Know your body numbers

Keeping tabs on your key health measures.
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02.Measurements your doctor should take

For some measures you need the help of your doctor, or referral to a pathology service in the case of blood tests.

Blood pressure

body numbers heartBlood pressure is the force of the blood pushing against the walls of the arteries as your heart pumps it round your body. It’s always given as two numbers:

  • The top number, systolic pressure, indicates the pressure in the arteries when the heart beats, pumping blood.
  • The bottom number, diastolic pressure, represents the pressure as the heart relaxes between beats.

Untreated high blood pressure, or hypertension, can contribute to atherosclerosis, a hardening of the arteries and a build-up of fatty deposits called plaque. This in turn can lead to cardiovascular disease, heart attack and stroke. Hypertension is sometimes called the silent killer because it usually has no symptoms — you can have high blood pressure and feel perfectly well.

Smoking, physical inactivity, overweight/obesity, poor nutrition and excessive alcohol consumption can all increase your risk of hypertension. Lifestyle changes can successfully control high blood pressure in many cases, especially if addressed in the early stages.

Aim for:

Less than 120/80mmHg. In general, lower is better, although very low blood pressure can sometimes be a cause for concern and should be checked out by a doctor.

When should I check it?

Every two years from age 18 if it’s “normal”. If you have a personal or family history of hypertension, stroke or heart attack, you’ll need to check it more frequently.

Pressure difference between arms

A small difference of 5mmHg blood pressure between right and left arms is normal. But a repeatedly measured difference in systolic blood pressure of more than 10mm Hg between left and right arms can indicate increased risk of future cardiovascular disease. A difference of more than 20mmHg for systolic or 10mmHg diastolic can indicate blocked arteries in one arm. This could be a sign of peripheral artery disease, which may also affect blood vessels in the brain and heart. Other potential problems with large blood pressure differences between arms include kidney disease, diabetes and heart defects.

It’s good practice for your doctor to measure both arms to determine which has higher pressure, and use that as the basis for treatment and the benchmark for assessing changes in the future. However, most doctors measure the arm that’s closer to them – in apparently healthy patients at least.

Aim for:

Less than 10mmHg difference in systolic blood pressure between right and left arms.

When should I check it?

Whenever your blood pressure is measured.


body numbers syringeCholesterol is a lipid (fatty substance) that occurs naturally in your body. It’s essential in order for you to function properly, but your body generally makes all it needs. Eating too much saturated fat leads to excessive cholesterol in your blood, which can increase your risk of heart disease and stroke.

Smoking, hypertension and being overweight are also risk factors for high cholesterol. Like high blood pressure, high blood cholesterol doesn’t produce any symptoms and many people first learn they have it only after a heart attack or stroke.

Cholesterol is transported in the blood by carriers called lipoproteins, of which there are two main types:

  • low-density lipoprotein (LDL), usually referred to as “bad” cholesterol because it can clog up your arteries, and
  • high-density lipoprotein (HDL), known as “good” cholesterol because it helps take cholesterol out of the bloodstream.

The lipid profile from a fasting blood test gives you a breakdown of total cholesterol, HDL, LDL and triglycerides (another form of fat) in your blood. A finger-prick cholesterol test, such as the type offered in some pharmacies, gives you total cholesterol only. They’re not as accurate as a fasting blood test; if it finds your total cholesterol is OK it probably is, but if it says it’s too high, get a proper test done.

Certain lipid ratios are risk factors for some conditions. Having high triglycerides and low HDL and/or high total cholesterol is a risk factor for pre-diabetes, for example, so it’s useful to know all the numbers.

Aim for:

  • Total cholesterol: below 4 mmol/L
  • LDL: below 2 mmol/L
  • HDL: above 1 mmol/L
  • Triglyceride: below 1.5 mmol/L

The target levels may be more lenient if you’re not in a high-risk group. But in general any lowering of total and LDL cholesterol levels and any raising of HDL cholesterol can be beneficial, even if you’re not reaching the target.

Sometimes the ratio of total cholesterol to HDL cholesterol is a better indicator of atherosclerosis risk. So if your total cholesterol is 5.1 and your HDL is 1.4, your ratio is 3.6. The lower the ratio, the better. Aim for a ratio <5. Around 3.5 is ideal. However, absolute numbers are a better guide for treatment.

When should I check it?

Every five years from age 45, but more frequently if you’re considered at moderate or high risk for cardiovascular disease.

Blood glucose

body numbers checklistLevels of glucose in your blood are controlled by insulin, and when your body’s insulin isn’t working effectively this can result in low blood glucose (hypoglycaemia) or high blood glucose (hyperglycaemia).

Chronic hypoglycaemia can lead to brain and nerve damage. Chronic hyperglycaemia indicates diabetes, which, if left untreated, can cause progressive damage to body organs such as the kidneys, eyes, heart, blood vessels and nerves.

Almost one in four adults over the age of 25 has either diabetes or a condition known as pre-diabetes (impaired glucose metabolism). People with pre-diabetes are more likely to get type 2 diabetes and are at risk of heart disease. If caught in the pre-diabetes stage, lifestyle changes can reduce the likelihood of progressing to full-blown type 2 diabetes.

A fasting blood glucose test can determine if your blood glucose level is within a healthy range.

Aim for:

3.6 to 5.4 mmol/L.

When should I check it?

The Royal Australian College of General Practitioners recommends screening for diabetes using the AUSDRISK screening tool every three years from age 40. Start at 18 if you’re Aboriginal or Torres Strait Islander. A blood glucose test is recommended for those determined by AUSDRISK to be at higher risk of diabetes or with other high-risk medical conditions, such as polycystic ovary syndrome or a previous cardiovascular event (stroke or heart attack) with regular blood tests thereafter. 

For more information on some of the medical conditions mentioned, or for general health information see our food and health section.


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