INTERPRETING CLINICAL LABORATORY DATA

Question 1

Quantitative: data is

Answer 1

Data can be accurately 
measured, but not observed
Examples:
Temperature of 39°C
Respiratory Rate of 22
Pain is a 6 out of 10

Question 2

Qualitative data is

Answer 2

Data can be observed, but not 
accurately measured
Examples:
Fever
Hyperventilation
Wincing in pain

Question 3

NORMAL RANGE

Answer 3

Can vary based on the studied population
 Heart rate for athletes vs. non-athletes
Typically a fixed point
 Normal heart rate is approximately 80 beats/min (bpm)

Question 4

REFERENCE RANGE

Answer 4

Provides a wider range of accepted values
Derived from the mean ± 2 standard deviations
 Heart rate range from 60 to 100 bpm

Question 5

TEMPERATURE FOR NORMAL and reference ranges are

Answer 5

Normal:
 98.6 F or 37 C

Reference range:
 97 to 100.3 F or 36.1 to 37.9 C

Hypothermia: ≤ 96.9 F / 36 C
Hyperthermia: ≥ 100.4 F / 38 C
 Cut-offs above are ‘general’ and may be individualized

Question 6

TEMPERATURE CONVERSIONS

Answer 6

Conversion to Celsius: (Temp. in Fahrenheit minus 32) / 1.8

Conversion to Fahrenheit: (Temp in Celsius x 1.8) + 32

Question 7

BLOOD PRESSURE systolic and diastolic range

Answer 7

Systolic
 Peak pressure in the arteries
Normal is 120, Range (typical) is 100 to 140 mmHg

Diastolic
Lowest arterial pressure
Normal is 80, Range (typical) is 70 to 90 mmHg

Question 8

INTERPRETING BLOOD PRESSURE for Hypotensive, Normotensive and Hypertensive

Answer 8

❖Hypotensive
 Systolic < 100 mmHg or Diastolic < 70 mmHg or both

❖Normotensive:
 Systolic between 100-139 and Diastolic between 70-89

❖Hypertensive:
 Systolic ≥ 140 mmHg or Diastolic ≥ 90 mmHg or both

Question 9

HEART AND LUNGS (Heart Rate range, Bradycardia, Tachycardia, Respiratory range. Oxygen saturation range)

Answer 9

Heart Rate –> Reference Range: 60 to 100 bpm

Bradycardia: HR <60 bpm

Tachycardia: HR >100 bpm

Respiratory Rate: Reference Range: 14 to 18 breaths/min

Oxygen Saturation: O2 Sat or SaO2
Reference Range: 92 to 100% on room air

Question 10

WEIGHT

ABW (Actual Body Weight)

IBW (Ideal Body Weight)

Answer 10

ABW (Actual Body Weight) Wt in Lbs. ÷ 2.2 = wt. in Kg.

IBW (Ideal Body Weight)

Men: 50 + 2.3 (# of inches over 5 ft)

Women: 45.5 + 2.3 (# of inches over 5 ft)

Question 11

SODIUM RANGE IS

Answer 11

(135 TO 146 MEQ/L)

Sodium is predominantly found in the extracellular fluid
Sodium abnormalities are usually a result of changes in water homeostasis
Fluid imbalances can be caused by volume overload (e.g. heart/liver failure) or volume depletion (e.g. vomiting / blood loss)

Question 12

POTASSIUM Range is

Answer 12

(3.4 – 5.2 MEQ/L)

Potassium is predominantly an intracellular cation, all but 2% is located within cells

Required for various enzymatic processes e.g. sodium/potassium ATPase, Krebs cycle

Plays an important role in skeletal and smooth muscle contraction

Hypokalemia: K < 3.4 mEq/L
Typically caused by fluid loss:
Bleeding, diarrhea, diuresis, vomiting
E.g. Stools can contain 40-60 mEq/L of K

Hyperkalemia: K > 5.2 mEq/L
Typically caused by renal dysfunction (decr. clearance)
It May be drug-induced (ACEI/ARB, Potassium-sparing diuretics)

Muscle weakness:
Results from either low levels or high levels of potassium as K helps
to regulate activities of skeletal, cardiac, and smooth muscle cells.

