Chemical Composition of Blood Plasma

• Terms. Mechanics of investigation.• High- and low- MW compounds of bl.pl.• Interpretation of investigations in clinical

practice: – “Basic set”– Disorders of the kidneys and internal

environment– Inflammation – Liver disorders

• Serum = liquid remaining after clotting– usefull for most biochem. tests

• Plasma = whole blood - cells – emergency tests– small samples (yield is greater)– clotting tests

• The mechanics of investigations– Blood collection: venepuncture

Basic terms and mechanics of investigation

Biochemical abnormalities are important markers of disease

• Diagnosis = history + examination + biochemical tests + imaging techniques

• Treatment: monitoring of the response to therapy in both acute and chronic disorders

• Prognosis and secondary prevention• Screening: detecting the non-apparent

disease, eg. PKU or hypothyreosis

Low-molecular weight compounds of blood plasma

• Cations: Na+, K +, Ca + +

• Anions: Cl-, HCO3-, HPO4

2-, HSO4-

• Metabolites: urea, creatinine, uric acid, bilirubin

• Nutrients: glucose, FFA, ketones

• Other

+

High MW compounds of blood plasma (= proteins)

• According to the function– oncotic pressure – clotting factors and fibrinolytic agents– transport: binding proteins, apoproteins– antibodies and complement: IgG, IgM– buffers– none: enzymes used for diagnostics

• Electrophoretic separation: prealbumin, albumin, α-, β-, γ-globulines

Internal environment and the blood buffers

• Basic life conditions: – isoionia: concentrations of certain ions must

be kept in narrow range– isoosmia: osmotic pressure is allways the

same in ECS and in cells (in dehydratation osmotic pressure rises)

– isohydria: pH = 7.35 - 7.45

• Blood buffers: bicarbonate, hemoglobine, proteins and phosphate

Internal environment investigation

• Water metabolism: osmolality, Na+

• Acid-base balance disordes: “Astrup“– taken from arterial blood

– pH, pO2, pCO2, HCO3-, BE, BB, AG, lactate

• Kidney failure: K+, urea, creatinine, phosphate and sulphate retention

• Respiration failure: pO2 decrease with/without pCO2 increase

Inflammation

• History + examination

• Changes in the blood count (eg. leucocytosis) and sedimentation rate

• Non-specific inflammatory markers: eg. CRP and fibrinogen

• Specific antibodies: IgG or IgM (ELISA)

• Antigen assays: eg. HBsAg

Assays for liver and billiary tract function and disease

• Parenchyme damage: – increase in enyzme activity in plasma:

ALT, AST, ALP, GMT

• Alteration of liver function:– bilirubin accumulation (jaundice)– alteration of protein synthesis:

hypoalbuminaemia, clotting disturbancies

„Basic set“

• Taken from most of the patients admitted to hospital

• Give to the physician basic overview about patient’s metabolic state and organ functions

• Contains:– Na, K, Cl, glycaemia– liver set: ALT, AST, bilirubin, (ALP, GMT)– kidney set: urea, kreatinine– blood count and FW– urine examination + sediment