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CCP S2 > 223 Laboratory and Diagnostic Medicine > Flashcards

223 Laboratory and Diagnostic Medicine Flashcards

1
Q

Purpose of labs

A

Diagnosis, monitoring, screening, research

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2
Q

What is included in a CBC

A

Rbc, wbc, platelets, Hct, Hgb

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3
Q

Relevance of Hct and normal range

A

% of formed elements in VBG, not specific. Low cells or high plasma.
(F) 0.36-0.47
(M) 0.4-0.52

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4
Q

Relevance and normal value of Hgb

A

Protein responsible for carrying O2 (and CO2)

(F) 120-160g/L
(M) 140-180g/L

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5
Q

Relevance and normal values of WBC

A

Total does not differentiate.

Low (leukopenia)- certain anemias, vitamin deficiencies, sepsis

High (leukocytosis)- inflammation, infection, stress of trauma, malignancy, CVS conditions, steroids

Leukopenia <
4,000-11,000 /microL
>Leukocytosis

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6
Q

What is on the white count differential

A

“Never let monkeys eat bananas”
Neutrophils, lymphocytes, monocytes, eosinophils, basophils

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7
Q

Neutrophils: function and relevance

A

“First wave” attack via phagocytosis

Elevation should prompt investigation for BACTERIAL infection

Normal 40-60% of total WBCs

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8
Q

What is a left shift and why is relevant?

A

A “left shift” is when there is an abundance of band cells (immature neutrophils). Think left shift on the timeline of maturity. In bacterial infection (but not other stress), % band cells will be elevated

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9
Q

Lymphocytes: rôle and function

A

B cells must be primed by antigen to produce antibodies (immunoglobulins)

T cells secrete cytokines to attract other immune cells and or become cytotoxic and kill infected/abnormal cells

NK just attack without prejudice (no priming)

Elevated % should prompt for investigation of VIRAL infection

Normal is 22-44% of total WBC. Differential provides total, not breakdown of B, T, NK

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10
Q

Role and function of monocytes

A

“2nd wave attack” ID and phagocytize bacteria, similar to neutrophils but made faster and last longer. Monocytes become macrophages when they pass into tissue and get larger.
Normal is 3-9% of total WBCs

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11
Q

Role and function of eosinophils

A

ID, seek, destroy via
Increase inflammation by causing production of proinflammatories (prostaglandins, cytokines, leukotrienes)

Increase most often indicates parasitic infection, atopic allergic reaction (asthma, dermatitis, etc) or certain cancers

Steroids, certain conditions (cushings), and bacteremia drop eosinophil count

Normal 1-6% of total WBCs

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12
Q

Role and function of basophils

A

Antibodies on surface, primed for IgE, Contain heparin and histamine

Particularly elevated during allergic reaction and infections of insects such as ticks

Normal is 0-2% of total WBCs

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13
Q

What is on Chem-7 and normal values

A

Aka metabolic panel
1. Na+ 135-145mmol/L
2. K+ 3.5-5.0mmol/L
3. Cl- 98-106mmol/L
4. HCO3- 22-28mmol/L
5. Urea (BUN) 3-7mmol/L
6. Creatinine (f) 55-100
(m) 80-115micromol/L
7. GFR 90-120mL/min/1.73^2
8. Glucose 3-6mmol/L

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14
Q

What is urea

A

Measured as BUN

Product of protein catabolism
May be caused by decreased renal function, consumption of high-protein diet, or high-protein catabolism state (exp. Burns or crush), therefore not reliable indicator of kidney function

Elevated BUN, but normal creatine may indicate upper GI bleed or pre-renal AKI

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15
Q

What is creatinine

A

Waste product from muscle metabolism (creatine, storehouse for energy). Not reabsorbed in tubules.
More reliable indicator of kidney function

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16
Q

BUN:creatine ratio

A

Urea- significant % reabsorbed at tubules.
Creatine is not reabsorbed.

Low perfusion= slower filtration rate and thus more urea being reabsorbed causing disproportionate increase in BUN to creatinine.

