1-Electrolytes and Water Homeostasis

Intracellular fluid

2/3 of total body water

-inside of cells of every kind

Extracellular fluid

1/3 total body water

-80%: interstitial and intravascular fluid

-20%:blood plasma

Blood colloidal osmotic pressure

helps keep water in blood vessels with the help of albumin

What initiates the RAAS

-incr sympathetic tone

-decr pressure

-decr sodium

Know RAAS steps

What is a colligative property?

property that depends on the # of particles in the solution

What are the 4 colligative properties?

1. osmotic pressure

2. boiling pt elevation

3. freezing pt depression

4. vapor pressure lowering

What colligative property does the osmometer use?

Freezing pt depression

Osmolality Formula

Posm =2Na + Glucose/18 + BUN/2.8

Osmolal Gap formula?

OG= measure -calculated osmolality

What can cause a high osmal gap?

-presence of other osmotically active substances

EX: Lactic acis, Keto acids, alcohols, ethylene glycol

Major electrolytes

sodium, potassium, chloride, and total CO2

What are electrolytes?

conduct an electrical current in solution

Normal range for Na+

135-145 mmol/L

What roles does Na+ have in the body?

H2O homeostasis and osmotic pressure

Sodium is the major _____cation.

extracellular

What method measures Na+?

ISE

Normal range for K+

3.5-5.5 mmol/L

Potassium is the major ____cation

intracellular

Why is hemolysis unacceptable for K+?

ruptured RBC’s will falsely elevate K+

What method measures K+?

ISE with a valinomycin tip

Normal range for chloride (Cl-)

98-109 mmol/L

Chloride is the most abundant ___in the ___fluid.

most abundant anion in extracellular fluid

What method measures Cl-?

Coulometric-amperometric titration

Normal range for CO2

22-28 mmol/L

Total CO2 formula

Total CO2 = CO2 + HCO3-

-bicarb is majority

Normal range for Mg2+

1.5-2.4 mg/dL

What role does Mg play in the body?

-activates 300+ enzymes

-affects permeability and electric properties of membranes

What complex is made to measure Mg2+

Calmagite @ 532 nm

Can Mg assay handle hemolysis

No, Mg is higher inside cells

-hemolysis=false elevation

Anion Gap formula

AGap = (Na+ + K+) - (Cl- + HCO3-)

normal :8-16mmol/L

Where would you see an increased AGAP? (MUDPILES CAT)

What analytes make the AGAP increase?

1 or more unmeasured anions

Where would you see a decreased AGAP?

-RARE

-instrument issue #1

-multiple myeloma

-hyponatremia

Iron metabolism

Total iron refers to Fe3+ bound to ___

transferrin

Total iron has diurnal variation, which sample is best?

morning

What preanalytical error should be avoided with total iron

hemolysis since colorimetric method is used

Ferritin

stores iron inside cells

Testing for ferritin helps asses___

iron storage

Transferrin

transports iron

Why do we test for transferrin

to monitor nutritional status

TIBC

measures body’s ability to bind iron

TIBC reflects ___levels

transferrin

A transferrin test ___measures its levels; TIBC ___measures transferrin.

Directly; Indirectly

IDA

-decr: serum iron, ferritin, %saturation

-incr: TIBC

Hemochromatosis

-incr: ser iron, %saturation, ferritin

-decr: TIBC

in the body, Zinc helps ____

enzymatically

Deficiency in Zinc will cause

-failure of growth

-impaired wound healing

-impair immunity

-mental

-parenteral nutiriotn

Copper is a cofactor for ___enzymes

oxidase

Menke’s syndrome

deficiency in copper

Wilson’s disease

copper toxicity

What key lab finding points to Wilsons disease?

decr ceruloplasmin

What will be incr in Wilsons

urine copper output

What role does Manganese Mn2+ have in the body

-metabolism in connective tissue

-physical growth

-reproductive function

Chromium binds to___

transferrin

List water soluble vitamins

-vit B

-vit C

List fat soluble vitamins

-vit A, D, E, K

B1 is also called___

thiamine

Def in B1 leads to

Beriberi syndrome-peripheral nerve damage

B3 is also called___

Niacin

Def in B3 leads to

Pellagra

B6 is also called___

pyridoxine

*Def in B6 leads to

def is rare and only happen in malabsorption syndromes

B7 is also called ____

Biotin

high levels of B7 can interfere with

immunoassays

B9 is also called

folate

B9 is important for

-RBC formation

-cell growth

B9 is crucial in ___

pregnany

Def in B9 leads to ___ and ___

-megaloblastic anemmia

-neural tube defects

(sometimes spina bifida)

B12 is also called____

cobalamin

Def in B12 leads to___and___

-pernicious anemia

-neurological defects

What is required for B12 absorption?

intrinstic factor

What role does vit C have in the body?

-forms blood vessels, cartilage, muscle, collagen in bones

-vital for wound healing

-antioxdant

Vit C ___in many assays since it is a ___substance

interferes; reducing

What role does Vit D play in the body

calcium absorption and bone metabolism

Def in Vit D

Rickets