Read on Twitter
Anyone want to learn the basics of bloods with me? Reading a great book & had fun making this thread about...
BLOOD TESTS: WHAT ARE WE MEASURING??!
See thread
BLOOD TESTS: WHAT ARE WE MEASURING??!
See thread
Blood test are split in to:
- BIOCHEMISTRY
Looks at chemicals in the blood.
Eg. Raised potassium (an intracellular electrolyte) in the blood can be a red flag.
- HAEMATOLOGY
Looks at cells in the blood (number, type and size).
Eg, Raised neutrophils may indicate infection
- BIOCHEMISTRY
Looks at chemicals in the blood.
Eg. Raised potassium (an intracellular electrolyte) in the blood can be a red flag.
- HAEMATOLOGY
Looks at cells in the blood (number, type and size).
Eg, Raised neutrophils may indicate infection
Reference ranges represent the 'normal values' in 95% of the healthy population.
The normal range will vary according to age, gender and local population.
Theoretically, 5% of healthy individuals' results will lie outside of this range.
The normal range will vary according to age, gender and local population.
Theoretically, 5% of healthy individuals' results will lie outside of this range.
So if your patient's result falls outside of the reference range, how do you decide whether it is indicative of pathology?
We must consider
1. How far out of range is the result?
2. Does it fit with our patient's symptoms?
3. Do the other blood test results agree?
4. Is the test reliable?
1. How far out of range is the result?
2. Does it fit with our patient's symptoms?
3. Do the other blood test results agree?
4. Is the test reliable?
But first we need to understand what we are measuring. This can be split in to four categories.
Keep scrolling....
Keep scrolling....
1. Leakage of cellular content.
Stuff that should be IN the cells can leak in to the blood.
Eg 1. When muscle breaks down (eg from injury), it's cells can release creatine kinase, raising levels in the blood.
Eg 2. Bony lysis from some cancers can cause hypercalaemia.
Stuff that should be IN the cells can leak in to the blood.
Eg 1. When muscle breaks down (eg from injury), it's cells can release creatine kinase, raising levels in the blood.
Eg 2. Bony lysis from some cancers can cause hypercalaemia.
2. Clearance of waste products
The liver and kidney usually remove waste products.
If one is not functioning properly, there might be raised concentrations of waste products in the blood (e.g. Urea/bilirubin)
The liver and kidney usually remove waste products.
If one is not functioning properly, there might be raised concentrations of waste products in the blood (e.g. Urea/bilirubin)
3. Production
If the organs involved in producing cells in the blood are not functioning well, the number of these cells may be reduced.
Conversely, cell damage or infection for example can stimulate an increase in production of WBCs and CRP, elevating their levels.
If the organs involved in producing cells in the blood are not functioning well, the number of these cells may be reduced.
Conversely, cell damage or infection for example can stimulate an increase in production of WBCs and CRP, elevating their levels.
4. Interaction
Some blood tests are influenced by more than 1 system.
Eg, HBA1C is haemoglobin with glucose stuck to it. If glucose it stuck to Hb, it's probably also stuck to nerves (diabetic neuropathy), eyes (retinopathy) or kidneys.
Some blood tests are influenced by more than 1 system.
Eg, HBA1C is haemoglobin with glucose stuck to it. If glucose it stuck to Hb, it's probably also stuck to nerves (diabetic neuropathy), eyes (retinopathy) or kidneys.
Aaaaaand I'll have to do some more reading and come back with a follow up thread soon if it's helpful!
Hope you enjoyed this one.
Here's the book - highly recommend!
Hope you enjoyed this one.
Here's the book - highly recommend!
Thread 2 now posted here: https://twitter.com/palingclaire/status/1334519307485720578?s=21