Normal is 10:1 to 20:1

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17
Q

What is GFR

A

Measure of overall filtration efficiency, not possible to directly measure. Used to trend chronic disorders and to calculate appropriate fluids/electrolyte tx.

eGFR= creatinine clearance
Compares amount of creatinine excreted in urine with amount in blood over 24hrs

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18
Q

What is on extended lytes panel

A

Mg2+ important for ATP production and other functions. 70% in bones, 30% in serum. Cleared in loop of henle (watch when loop diuretics use).

PO4- Important for ATP production

iCa2+ = unbound/active dispersed in body fluid. Other bound to proteins (ie. albumin) and other molecules (citrate, lactate, phosphate, sulfate)

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19
Q

What is on LFT panel

A

Enzymes- indicate injury NOT function
- Asparate aminotransferase (AST)
- Alanine aminotransferase (ALT) slightly more specific than AST because found in fewer organs
- alkaline phosphates (ALP) used to dx common bile duct obstruction
- gamma-glutamyl transferase (GGT) in conjunction with ALP, used to dx hepatic and biliary disease
- Amylase used to assess pancreatic insufficiency/damage, bile duct obstructions and head trauma
-Lipase more specific than amylase in dx of pancreatic disease, prone to elevation in bile duct obstruction or disease

FUNCTION- produced by liver
- Albumin 40g/L, large plasma protein causing oncotic effect. Binds and deactivates lots of Rx
- Bilirubin (total) by-product of Hgb breakdown, biliary tract obstruction, RBC hemolysis.
- conjugated/ direct bilirubin able to be excreted
Other:
Protein C, protein S, PT, aPTT, INR, glucose

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20
Q

What is on coagulation panel

A

INR, aPTT, fibrinogen, d-dimer, platelets

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21
Q

What is INR

A

International normalized ratio. Normalizing index of PT (rate of conversion of prothrombin to thrombin, representing function of EXTRINSIC pathway)

Normal is 1.1-3.0, therapeutic target is 2.0-3.0

May be elevated in liver disease, warfarin tx
May be decreased in low levels of VitK, DIC or after massive transfusion

22
Q

What is aPTT

A

Activated partial thromboplastin time
Indicates health of INTRINSIC and COMMON pathways. Measured when heparin is used.

Normal is 25-40sec, therapeutic target is 60-90sec

Elevated: hemophilia A or B, von Willebrand disease, DIC

23
Q

What is fibrinogen/factor I

A

Part of common pathway, thrombin cleaves fibrinogen into fibrin

24
Q

What is d-dimer

A

Fragment of clog breakdown, may indicate clotting issue, but not specific.

High: DVT, PE, DIC, CVA, COVID-19
False +: old, smoking, obese, pregnancy, sx, trauma, infection, heart, disease, RA

25
Q

What is on cardiac panel and why order it

A

hs/Troponin (I, T, C), CK-MB, CK, BNP and ANP

ACS, HF, valve problems, post-sx, arrhythmia, -carditis, dissection.

Troponin leak may also be from renal problem (not clearing troponin) or SAH (excessive release of norepi from cardiac sympathetic nerves causes LV systolic dysfunction, cardiogenic shock, pulmonary edema)

26
Q

What is in urinalysis panel

A

Colour, clarity, odour
Specific gravity (high is dark and concentrated)
pH
Protein (nephron problems)
Glucose
Nitrites (indicates UTI, bacterial enzyme converts nitrate to nitrite)
Leukocytes
Ketones

27
Q

Name 6 things to check before reviewing lab/dx studies

A

Pt name and ID #, type of sample taken, location of sample, date of test, time of test, supporting data

28
Q

Define precision

A

Every time a particular lab test is performed, the value will be the same.
High precision= tightly packed values. Does not reflect how well the measurements compare with the true value

29
Q

Define accuracy

A

Measure of the likelihood that an average of a set of test values will be the same as the individual values in the set. Or if the value measured conforms with the true value

30
Q

Define specificity

A

The ability of a certain test to indicate whether a person does NOT have a certain disease

31
Q

Define sensitivity

A

The ability of a certain test to indicate whether a person has a certain disease

32
Q

Define “normal range”