Since K regulates cardiac muscle cells, dysrhythmias can be induced

Question 13

CHLORIDE range is

Answer 13

(98 – 110 MEQ/L)

Accounts for approx. 1/3 of all serum in the extracellular fluid

Is actively filtered via the kidneys, along with Na

Hypo and hyperchloremia occur for reasons similar to those causing hypo and
hypernatremia. Diuretic use, vomiting

Hypochloremia may cause muscle excitability and tremors

Hyperchloremia may cause weakness and lethargy

Question 14

BICARBONATE: HCO3 range is

Answer 14

(24-32 MEQ/L)

Measures the bodies level of carbon dioxide
Is a marker of acid/base balance

Hypobicarbonatemia levels may indicate an acidotic process e.g. metabolic, diabetic ketoacidosis, or an overdose of ethylene, methanol, or salicylates

Hyperbicarbonatemia levels may indicate long term COPD (carbon dioxide retention), or an alkalotic process

Question 15

BLOOD UREA NITROGEN: The BUN range is

Answer 15

(7-23 MG/DL)

The waste product from the production of ammonia by the liver

Healthy kidneys can filter and remove this urea via the urine

Low BUN levels may indicate: Liver disease/damage, malnutrition

High BUN levels may indicate: Renal disease/damage, dehydration, or high protein intake

Question 16

SERUM CREATININE: SCR range is

Answer 16

(0.5-1.1 MG/DL)

SCR is a chemical waste product produced primarily by muscle metabolism
Filtered via the kidneys, similarly to BUN

Low Scr can indicate: Lack of nutrition/muscle mass

High Scr can indicate: Renal disease/damage, excess muscle mass

Question 17

GLUCOSE: GLU range is

Answer 17

(70-100 MG/DL)

Is a source of energy for most cells in the body

Carbohydrates are broken down in the body into glucose

Regulated by insulin and glucagon

Levels <60 mg/dL can induce somnolence and coma

Levels >125 mg/dL indicate impairment and may lead to a diagnosis of
diabetes

Question 18

SERUM CALCIUM: CA range is

Answer 18

(8.4 – 10.4 MG/DL)

Involved in muscle contraction and bone formation

99% is stored in skeleton and teeth

Regulated by vitamin D and parathyroid hormone

40% bound to serum albumin

Question 19

HYPOCALCEMIA: CA < 8.4 MG/DL and HYPERCALCEMIA: CA > 10.4 MG/DL

Answer 19

Causes:
Poor calcium intake and/or Vit. D deficiency
Approx. 500 mg of calcium is removed from the bones/day
Vit. D stimulates calcium absorption
 Hypoparathyroidism: part of a feedback loop that regulates reabsorption of calcium
from bone

S/sx:
 Paraesthesia
 Tetany
 QTc Prolongation/arrhythmias

Causes:
Malignancy due to bone metastases
Hyperparathyroidism
Renal insufficiency

S/sx: “Bones, stones, groans, and psychic moans”
Lytic lesions
 Urinary calculi
 Malaise
N/V
 Mental status changes (confusion, depression)

Question 20

COMPONENTS OF SERUM CALCIUM which contain

Answer 20

Albumin-bound calcium(40%)

Ionized (free) calcium (45%)

Salt-bound calcium(15%)

Question 21

IONIZED CALCIUM

Answer 21

Ionized calcium only fluctuates with changes in the parathyroid hormones and vitamin D levels

Reference ranges:
Children: 4.4 - 6.0 milligrams per deciliter (mg/dL)
Adults: 4.4 - 5.3 mg/dL

Question 22

CORRECTED CALCIUM

Answer 22

Corrected serum Ca calculation: Observed serum Ca + 0.8 (4 – serum albumin)

Examples:
Ca: 8.1 mg/dL, Alb: 1.8 gm/dL
Does this patient need calcium replacement?

