Introduction Flashcards
What is positive predicitve value?
Porbability disease is present if the test is positive
eg same as sensitivity - TP rate /TP+FP rates
What is negative predictive value?
If test negative, chance disease is absent
TN/TN + FN rates
When is NPV more powerful?
Less common conditions
Increases with sensitivity
What is likelihood ratio
The probability of a finding in patients with disease/probabulty of the same finding in those without the disease
How to calculate Likelihood ratio in Coronary art disease where dysphaiga is reported in 4% of people with CAD
dysphagia reported in 20% of those with other causes of chest pain
4/20 = 0.2
Test for acute pancreatitis
Amylase
Most useful test in HF
BNP
Lab test most useful for diagnosis of Prostate cancer w bone mets
PSA
What MCV is Iron DA?
mICROCYTIC
wHAT CONDITION OUT OF hEP b, GALLSTONES, PAGETS DISEASe, bone metastases and renal failure is most liekly to have raised ALP AND GGT?
Gallstones - P for pipes therefore blocks bile and damages liver -> GGT
What condition do you find raised APTT and normal PT
Haemophilia A
Why does haemophilia A have normal PT and prolonged APTT
Both measure common,
PT measures extrinsic and APTT measures intrinsic pathways
both factor VIII and IX form part of intrinsic clotting pathways, so deficiencies eg haemophilia A+B -> deficincies in APTT reading
What condition do you find low Na and high K in out of d+V, addisons, heavy alcohol use, DKA, hyperaldosteronism
Addisons disease
Causses low aldosterone -> low Na and high potassium
Function of aldosterone
Increases BP by increasing water retention by increasing sodium release into blood
When can LFTs be skewed
Liver fialure
Heart failure due to oedema congesting the liver
