake

Which of the following transaminases are more specific towards liver cells?

a. ALT

b. AST

a

About ____ U/L is the max AST and ALT values.

50

Critical Values of Alk Phos usually indicate what 2 conditions?

1. cholestasis (no bile)

2. bone disorders

Total bilirubin is the sum of __________ and ___________ bilirubin.

sum of direct and indirect bilirubin

What are the 4 main components of CBC that also make up a CBC “cross”

• WBCs

• Hgb

• Hct

• Platelets

What is the male reference range for Hgb?

13.0-18.0 gm/dL

What is the female reference range for Hgb?

12.0-16.0 gm/dL

Usually if Hgb values are below 12-13, what condition do you have?

anemia

Leukocytosis can be caused by:

• infection!

• disease!

• drugs

  • corticosteroids!!!!

• stress

Reminder: leukocytosis is when your body has too many WBCs

Leukopenia can be caused by:

• aging

• diseases

  • HIV, anemia

• drugs

  • chemo drugs

  • sulfonamides

Reminder: Leukopenia is where your body does not have enough WBCs

What is the equation for calculating Absolute Neutrophil Count (ANC)?

ANC= WBC x total neutrophil % ( or bands+segs)

Why do we not want low neutrophil count?

• neutropenia is bad

  • risk of infection

Platelets are a major component of the ____________ cascade.

clotting

Thrombocytosis can be caused by:

• inflammation

• trauma

• cirrhosis

• splenectomy

• iron-def anemia

Thrombocytopenia can be caused by:

• HIT

  • heparin induced thrombocytopenia

Other causes said not to memorize

Which of the following is not a cause of leukocytosis?

a. stress

b. infection

c. aging

d. corticosteroids

c

Which of the following is a cause of thrombocytopenia?

a. inflammation

b. heparin

c. trauma

d. cirrhosis

b

Hemoglobin indicates the _________ carrying capacity of blood.

oxygen

Hematocrit indicates the number of _______s.

RBCs

If you have an increased Mean Corpuscular Volume (MCV) you have ____________ RBCs.

a. macrocytic

b. microcytic

a

If you have a decreased Mean Corpuscular Volume (MCV) you have ____________ RBCs.

a. macrocytic

b. microcytic

b

What type of anemia deals with the destruction of RBC?

a. chronic disease anemia

b. aplastic

c. hemolytic

d. iron-deficiency

c

What type of anemia deals with bone marrow unable to produce RBC?

a. chronic disease anemia

b. aplastic

c. hemolytic

d. iron-deficiency

b

What type of anemia deals with the inability to produce RBC or efficient RBCs?

a. chronic disease anemia

b. aplastic

c. hemolytic

d. iron-deficiency

d (no iron= no RBCs)

Name a few examples of chronic diseases that can cause anemia:

• Crohn’s

• Lupus

• cancer

• RA

• HIV

• hepatitis

• CKD

A squamous epithelial value of ≤___ indicates a clean catch of urine.

5

TSH is managed by ___________ feedback.

a. positive

b. negative

b

High TSH = ______thyroid

a. hypo

b. hyper

hypothyroid

Low TSH = ______thyroid

a. hypo

b. hyper

hyperthyroid

What are the primary markers for diabetes?

Hemoglobin A1c