Question 23

PHOSPHATE: PO4 range is

Answer 23

(2.4 – 4.4 MG/DL)

Major intracellular anion

Important role in:
 Bone mineralization
 Storage and transfer of energy
 Muscle contraction
 Metabolism of glucose and lipids
 Maintenance of acid-base balance

Question 24

HYPOPHOSPHATEMIA: PO4 < 2.4 MG/DL
HYPERPHOSPHATEMIA: PO4 > 4.4 MG/DL

Answer 24

HYPOPHOSPHATEMIA: PO4 < 2.4 MG/DL

Moderate: 1 - 2.5 mg/dL
Severe: < 1 mg/dL
❖Causes:
Inadequate dietary intake
Hyperparathyroidism (increased excretion)
DKA (diabetic ketoacidosis)
❖S/Sx:
 Muscle weakness/dysfunction
 Mental status changes

HYPERPHOSPHATEMIA: PO4 > 4.4 MG/DL
Common cause:
Renal failure
❖Calcium-Phosphate product
 Ca x PO4 = Calcium-phosphate product
 If a product is > 55 in CKD, precipitation occurs and lytic lesions form

Question 25

MAGNESIUM: MG range is

Answer 25

(1.6 – 2.6 MG/DL) Second most abundant intracellular cation Required for utilization of ATP for energy Important in regulating energy, protein synthesis, neuromuscular transmission, CV tone Located mostly in bone and muscle tissues

Question 26

HYPERMAGNESEMIA: MG > 2.6 MG/DL HYPOMAGNESEMIA: MG < 1.6 MG/DL

Answer 26

HYPERMAGNESEMIA: MG > 2.6 MG/DL Common causes: Excessive magnesium intake or renal failure ❖S/Sx: Sedation, nausea, vomiting, decreased reflexes, and EKG changes HYPOMAGNESEMIA: MG < 1.6 MG/DL Common causes: Vomiting, diarrhea, diuretics Often coincides with hypokalemia: Need to replace magnesium along with potassium ❖S/sx: Nausea, vomiting, and EKG changes

