Blood tests: Difference between revisions

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===Clotting (CLS)===
===Clotting (CLS)===
There are a variety of tests they do, such a '''Prothrombin Time''' (PT) and '''Partial Thromboplastin Time''' (PTT). Basically though, they are used to test people before surgery, to test the effectiveness of [[anticoagulation]] or to isolate weird [[bleeding disorders]], such as [[Haemophilia]] and [[von Willibrand's disease]].
There are a variety of tests they do, such a '''Prothrombin Time''' (PT) and '''Partial Thromboplastin Time''' (PTT). They are generally used to test people before surgery, to test the effectiveness of [[anticoagulation]] or to isolate weird [[bleeding disorders]], such as [[Haemophilia]] and [[von Willibrand's disease]].


===Urea and Electrolytes (U+Es)===
===Urea and Electrolytes (U+Es)===
Generally used to assess the workings of the [[kidney]], and to check that [[electrolytes]] are in balance, and the patient isn't gonna drop dead.
Generally used to assess the workings of the [[kidney]], and to check that [[electrolytes]] are in balance, and the patient isn't gonna drop dead.
*'''Sodium''' (Na<sup>+</sup>)
*'''Sodium''' (Na<sup>+</sup>): ''135-145 mmol/L''
**'''low is [[hyponatraemia]]''': from sodium loss ([[d&v]], excessive sweating, [[kidney disease]] or [[Addison's]]), from excess fluids (drinking too much water, [[heart failure]], [[cirrhosis]], [[nephrotic syndrome]]). Sometimes your body makes too much [[ADH]], leading to extra water and thus low sodium.
**'''low is [[hyponatraemia]]''': from sodium loss ([[d&v]], thiazide [[diuretics]], excessive sweating, [[kidney disease]] or [[Addison's]]), from excess fluids (drinking too much water, [[heart failure]], [[cirrhosis]], [[nephrotic syndrome]]). Sometimes your body makes too much [[ADH]], leading to extra water and thus low sodium.
**'''high is [[hypernatraemia]]''': almost always due to excessive loss of water without enough water intake. Rarely, due to increased salt intake, [[Cushing's syndrome]], or [[diabetes insipidus]].
**'''high is [[hypernatraemia]]''': almost always due to dehydration. Rarely, due to increased salt intake, [[Cushing's syndrome]], or [[diabetes insipidus]].
*'''Potassium''' (K<sup>+</sup>) -
*'''Potassium''' (K<sup>+</sup>): ''3.7-5.2mEq/L''
*'''Creatinine''' -  
**'''low is [[hypokalaemia]]''': from potassium loss ([[diarrhoea]] and [[vomiting]], from insulin use, or from use of non potassium sparing [[diuretics]].
*'''Urea''' -
**'''high is [[hyperkalaemia]]''': caused by [[kidney disease]], [[Addison's]], injury to tissue, [[infection]], [[diabetes]] and too much IV potassium. Also caused by some types of drugs, [[NSAIDS]], [[beta blockers]], [[ACE inhibitors]] and potassium sparing [[diuretics]].
*'''Calcium''' (Ca<sup>2+</sup>)-
*'''Creatinine''' - High creatinine implies the kidneys are having issues. Main causes glomerulonephritis, pyelonepritis, [[acute renal failure]], [[deydration]] and [[shock]]. Rarely low, and not usually an issue if it is.
*'''Albumin''' -
*'''Urea''' - ''normal 2.5 - 7.9 mmol/L'' - goes high for the same reasons as creatinine.
*'''Proteins''' -
*'''Calcium''' (Ca<sup>2+</sup>)
**'''low is [[hypocalcaemia]]''': underactive [[parathyroid]], low [[Vitamin D]], [[CKD]], [[alcoholism]].
**'''high is [[hypercalcaemia]]''': two big causes: [[hyperparathyroidism]] and [[cancer]] (bony mets release calcium). Other causes are [[hyperthyroidism]], sarcoidosis, TB and kidney transplant.
*'''Albumin''' - low implies [[liver disease]], or kidney problems, inflammation, shock. High usually implies dehydration.


