Calculations Flashcards
How do you convert % normal saline to g/L?
% is g/100mL
Therefore x10 to get g/L
Estimated ECF of a 70kg person?
14L
Formula for Fractional Excretion of Phosphate
(Urine PO4 x Plasma Cr)/ (Plasma PO4 x Urine Cr)
What is clearance of a drug (explanation)?
The clearance of a drug is the volume of plasma from which the drug is completely removed per unit time
Clearance of a drug =
Rate of elimination / Plasma concentration
Formula for Elimination Rate Constant (Kd) based on half life
Kd = 0.693/ half life
Calculation of Anion Gap and Reference Interval
(Na + K) - (Cl + HCO3)
Reference interval: 10-20
Based on Clinipath values
Formula for Reference Change Value
RCV = 2.77* √(CVa^2+CVi^2)
2.77 = k * √2
where k is 1.96
What is meant by an index of individuality <0.6
Subject based reference values more suitable
e.g. Creatinine, ALT
What is mean by an Index of Individuality >1.4
Use population based intervals
Diagnostic Odds Ratio Formula
DOR = (TP/FN)/(FP/TN)
Impact of nephrotic syndrome on lipids
- increase TC
- increase LDL-C
- increase TG
- HDL usually normal or reduced
How to calculate pre-test odds
Pre-test odds = pretest probability /(1-pretest probability)
Formula for creatinine clearance (mL/min)
= Urine Cr (mmol/L) X Urine flow rate (ml/min)
/
Plasma Cr (mmol/L)
How to calculate post test odds
Post test odds = pretest probability X LR
