Reference Equations

% transferrin saturation/UIBC/TIBC

% saturation = (serum Fe/TIBC) * 100

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UIBC = unsat ibc = TIBC - serum Fe

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TIBC = serum Fe + UIBC

unconjugated (indirect) bilirubin

indirect bili = total bili - direct bili (conj)

LDL/Friedewald eqn/non-HDL

LDL = total chol - HDL - (TG/5)

VLDL = TG/5

TG < 400 mg/dL ! → if so, must do direct measurement ie electrophoresis

A/G ratio

albumin / globulin ratio = albumin / (total protein - albumin)

if high → kidney dz, dehydration

timed urine calculations

?Creatinine clearance = urine Cr * flow (vol/time) / plasma Cr

creatinine clearance calc

Beer’s law

A = ebc

A = absorbance

e = constant

b = pathway length

c = concentration

absorbance at given T%

A = 2 - log10(%T)

…

osmolality

osm = 2Na + glc/18 + BUN/2.8

may be 1.86 Na (calculate both!)

anion gap

AG = Na - Cl - HCO3

or

= (Na+K) - Cl - HCO3

> 12 = metabolic acidosis

PiF2?

corrected wbc ct when >10 nrbc present

corr wbc = (total cell*100) / (nrb+100)

manual hemacytometer counts

= (total cells)(dilution factor*10) / total squares counted

manual cell (body fluids)

= (#cells)(DF) / (#squares counted)(depth 0.1)

estimating manual cell count

#cells *10% + #cells

then x100

MCV

Hct / RBC *10

MCH

Hb / RBC * 10

MCHC

Hb / Hct *100

Hct

RBC * MCV / 10

absolute cell counts given the relative value

total wbc * _% of relative value

screening for Ag neg units

units needed / x = % neg Ag frequency / 100

ex) want 3 units of E- and K-

0.7×0.9 = 0.63

3/x = 63/100 → x = 4.8 → 5 units needed to screen

if blood type involved …

Kleihauer Betke

number vials of RhIG = % fetal blood * 50 / 30

• if decimal >5 → round up + 1 vial

• if <5 → round down + 1 vial