Thursday, March 22, 2012

Why lactate dehydrogenase in Light's criteria?

LDH is an enzyme found in almost all cells.

Tissue injury releases LDH.

If it's level is elevated in the plasma or extracellular fluid, that indicates cell death or cell membrane injury :O

It happens in all cases of exudates.. Inflammation remember?

Hence, LDH can be used to differentiate between transudate & exudate :)


Wednesday, March 21, 2012

Exudate & Transudate

Hello everyone!
Whenever you find fluid in the body which is out of the circulatory system you need to differentiate whether this fluid is an exudate or a transudate (Only if it is in pathologically significant amounts!)

I'll let you know why this is important in a while.. Keep reading.

Exudate vs Transudate
More proteins.
More cells.
Mnemonic: Exudate exudes proteins.

Does not contain large plasma proteins like fibrinogen.
Has a few, if any, cells.
Mnemonic: Transudate is transparent (No proteins)

Clinical significance:
This is important for the diagnosis of the underlying cause..
Exudate occurs when inflammation leads to increased capillary permeability.
Transudate occurs when there are imbalances in hydrostatic and oncotic forces in circulation. There is an intact capillary endothelial barrier which causes ultra-filtration of plasma.

So let's say your pleural fluid is an transudate.
Then your therapy will be diverted to the underlying congestive heart failure, cirrhosis or nephrosis. But if your fluid is an exudate then you have to look for infections, malignancies, empyema, rheumatoid pleuritis, embolism, etc.

We use Light's criteria for deciding whether pleural fluid is transudate or exudate.
An exudate will have:
Pleural fluid [protein] / plasma [protein] > 0.5
Pleural fluid [LDH] / plasma [LDH] > 0.6 or 2/3

We use Serum Albumin Ascites Gradient for finding out the cause of ascites. (The transudate versus exudate wasn't good enough)
SAAG = Albumin in serum - Albumin in ascitic fluid
If SAAG > 1.1 it's portal hypertension.
If SAAG < 1.1 it could be cancer, nephrotic syndrome, cancer, tuberculosis, etc.

That's all!
Hope you got it.. Feel free to ask. I haven't covered all of it.. It's a huuuge topic.
Have a nice day ^_^

Friday, March 2, 2012

Hypersensitivity types mnemonic

Hypersensitivity is a state of altered reactivity in which the body reacts with an exaggerated immune response to what is perceived as a foreign substance.

What if you had no idea which hypersensitivity reaction they are talking about in the exam? Disaster right?

Well.. I got it sorted for you.. Remember, "ACID"

Type I - Anaphylaxis
Type II - Cytotoxic
Type III - Immune complex mediated
Type IV - Delayed type of hypersensitivity

Hypersensitivity types mnemonic

There is another type V Autoimmune disease.. Some people put it in type II though..

Wanna remember the disorders too?
Okay.. here you go..

Type I AAA

Goodpasture's syndrome
Autoimmune hemolytic anemia
Erythroblastosis fetalis

Extrinsic allergic alveolitis (Hypersensitivity pneumonitis)
Arthus reaction
Rheumatoid arthritis
Serum sickness
Systemic lupus erythematosus (SLE)

Contact dermatitis
Mantoux test
Chronic transplant rejection
Multiple sclerosis

Type V GMG

Graves' disease
Myasthenia Gravis

Hope this helps..
Have an amazing year :)


Updated: Image on 25th Oct, 2013.

Wanna reblog? Here's the link to the tumblr post!

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