Plasma proteins/clinical enzymology
Lactate Dehydrogenase (LDH)
Not normally found outside the cell, marker for tissue breakdown. Indicative of general tissue damage, hemolysis. Peaks 3-4 days post-MI.
C-Reactive Protein (CRP)
Physiological role is to bind to phosphocholineexpressed on the surface of dead or dying cells in order to activate the complement system via the C1Q complex
Alkaline Phosphatase (ALP)
Present in plasma are isoenzymes of bone, liver, kidney, placenta and intestine. Heat stability distinguished bone/liver. Rises in bile duct obstruction, liver dz.
Creatine kinase
Protein found in skeletal/cardiac muscle/brain. Rise post MI.
Amylase
Rise in plasma levels with acute pancreatitis
C-Reactive Protein (CRP)
Levels of this protein increase rapidly in resopnse to acute inflammation. Ref level 1.75 mg/L Used for early detection of acute infection
Caeruloplasmin
Low levels indicate urinary Cu excretion, Wilsons Dz, lower gene expression High levels indicate pregnancy, inflammation, RA, Alzheimers
Caeruloplasmin
Major Cu-carrying protein of the blood, plays role in iron metabolism (Ferrous Fe+3 -> Ferric Fe+2), synth in liver
Fibrinogen/clotting proteins
4% of plasma proteins essential for clotting
Ferritin
Acute phase reactant protein used as a marker for iron overdose disorders such as hemochromatosis/hemosiderosis.
Hyperalbuminaemia
Almost always caused by sever or chronic dehydration. also high protein diets.
Monoclonal spike (gamma globulin)
Characteristic of lymphoproliferative disease or myeloma on SPEP.
Haptoglobulin (alpha2-globulin)
Decreased levels imply hemolytic anaemia, esp with dec RBC, Hb, Hematocrit. Decrease without anaemia indicates liver damage. Increase implies inflammatory process
Alkaline Phosphatase (ALP)
Elevated in children due to bone growth, and in elderly due to Pagets dz.
Alanine Transaminase (ALT)
Enzyme found in liver cell cytoplasm. Elevated levels with inflammatory or infective liver condition.
Aspartate Transaminase (AST)
Enzyme found in the cytoplasm and mitochondria of hepatocytes. Elevated levels indicate infiltrative liver disease.
Hypoalbuminaemia
Symptoms: edema, reduced drug/hormone transport Causes include malnutrition, malabsorption, liver disease, overhydration, septecaemia, hypoxaemia, nephrotic syndrome, burns, haemorrhage
Serum protein electrophoresis (SPEP)
Test used to assess 5 major plasma protein groups
Alpha fetoprotein (AFP)
major plasma protein produced by the yolk sac and liver of fetus. Levels used as screening test for fetal abnormalities. Tumor marker in non-pregnant people.
Albumin
makes up 60% of plasma protein, major contributor to osmotic pressure, assists in transport of lipids and steroid hormones. synth in liver T1/2 = 17-20 days
alpha1-antitrypsin
protease inhibitor, can rise in acute infection, protects tissues from inflammatory cells, especially elastase.
Haptoglobulin (alpha2-globulin)
protein functions to bind free plasma hemoglobin, allowing Hb degradation while preventing loss of iron through the kidneys and protecting the kidneys from damage by Hb
Regulatory proteins
proteins tha make up the remaining 1% of plasma proteins, enzymes.
Troponin
striated muscle contractile unit elevated in plasma post-MI
Globulins
these proteins make up 18% of plasma proteins transport ions, hormones, lipids and assist in immune function alpha1, alpha2, beta, gamma.
