Cardiovascular Risk Marker
In several studies, the ApoB / ApoA1 ratio has been shown to be a more significant cardiovascular risk factor than the classic ratio of LDL cholesterol to HDL cholesterol.
For example, in a 2008 study that appeared in the prestigious journal The Lancet*, the ApoB / ApoA1 ratio presented a very high PAR for acute myocardial infarction, equal to 54% and higher than that of the C-LDL / C-HDL ratio (37%) and the C-total / C-HDL ratio (32%). These differences were consistent across all ethnic groups, men and women, and across all ages.
More accurately identifying those at cardiovascular risk translates into better opportunities for early intervention and prophylactic / therapeutic success. This is why in the near future the ApoB / ApoA1 relationship will presumably find an ever greater space in the clinical setting.
* Lipids, lipoproteins, and apolipoproteins as risk markers of myocardial infarction in 52 countries (the INTERHEART study): a case-control study.
Lipoproteins and Apoproteins
As most people know, cholesterol circulates in the blood inside lipoprotein aggregates (essentially composed of lipids of various kinds and proteins). Based on the percentage of the various components and their size, these aggregates - generically called lipoproteins - are classified into VLDL, LDL, IDL and HDL.
The liver incorporates cholesterol into VLDL, precursor molecules of IDL and LDL: all these molecules are characterized by the presence of the Apoprotein ApoB100 and are used to distribute cholesterol to various tissues. HDL lipoproteins, on the other hand, are necessary for the reverse transport of cholesterol from the tissues to the liver (where it is recycled or "eliminated" with the bile) and therefore have a "preventive action on the deposition of cholesterol in the arteries (high levels of HDL represent a factor protective for cardiovascular diseases). HDL lipoproteins are characterized by the presence of the Apoprotein ApoA1.
The apoproteins have the task of stabilizing the entire particle, activating the enzymes responsible for their metabolism and acting as a recognition site for the cellular receptors responsible for the uptake of lipoproteins and their removal from the circulation.
Like lipids, apolipoproteins do not identify a specific lipoprotein particle. The same apoprotein can in fact be present, albeit in different concentrations, in lipoproteins belonging to different classes (see table). In any case, almost all ApoA-I are present on HDL lipoproteins, as well as almost all APOB-100 derive from LDL.
amino acids
Why measure the APOB / APOA1 ratio
As we have seen, class B apoproteins are not exclusive to LDL cholesterol; for this reason their plasma concentrations also depend on the presence of other lipoproteins with an atherogenic potential, in this case VLDL and IDL. Based on this assumption, it is explained why in some epidemiological studies the APOB / APOA1 ratio proved to be the best predictor of cardiovascular disease compared to other traditional ratios, such as LDL / HDL, TG / HLDL or (Total cholsterol - HDL) / HDL ).
- By measuring ApoB we can quantify the total amount of all atherogenic or potentially atherogenic lipoproteins that carry this apoprotein [such as LDL, VLDL, IDL and Lipoprotein (a)] and that contribute to cardiovascular risk.
- Another advantage is that the value of the two apolipoproteins is not influenced by food intake. In other words, ApoA1 and ApoB do not appear to depend on the subject's fasting condition.
- Finally, the determination for clinical uses of ApoA1 and ApoB is standardized, simple and inexpensive.
As stated above, a person who aspires to a low cardiovascular risk should have low ApoB levels and high ApoA1 levels. By measuring both of these apolipoproteins and expressing them in the ApoB / ApoA1 ratio it is possible to obtain a strong marker of cardiovascular risk.
Desirable values of the ApoB / ApoA1 ratio should be between 0.3 and 0.9. Values above 0.9 for men and 0.8 for women indicate a high cardiovascular risk.
Select Blood Tests Blood Tests Uric acid - uricaemia ACTH: adrenocortitotropic hormone Alanine amino transferase, ALT, SGPT Albumin Alcoholism Alphafetoprotein Alphafetoprotein in pregnancy Aldolase Amylase Ammonemia, ammonia in the blood Androstenedione Antibody-endomysial antibodies Anti-gliadicides Nucleus Helicobacter pylori antibodies Embryo carcinoal antigen - CEA Prostate specific antigen PSA Antithrombin III Haptoglobin AST - GOT or aspartate aminotransferase Azotemia Bilirubin (physiology) Direct, indirect and total bilirubin CA 125: tumor antigen 125 CA 15-3: tumor antigen 19-9 as tumor marker Calcemia Ceruloplasmin Cystatin C CK-MB - Creatine kinase MB Cholesterolemia Cholinesterase (pseudcholinesterase) Plasma concentration Creatine kinase Creatinine Creatinine Creatinine clearance Chromogranin A D-dimer Hematocrit Blood culture Hemocrome Hemoglobin Glycated hemoglobin a Blood tests Blood tests, Down syndrome screening Ferritin Rheumatoid factor Fibrin and its degradation products Fibrinogen Leukocyte formula Alkaline phosphatase (ALP) Fructosamine and glycated hemoglobin GGT - Gamma-gt Gastrinemia GCT Glycemia Red blood cells Granulocytes HE4 and Cancer at "Ova" Immunoglobulins INR Insulinemia Lactate dehydrogenase LDH Leukocytes - white blood cells Lymphocytes Lipases Tissue damage markers MCH MCHC MCV Metanephrines MPO - Myeloperoxidase Myoglobin Monocytes MPV - average platelet volume Natremia Neutrophils Homocysteine Thyroid hormones OGTT Osmocyte Plasma protein A associated with pregnancy Peptide C Pepsin and pepsinogen PCT - platelet or platelet hematocrit PDW - distribution width of platelet volumes Platelets Plateletpenia PLT - number of platelets in blood Preparation for blood tests Prist Test Total IgEk Protein C (PC) - Protein C Activated (PCA) C Reactive Protein Rast Protein Test Specific IgE Reticulocytes Renin Reuma-Test Oxygen Saturation Sideremia BAC, BAC TBG - Thyroxine Binding Globulin Prothrombin Time Partial Thromblopastin Time (PTT) Activated Partial Thromboplastin Time (aPTT) Testosterone Testosterone: free and bioavailable fraction Thyroglobulin Thyroxine in the blood - Total T4, free T4 Transaminases High transaminases Transglutaminase Transferrin - TIBC - TIBC - UIBC - saturation of transferrin Transtyretin Triglyceridemia Triiodothyronine in the blood - Total T3, free T3 Troponin TRH and Troponins of s thymol to TRH TSH - Thyrotropin Uremia Liver values ESR VDRL and TPHA: serological tests for syphlis Volemia Conversion of bilirubin from mg / dL to µmol / L Conversion of cholesterol and triglyceridemia from mg / dL to mmol / L Conversion of creatinine from mg / dL to µmol / L Conversion of blood glucose from mg / dL to mmol / L Conversion of testosteronemia from ng / dL - nmol / L Conversion of uricemia from mg / dL to mmol / L
