EXAM2_WORKSHOP2_Serum_Chemistry_Profile Flashcards Preview

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Flashcards in EXAM2_WORKSHOP2_Serum_Chemistry_Profile Deck (15)
1

PLASMA PROTEINS
three classes based on solubility in saline:

1. Fibrinogen
2. Albumin
3. Globulins

2

Albumin
Where made?
HL?
amount produced/day

Plasma Serum protein (most abundant)
-Made in Liver
HL ~16 days
12g/day (25% hepatic protein synthesis)


1. oncotic pressure
2. maintains plasma volume (fluid between tissue & IS)
3. Carrier protein (FA or Ca)
-can also act as reservoir

3

Important notes of Serum chemistry profile

1. not used to make a diagnosis

2. best if used over a long time (months, years) to follow patients response to treatment

3. helps support ideas from history and physical exam

4

If analyte follows Gaussian Distribution:

Analyte values use the MEAN +- 2 SD.

-2.5% healthy will have values above these limits
-2.5% healthy will have values below these limits

-

5

If analyte follows Skewed (non-Gaussian) distribution:

Values for a sample population ranked by numerical value and references are established by dropping the highest 2.5% and lowest 2.5% of the falues

6

Critical Difference (CD)
What is it?
Why is it important?

Determines if differences between two values in a patient are statistically significant

-Smallest variability (low CD coefficients %)
(Na, Cl, Ca, Proteins, Albumin)

-Intermediate variability (Glucose, cholesterol, phosphate)

-Large Variability (highest CD coefficient %)
(uric acid, urea, enzymes, Triglycerides)

7

Calculate Critical Difference:

IF |a-b| > CD*(a+b)/2 then the difference is statistically significant

8

6 Examples of molecules that albumin transports in the blood

Ca,
steroid hormones,
FFA's,
Tryptophan,
Aspirin,
Bilirubin

9

Oncotic pressure
What is it?
What is it proportional to?
how much attributed to albumin?

-force that pulls water back into the capillaries to maintain normal blood volume

OP proportional to concentration of protein molecules in blood

-80% of oncotic pressure caused by Albumin
20% by globulins

10

Hypoalbuminemia (what albumin shift?)

Edema

body shifts albumin from Interstitial fluid to vascular system

Edema results in net fluid accumulation in interstitium

11

Filtration pressure
Absorbing Pressure

Hydrostatic pressure in blood - oncotic pressure (back into blood)= filtration pressure
- have low net outflow (on arterial side)

Absorbing Pressure (AP)
Hydrostatic pressure in vein- oncotic pressure in Interstitial space= AP

HP>OP = net outflow in artery
HP

12

What happens when albumin is low?

Low oncotic pressure (hard to get fluid back into vein)
-FP is increased and more fluid moves out into interstitium

Filtration "out" pressure is greater than absorption "in" pressure (respective of blood volume)

RESULTS IN EDEMA

13

Serum calcium

Albumin bound calcium: When does it decrease?

Free Ca (bioavailable ca)

Do Free Ca levels vary? what if albumin-Ca varies?

Total serum Ca = (albumin bound Ca + free Ca)

Albumin-bound Ca: can decrease when albumin low, or affinity changes (acidosis)

Free "bioavailable" calcium in plasma is tightly regulated and remains constant regardless of albumin-bound Ca

14

Acidosis affects what Ca levels?

Acidosis decreases albumin binding Ca and Overall Ca levels but not the bio-available Ca levels (stay constant)

15

How do you calculate Albumin-Adjusted Serum Calcium?

(4 - patient's albumin) X 0.8 + patients total serum Ca= Albumin-Adjusted Serum Calcium

4 is average normal albumin
0.8 average Ca/albumin

1. find missing albumin
2. find missing Ca
3. amount Ca if patient was not hypoalbuminemic