Know your numbers

Last updated 01 September 2016 — Last reviewed 17 February 2014

How do you know if your blood pressure is too high, too low, your cholesterol is within a healthy range or whether you are actually overweight? Knowing the numbers of key health measures can help you to know if you need to make some changes for the benefit of your current and future health.

Blood pressure

blood pressure measurement

Know and understand your blood pressure numbers to make sure they are not too high. Blood pressure numbers include:

  • systolic pressures – the pressure when the heart beats while pumping blood
  • diastolic pressures – the pressure when the heart is at rest between beats

You often see blood pressure numbers written with:

the systolic number above                 such as  120
the diastolic number below                               80 mmHg

or

the systolic number first/ the diastolic number second, such as 120/80 mmHg

The mmHg is millimeters of mercury which are the units used to measure blood pressure. Normal Blood Pressure should be less than 130/80.

If you are aged 50 or younger you should have a blood pressure test every two years. If you are aged over 50 a blood pressure check every year is recommended.

You will find more information on blood pressure in our pages on managing blood pressure.

Cholesterol

Cholesterol is a fatty substance produced naturally by the body and found in blood. The liver makes about two thirds of cholesterol. Much also comes from foods, especially those high in saturated fats. Cholesterol is essential for the function of every cell in the human body, but too much is a problem.

Cholesterol consists of:

  • low density lipoprotein (LDL) cholesterol
  • high density lipoprotein (HDL) cholesterol

LDL cholesterol is known as 'bad' cholesterol because it tends to clog blood vessels, which can lead to cardiovascular disease. When a blood cholesterol reading is high, it usually means LDL levels are high. Saturated fat in the diet (e.g. fatty meat, butter, cheese) can increase LDL levels.

HDL cholesterol is sometimes called 'good' cholesterol and can help unclog blood vessels. High HDL levels are a good sign. HDL levels can be increased by eating more polyunsaturated fats (e.g. safflower oil, salmon, walnuts, sunflower seeds).

Another kind of fat found in the blood stream are called triglycerides and so when you have a cholesterol level test, the test may also measure your triglycerides. Fats in food form triglycerides; these are absorbed into the blood and then either burned for energy or deposited into the body's fat stores.

Cholesterol levels

A certain amount of cholesterol is necessary for the normal functioning of the body, but too much of it is dangerous, especially for the heart. There are general guidelines that help you to know if your cholesterol is too high, however things like family history and cultural background should also be considered when deciding if your cholesterol is too high.

Generally it is recommended that if your cholesterol is heading towards 6.0 or more, you will need to take action to reduce it. Other figures to be aware of are your good and bad cholesterol. These are also important in working out your overall heart disease risk.

  • HDL-C (good cholesterol) – aim for greater than 1.2
  • LDL-C (bad cholesterol) – aim for less than 2.5
  • TG (triglycerides) – aim for less than 2.0

If you are aged 50 or younger you should have a cholesterol test every two years. If you are aged over 50 a cholesterol check every year is recommended. More information on managing your cholesterol can be found here.

Blood Sugar

If the level of sugar in your blood is too high it can cause damage to your blood vessels and organs such as eyes, kidneys, heart and skin.

Normal Blood Sugar (Not fasting) – less than 8mmol/l;  Fasting – less than 5.5. Blood sugar greater than this may indicate diabetes and requires more testing. 

Body mass index (BMI)

One common measure of whether a person is overweight or obese is the body mass index or BMI. BMI is calculated by dividing your weight in kilograms by the square of your height in metres:

The Better Health Channel has a BMI calculator and further information about BMI. 

A BMI of:

  • under 20 is considered underweight
  • 20-25 is considered normal weight
  • 26-30 is considered overweight
  • 30 and over is considered obese

Abdominal circumference

The size of your waist can indicate if you are at risk of heart disease or diabetes. A rounder waist has an increased risk:

  • for women – if greater than 80cm
  • for men – if greater than 94cm

BMI or waist is just one measure of weight and should be considered alongside other measures of your health such as cholesterol, blood pressure and blood glucose. For instance, a woman with a BMI of 27 may be just overweight but healthy according to measures of blood pressure, cholesterol and blood glucose.

References

  1. Guidelines from Preventive Activities in General Practice 8th Edition, RACGP

This web page is designed to be informative and educational. It is not intended to provide specific medical advice or replace advice from your health practitioner. The information above is based on current medical knowledge, evidence and practice as at February 2014.

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