Question 27

LIVER AND GASTROENTEROLOGY TESTS are

Answer 27

``` AST (aspartate aminotransferase) ALT (alanine aminotransferase) ALP (alkaline phosphatase) LD or LDH (lactate dehydrogenase) Bilirubin Albumin Amylase and Lipase INR (international normalized ratio) ```

Question 28

AST/ALT: Range is

Answer 28

0 - 35 IU/L AST/ALT are enzymes found w/in the liver that aid in metabolism of proteins and amino acids Increases may indicate hepatocellular injury (e.g., hepatitis or cirrhosis), as they leak from the liver into the serum Can see ↑AST in other types of cell injury (post-MI), ALT more specific for liver Several medications may increase ALT/AST Statins, TZDs, EtOH

Question 29

ALKALINE PHOSPHATASE: the range is

Answer 29

30–120 U/L ALP is an enzyme that aids in producing proteins within the body  Primarily located in liver and bone, secreted in bile increases may indicate an obstruction (liver/biliary), or bone disease/breakdown (Paget’s disease)

Question 30

LACTATE DEHYDROGENASE: range is

Answer 30

50–150 U/L LD is necessary for the citric acid cycle to produce NADH, pyruvate and thus, energy Present in most tissues (making it nonspecific for liver) Increases may indicate some type of liver dysfunction Almost always increases post-MI within 10-12 hours

Question 31

BILIRUBIN and DIRECT BILIRUBIN range is

Answer 31

Bilirubin 0.1–1 MG/DL; DIRECT: 0–0.2 MG/DL A metabolic byproduct of the lysis of erythrocytes by the reticuloendothelial system ``` Hyperbilirubinemia Pre hepatic (hemolysis) Hepatic (defective removal of bilirubin from blood or conjugation) Posthepatic or cholestatic (obstruction) ``` If total bilirubin increases > 2 mg/dL, jaundice can develop

Question 32

ALBUMIN range is

Answer 32

3.5 – 5 G/DL Most abundant protein in the body Synthesized in the liver Therefore is a marker of true hepatic function 3 major functions: Controlling oncotic pressure in the plasma Transporting amino acids synthesized in the liver to other tissues Transporting poorly soluble ligands

Question 33

AMYLASE and LIPASE range is

Answer 33

AMYLASE (0 – 130 IU/L) LIPASE (0 - 160 IU/L) Enzymes are secreted by the pancreas to breakdown carbs, proteins, and fats Increases after the onset of acute pancreatitis in most patients

Question 34

INR range is

Answer 34

0.8-1.2 Measures the clotting tendency or coagulation properties of the blood Prolonged in those: Receiving warfarin With liver damage

Question 35

COMPLETE BLOOD COUNTS INCLUDE

Answer 35

Hgb Hct WBCs RBCs

Question 36

ERYTHROCYTES (RBCs)

Answer 36

Produced in the bone marrow, released into peripheral blood, circulate for 120 days (60 days in those with CKD) Main function is to carry oxygen from the lungs to the Tissues Anemia occurs when Hgb, Hct, and/or RBCs decrease Causes may be multifactorial e.g. nutritional deficiencies (iron, folate, thiamine), bone marrow alterations, chronic disease

Question 37

HEMOGLOBIN (HGB)

Answer 37

Oxygen carrying compound contained in RBCs

Question 38

HEMATOCRIT (HCT)

Answer 38

Percentage of RBCs in a volume of whole blood

Question 39

PLATELETS (PLTS)

Answer 39

Maintaining the integrity of blood vessels plays a key role in hemostasis and blood clotting Lifespan = 8 – 12 days

Question 40

WHITE BLOOD CELLS PLUS DIFFERENTIAL

Answer 40

WBCs (Leukocytes): ``` Consists of cells of the immune system Include the following types of cells: Neutrophils Bands Lymphocytes Monocytes Eosinophils Basophils ```

Question 41

NEUTROPHILS are

Answer 41

Makeup approx. 60% of total WBC Neutrophils = segs = polys = PMNs = granulocytes Increase in infections, tissue destruction, inflammatory disease, stress, steroids Decrease in cancer, post-chemotherapy, side effects of drugs Absolute neutrophil count (ANC) = (WBC)(% neutrophils) Neutropenia (ANC < 500/mm3) increases risk of infection

Question 42

BANDS are

Answer 42

Bands: Makeup 5% of WBC Immature neutrophils Increase in response to acute infection (left shift = bands >5%)

Question 43

LYMPHOCYTES

Answer 43

Makeup 30% of WBC Recognize foreign substances and initiate the immune response ``` Two types: T lymphocytes (cell-mediated immunity) B lymphocytes (antibody-mediated immunity) ```

Question 44

MONOCYTES are

Answer 44

Make up 7% of WBC Formed in bone marrow, migrate to tissue and mature into macrophages Increased in subacute bacterial endocarditis, malaria, tuberculosis, recovery phase from infections, initial recovery from chemotherapy

Question 45

EOSINOPHILS are

Answer 45

Makeup 3% of WBC Surface receptor for IgG and IgE Involved in hypersensitivity response or any allergic disorder

Question 46

BASOPHILS

Answer 46

Make up <1% of WBC Probably involved in immediate hypersensitivity reactions and delayed allergic reactions May be increase in chronic inflammation and leukemia's

Question 47

METHODS FOR ESTIMATING RENAL FUNCTION

Answer 47

❖Cockcroft and Gault ``` ❖Others do exist, but will not be reviewed here: MDRD Modifications in Diet and Renal Disease Salazar Corcoran (for obese patients) Urinary creatinine (24-hr creatinine) Jelliffe Schwartz ```

Question 48

COCKCROFT AND GAULT

Answer 48

CrCl= [ (140-age) x IBW / 72 x SCr ] x0.85 (women) CrCl = Creatinine clearance in mL/min/1.73 m2 Use IBW unless patient’s ABW weight is < than their IBW, then use ABW • Weight = kg • SCr = mg/dL

Question 49

USES FOR COCKCROFT AND GAULT

Answer 49

Estimation of creatinine clearance, not the direct calculation of creatinine clearance or GFR (glomerular filtration rate) Currently C-G equation is the only validated method of renal function that can be utilized for drug dosing. Validated in most patient populations: Men Women Those with comorbidities

Question 50

ISSUES SURROUNDING THE USE OF C-G

Answer 50

Unstable kidney function: Defined as a change in Scr by ≥ 50% in 24 hours C-G greatly over-estimates CrCl No good method in this situation currently exists Use best clinical judgment when evaluating the renal function for drug dosing ``` Elderly patients (≥ 65 years in age): Some institutions will round up Scr to 1, if the actual value is <1 For this class, you should use given Scr, and do not round up to 1 ```