Total and HDL Cholesterol

Question 1

What is total cholesterol composed of? (introduction)

Answer 1

• HDL: high protein content, picks up cholesterol from arteries and return it to liver for excretion
• LDL: high cholesterol content, deposits cholesterol as plaques

Question 2

How is LDL linked w/ CHD? (introduction)

Answer 2

• LDL forms arterial plaques which is linked with CHD or stroke

Question 3

Total cholesterol estimation

Answer 3

• 1st enzyme releases all chol
• 2nd enzyme oxidises chol, forms hydrogen peroxide
• 3rd enzyme releases atomic O2 from hydrogen peroxide reacting w/ phenol and 4-aminoantipyrine to produce red quinonimine dye
• Measured at 500nm

Question 4

HDL estimation

Answer 4

• phosphotungistic acid/MgCl solution added, LDL and VLDL precipitate
• then centrifuged to bottom of tube, HDL still dissolved in supernatant
• chol measured in supernatant will be that of HDL

Question 5

Equation for both total and HDL cholesterol

Answer 5

• (absorbance of unknown/absorbance of std) x concentration of std = concentration of unknown

Question 6

Total cholesterol result boundaries

Answer 6

• desirable total chol: <5.17 mmol/L
• borderline high: 5.17 - 6.19 mmol/L
• high: > or = 6.20 mmol/L

Question 7

Total chol and HDL QC ranges

Answer 7

• total chol: 5.1 - 6.6 mmol/L

- HDL: 0.6 - 1.19 mmol/L

Question 8

HDL result boundaries

Answer 8

• <1.04 mmol/L = CHD high risk

- > or = 1.55 mmol/L = low risk

Question 9

Low HDL

Answer 9

• means higher LDL
• LDL causes build up of fatty acids within your arteries, reducing or blocking blood + O2 flow, leading to chest pain and heart attack
• atherosclerosis: not limited to heart arteries, also in arteries elsewhere, causing strokes, kidney failure and poor circulation

Question 10

Treatments of low HDL

Answer 10

• dietary: reduce saturated fats, trans fats and sugars, increase plant-derived sterols and fibres
• lifestyle: regular exercise, lose weight
• drugs: statins (block chol production in liver itself, lower LDL), ezetimibe (reduces dietary chol absorption), bile-acid-binding resins (prompts liver to use excess chol to make bile acids, reducing chol level

Question 11

Measuring BP (other ways in determining risk)

Answer 11

• can lead to thickening and hardening of arteries, narrowing them and thus restricting flow

Question 12

Diabetes (other ways in determining risk)

Answer 12

• share similar risk factors with CHD, such as obesity and high BP

Question 13

Assessing hs-CRP levels (other ways in determining risk)

Answer 13

• high sensitivity C-reactive protein
• appears in higher amounts when there’s inflammation
• high levels may be risk factor

Question 14

Lifestyle choices (other ways in determining risk)

Answer 14

• smoking: nicotine and CO puts strain on heart by making it work faster, increase risk of clots, lining of arteries damaged
• lack of exercise: fatty deposits build up in arteries, blocked blood supply to heart/brain = heart attack/stroke
• alcohol use: can lead to heart damage, worsens other risk factors of CHD

Question 15

Thrombosis (other ways in determining risk)

Answer 15

• blood clot in vein or artery

- if develops in coronary artery it prevents blood supply from reaching heart muscle

Question 16

Autoimmune diseases (other ways in determining risk)

Answer 16

• those with rheumatoid arthritis and lupus have increased risk of atherosclerosis

Question 17

Genetics (other ways in determining risk)

Answer 17

• family history
• hereditary
• increased CHD risk