INTERPRETING CLINICAL LABORATORY DATA Flashcards
Quantitative: data is
Data can be accurately measured, but not observed Examples: Temperature of 39°C Respiratory Rate of 22 Pain is a 6 out of 10
Qualitative data is
Data can be observed, but not accurately measured Examples: Fever Hyperventilation Wincing in pain
NORMAL RANGE
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)
REFERENCE RANGE
Provides a wider range of accepted values
Derived from the mean ± 2 standard deviations
Heart rate range from 60 to 100 bpm
TEMPERATURE FOR NORMAL and reference ranges are
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
TEMPERATURE CONVERSIONS
Conversion to Celsius: (Temp. in Fahrenheit minus 32) / 1.8
Conversion to Fahrenheit: (Temp in Celsius x 1.8) + 32
BLOOD PRESSURE systolic and diastolic range
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
INTERPRETING BLOOD PRESSURE for Hypotensive, Normotensive and Hypertensive
❖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
HEART AND LUNGS (Heart Rate range, Bradycardia, Tachycardia, Respiratory range. Oxygen saturation range)
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
WEIGHT
ABW (Actual Body Weight)
IBW (Ideal Body Weight)
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)
SODIUM RANGE IS
(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)
POTASSIUM Range is
(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
CHLORIDE range is
(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
BICARBONATE: HCO3 range is
(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
BLOOD UREA NITROGEN: The BUN range is
(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
SERUM CREATININE: SCR range is
(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
GLUCOSE: GLU range is
(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
SERUM CALCIUM: CA range is
(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
HYPOCALCEMIA: CA < 8.4 MG/DL and HYPERCALCEMIA: CA > 10.4 MG/DL
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)
COMPONENTS OF SERUM CALCIUM which contain
Albumin-bound calcium(40%)
Ionized (free) calcium (45%)
Salt-bound calcium(15%)
IONIZED CALCIUM
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
CORRECTED CALCIUM
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?
PHOSPHATE: PO4 range is
(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
HYPOPHOSPHATEMIA: PO4 < 2.4 MG/DL
HYPERPHOSPHATEMIA: PO4 > 4.4 MG/DL
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
MAGNESIUM: MG range is
(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
HYPERMAGNESEMIA: MG > 2.6 MG/DL
HYPOMAGNESEMIA: MG < 1.6 MG/DL
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
LIVER AND GASTROENTEROLOGY TESTS are
AST (aspartate aminotransferase) ALT (alanine aminotransferase) ALP (alkaline phosphatase) LD or LDH (lactate dehydrogenase) Bilirubin Albumin Amylase and Lipase INR (international normalized ratio)
AST/ALT: Range is
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
ALKALINE PHOSPHATASE: the range is
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)
LACTATE DEHYDROGENASE: range is
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
BILIRUBIN and DIRECT BILIRUBIN range is
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
ALBUMIN range is
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
AMYLASE and LIPASE range is
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
INR range is
0.8-1.2
Measures the clotting tendency or coagulation properties of the blood
Prolonged in those:
Receiving warfarin
With liver damage
COMPLETE BLOOD COUNTS INCLUDE
Hgb
Hct
WBCs
RBCs
ERYTHROCYTES (RBCs)
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
HEMOGLOBIN (HGB)
Oxygen carrying compound contained in RBCs
HEMATOCRIT (HCT)
Percentage of RBCs in a volume of whole blood
PLATELETS (PLTS)
Maintaining the integrity of blood vessels plays a key role in hemostasis and blood clotting
Lifespan = 8 – 12 days
WHITE BLOOD CELLS PLUS DIFFERENTIAL
WBCs (Leukocytes):
Consists of cells of the immune system Include the following types of cells: Neutrophils Bands Lymphocytes Monocytes Eosinophils Basophils
NEUTROPHILS are
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
BANDS are
Bands:
Makeup 5% of WBC
Immature neutrophils
Increase in response to acute infection
(left shift = bands >5%)
LYMPHOCYTES
Makeup 30% of WBC
Recognize foreign substances and initiate the immune response
Two types: T lymphocytes (cell-mediated immunity) B lymphocytes (antibody-mediated immunity)
MONOCYTES are
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
EOSINOPHILS are
Makeup 3% of WBC
Surface receptor for IgG and IgE
Involved in hypersensitivity response or any allergic disorder
BASOPHILS
Make up <1% of WBC
Probably involved in immediate hypersensitivity reactions and delayed allergic reactions
May be increase in chronic inflammation and leukemia’s
METHODS FOR ESTIMATING RENAL FUNCTION
❖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
COCKCROFT AND GAULT
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
USES FOR COCKCROFT AND GAULT
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
ISSUES SURROUNDING THE USE OF C-G
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