A

Range of values encompassing the results that 95% of healthy people would have for the particular test

33
Q

Define quantitative

A

A quantitative test indicates the exact amount

34
Q

Define qualitative

A

A qualitative test confirms presence/positive or absence/negative, does not identify specific level

35
Q

Indications for urinalysis

A

Reduction in GFR, unexplained albuminuria, or suspected kidney disease

36
Q

What are the three components of urinalysis

A

Gross/macroscopic, dipstick, microscopic

37
Q

What is macroscopic urine evaluation

A

Light or dark, colour, clarity/turbidity, odour

38
Q

What is microscopic urinanalysis

A

Evaluates urine sediment which includes cellular elements (RBCs, WBCs- neutrophils and eosinophils, epithelial cells from urinary tract), casts, crystals, microorganisms, and urinary lipids.

Sample is centrifuged and supernatant poured out, leaving pellet to be resuspended and gently agitated.

39
Q

Name the colours urine can be and common causes

A

Red/brown- hematuria, hemoglobinuria, myoglobinuria, Rx (rifampin, phenytoin, hydroxycobalamin), food (beets, rhubarb, senna), dyes, acute intermittent porphyria

White- phosphate, crystals, chyluria, PROPOFOL

Pink- methylene blue, propofol, amitryptiline, UTI

Black- hemoglobinuria, myoglobinuria, Melanuria

Purple- bacteria from urinary catheter, methylene blue + hydroxycobalamin

40
Q

What causes turbidity in urine

A

Infection, crystals, chyluria (rare condition, lymph leaks into kidneys), or contamination from genital secretions

41
Q

What causes urine odour

A

Ammonia from bacteria, ketones, other rare diseases

42
Q

What is on a urine toxicology screening test

A

Alcohol, amphetamine
Barbiturates, BZs
cocaine
Heroin
Ketamine
Marijuana, methadone
Opiates
PCP

43
Q

Explain the human chorionic gonadotropin (hCG) urine test

A

hCG is made by placenta, urine hCG concentration is much lower than serum and require higher level to detect. Serum test can detect as early as 6 days after ovulation, but typically 8-10 days after ovulation.

urine test is qualititative positive/negative pregnancy.

Can also screen for birth defects (quantitative) by the amount that hCG goes up early in pregnancy.

hCG may also be made by certain tumours, especially from egg/sperm, uterine, or testicles.

44
Q

Microscopic urinanalysis abnormalities

A

RBCs- hematuria- kidney stones, malignancy, glomerular disease

WBCs- neurtrophils commonly associated with bacteriuria, interstitial nephritis, renal TB, nephrolithiasis
Eosinophils commonly associated with acute interstitial nephritis

Epithelial cells= contamination by genital secretions

Casts and crystals

45
Q

Distinguish between -emia and -osis

A

-emia is a state of being (pH)
-osis is a process that is occurring

46
Q

Discuss the effects of albumin on anion gap

A

Albumin is the most prevalent unmeasured anion. Normal/standard is 40g/L, use if unmeasured. When albumin is measured, for every 10 points dropped from standard, add 3 to anion gap.

47
Q

How do you calculate anion gap

A

AG= (na+) - [(Cl-) + (HCO3-)] + albumin compensation

Normal is 8-12 (10 +-2)

48
Q

Define KULT as it pertains to evaluation of metabolic acidosis

A

AGMA causes Ketones, Uremia, Lactate, Toxins

49
Q

Lost the causes of NAGMA

A

GI losses- diarrhe, pancreatic or biliary fistula
Hyperchloremia
Renal tubular necrosis (loss of bicarb leads to acidosis)

50
Q

List the causes of respiratory acidosis OR alkalosis

A

CNS or cardiopulmonary

51
Q

List the causes of metabolic alkalosis

A

Cl- sensitive
- volume depleted, cells contracted
- loss of H+ (vomiting)
- responsive to tx

Cl- resistant
- H+ gone intracellular (HypoK, bicarb admin)
-retaining hco3- (renal)
- Tumor/infection stimulating aldosterone which stimulates HCO3- réabsorption

CCP S2 (19 decks)

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