===Thyroid Function Tests (TFTs)===
===Thyroid Function Tests (TFTs)===
===Liver Function Tests (LFTs)===
===Liver Function Tests (LFTs)===
*'''Albumin''' (ALB) - it's the main protein in [[blood]], produced by the liver. Low albumin is seen in [[nephrotic syndrome]](where is leaked out) and [[liver failure]] (where it's not produced).
*'''Alanine Transaminase''' (ALT) - An enzyme found in liver cells. When liver cells are damaged, they leak this out, so its a marker of liver damage.
*'''Aspartate Transaminase''' (AST) - Similar to ALT, but less specific to the liver - can go up in [[heart]] damage too.
**The main use for AST is that when AST and ALT are both raised, and ALT is higher, it points to [[viral hepatitis]]. When AST is higher, it points to [[alcoholic hepatitis]]. I remember this as '''L'''O'''V'''E '''SA'''KE:
***So you can get '''v'''iral hepatitis from making '''love''' and A'''L'''Ts go up.
***'''Sake''' is a type of wine, and drinking too much gives you '''a'''lcoholic hepatitis, and your A'''S'''Ts go up.
*'''Alkaline Phosphatase''' (ALP) - is an enzyme found in the ducts of the [[biliary tree]]. Thus when there is damage or obstruction in the bile ducts, more of it gets released and goes into the blood. Also goes up in [[Paget's disease of bone]], due to increased bone turnover.
*'''Gamma glutamyl transpeptidase''' (GGT) - mostly used because it is raised in chronic alcohol abuse.
*'''Total bilirubin''' (TBIL) - amount of [[bilirubin]] in the blood.
*'''Direct bilirubin''' (Conjugated BR) - amount of conjugated bilirubin, enabling you to work out what type of [[jaundice]] is going on.
===Inflammatory markers (ESR and CRP)===
===Inflammatory markers (ESR and CRP)===
Essentially, these are used in a variety of different tests to confirm and inflammatory process has taken place. This can occur in [[infection]] but frankly, anything that makes you signficantly ill, or causes any inflammatory response can cause a rise in both of these tests.
CRP is more acute, whereas ESR remains high for weeks after an event. So CRP is more useful as a guide to what kind of effect treatment is having. Since both are not very specific, they are rarely used on their own, but in combination with other measures.

Latest revision as of 21:39, 16 June 2010

This fish is suffering from massive haematemesis which, one the one hand, is very bad news, but on the other hand, makes it very easy to do a blood test.

There are a lot of blood tests. Like, billions. We are going to tell you about the key ones.

Full Blood Count (FBC)

This is common to do. It's pretty much your standard. Especially important to do in infection, heart problems, surgery and anaemia.

White blood cell differential looks at the types of white blood cells present:

  • Haemoglobin is the amount of Hb in the blood. Normal is around 13-18g/dL in men and 11.5-16g/dL in women. High means dehydration, cancer or lung disease. Low is anaemia: check the page for causes.
  • Platelet count is the number of platelets. Normal is around 150-400x109/L. Low points to cancer, chemo or autoimmune problems, whilst high signifies haematological cancer.
  • Mean corpuscular volume (MCV) is average size of your red cells. Its raised in some anaemia, and lowered in others. Visit the Causes of anaemia page for more on types.

Clotting (CLS)

There are a variety of tests they do, such a Prothrombin Time (PT) and Partial Thromboplastin Time (PTT). They are generally used to test people before surgery, to test the effectiveness of anticoagulation or to isolate weird bleeding disorders, such as Haemophilia and von Willibrand's disease.

Urea and Electrolytes (U+Es)

Generally used to assess the workings of the kidney, and to check that electrolytes are in balance, and the patient isn't gonna drop dead.

Thyroid Function Tests (TFTs)

Liver Function Tests (LFTs)

  • Albumin (ALB) - it's the main protein in blood, produced by the liver. Low albumin is seen in nephrotic syndrome(where is leaked out) and liver failure (where it's not produced).
  • Alanine Transaminase (ALT) - An enzyme found in liver cells. When liver cells are damaged, they leak this out, so its a marker of liver damage.
  • Aspartate Transaminase (AST) - Similar to ALT, but less specific to the liver - can go up in heart damage too.
    • The main use for AST is that when AST and ALT are both raised, and ALT is higher, it points to viral hepatitis. When AST is higher, it points to alcoholic hepatitis. I remember this as LOVE SAKE:
      • So you can get viral hepatitis from making love and ALTs go up.
      • Sake is a type of wine, and drinking too much gives you alcoholic hepatitis, and your ASTs go up.
  • Alkaline Phosphatase (ALP) - is an enzyme found in the ducts of the biliary tree. Thus when there is damage or obstruction in the bile ducts, more of it gets released and goes into the blood. Also goes up in Paget's disease of bone, due to increased bone turnover.
  • Gamma glutamyl transpeptidase (GGT) - mostly used because it is raised in chronic alcohol abuse.
  • Total bilirubin (TBIL) - amount of bilirubin in the blood.
  • Direct bilirubin (Conjugated BR) - amount of conjugated bilirubin, enabling you to work out what type of jaundice is going on.

Inflammatory markers (ESR and CRP)

Essentially, these are used in a variety of different tests to confirm and inflammatory process has taken place. This can occur in infection but frankly, anything that makes you signficantly ill, or causes any inflammatory response can cause a rise in both of these tests.

CRP is more acute, whereas ESR remains high for weeks after an event. So CRP is more useful as a guide to what kind of effect treatment is having. Since both are not very specific, they are rarely used on their own, but in combination with other measures.