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Health by numbers

Health by numbers

Getting your medical test results can be overwhelming if you don’t know how to read them. Editor-at-large Niki Bezzant helps make sense of it all.

Blood pressure

What it measures

When the heart beats, it pumps blood around the body. As the blood moves, it pushes against the sides of the blood vessels.

When a doctor checks blood pressure, they’re checking how strong this push is in our arteries.

What it means

You’ll hear two numbers when you have your blood pressure measured.

1 The higher number is the systolic blood pressure. This is the pressure of blood against artery walls as it pumps when the heart beats.

2 The lower number is the diastolic blood pressure. This is the pressure when the heart is resting between beats.

What’s healthy?

An ideal blood pressure is between 90/60 and 120/80.

  • If your blood pressure is between 120/80 and 140/90, it’s considered slightly raised and is called pre-hypertension.
  • If your blood pressure is consistently 140/90 or greater, this is considered high, and is called hypertension.

Low blood pressure (hypotension), where systolic pressure is below 90 or diastolic is below 60, is only a problem if you have symptoms such as dizziness. Some people have naturally low blood pressure and people who are very fit can also have low blood pressure.

High blood pressure (hypertension) puts extra strain on the arteries and heart, which may lead to heart attacks and strokes.

How to change it

For some, there will be an underlying cause of hypertension which needs to be addressed. But for most, there are lifestyle changes that can help lower high blood pressure. When it comes to food, cutting sodium intake is key.

The ‘DASH’ diet (Dietary Approaches to Stop Hypertension) has been shown to successfully lower high blood pressure. The diet avoids processed food and encourages 8-plus fruit and vege serves a day (increasing potassium, helping offset the effects of sodium), 2-3 servings daily of low-fat dairy (calcium for heart health) wholegrain cereals, nuts and seeds (high in magnesium to help reduce blood pressure).

Eating this way may also promote weight loss, which on its own can help lower blood pressure in people who are overweight. Being more physically active and cutting down on alcohol will also help.

Medication may also be prescribed to control blood pressure.

Blood sugar (glucose) HbA1c

What it measures

The body gets glucose from the carbohydrates we eat and uses it for energy. In order to keep our blood glucose within a tight range, the absorption, storage and release of glucose is regulated constantly by complex processes involving the small intestine, liver and pancreas. If our blood glucose gets out of balance and becomes consistently too high, we can develop type 2 diabetes.

Blood sugar (blood glucose) is checked via a blood test known as HbA1c. It gives an average of your blood sugar levels over the past two to three months.

What it means

The higher your blood sugar levels are, the more glucose attaches to your red blood cells. The HbA1c test measures this. When you have diabetes or pre-diabetes, the amount of glucose in your bloodstream is higher than normal.

What’s healthy?

HbA1c is expressed as a number:

  • HbA1c of 40 or lower is considered normal.
  • HbA1c between 41 and 49 is considered pre-diabetes.
  • HbA1C of 50 or higher suggests you have type 2 diabetes.

How to change it

If you’re diagnosed with pre-diabetes, there are lifestyle changes that can stop this developing into type 2 diabetes, or at least slow it right down. For more on this, see the Diabetes Toolkit. The basic advice is:

  • Lose weight if you need to
  • Eat a healthy diet full of unprocessed foods: vegetables, whole grains, nuts, seeds, lean protein and healthy fats
  • Move your body regularly.

Medication may also be prescribed for pre-diabetes and type 2 diabetes.

People with type 1 diabetes, which is an autoimmune disease, must take insulin to control their blood sugar.

Blood fats (lipids) Cholesterol and triglycerides

What it measures

Cholesterol is one of the fats circulating in our blood. Most of it is produced in the liver and we get some from food. It helps essential bodily functions such as producing hormones and building cell walls.

Cholesterol tests measure low density lipoproteins (LDL) and high density lipoproteins (HDL). Results are expressed as a series of numbers – LDL (‘bad’) cholesterol, HDL (‘good’) cholesterol, total cholesterol, and the ratio of total to HDL.

Triglycerides are another type of fat that circulate in our blood. They are stored in fat cells and released into the blood when we need more energy.

What it means

LDLs take cholesterol from the liver to our organs via the blood vessels and are prone to depositing some of the cholesterol on blood vessel walls on the way. This can lead to fatty build-up and, subsequently, narrowed arteries, increasing risk of heart disease, which is why we don’t want our levels too high.

HDLs clear cholesterol from our blood vessels and take it back to the liver for processing, which is why we don’t want our levels to be too low.

It’s normal to have some triglycerides circulating in the blood but high levels are not good for heart health as they can contribute to thickening of the arteries.

What’s healthy?

There is no ‘normal’ for lipids. Ideal numbers will depend on a person’s cardiovascular disease risk. A person who has had a heart or stroke event or is at high CVD risk will aim to keep within the following numbers:

  • Total cholesterol – less than 4.0 mmol/L
  • Triglyceride – less than 1.7 mmol/L
  • LDL-cholesterol – less than 2.0 mmol/L
  • HDL-cholesterol – 1.0 mmol/L or more
  • Total cholesterol to HDL ratio – less than 4

How to change it

Lowering or managing your cholesterol and triglycerides is just one factor for heart health. But, many of the things we know are great for general health will also help keep your blood fats under control such as eating lots of plant foods, choosing healthy fats (olive oil, nuts, seeds, avocado) and cutting down on saturated fats. Choosing whole grains over refined carbs and eating legumes is beneficial, as well as exercising regularly.

BMI

What it measures

BMI (body mass index) is expressed as a number calculated by dividing weight in kilograms by height in metres squared (kg/m2).

Although BMI in populations corresponds with body fatness, for individuals it varies according to several factors, such as how much of your weight is fat versus muscle mass. So, for some people, for example large muscled athletes, BMI is simply not appropriate.

What it means

BMI is used to measure risk of certain health conditions. It’s a controversial tool because it’s more useful for populations than individuals and BMI value and health-condition risk varies by ethnicity. A health professional may calculate your BMI but it’s only one of a range of measures that could indicate problems to do with weight.

What’s healthy?

For adults 18 years and over these measures are used, among others, to indicate a risk for health conditions.

A BMI between 25-29.9 indicates an increased risk for certain health conditions and at 30-plus the risks increase even more. A health professional can put your BMI in context for you, considering other factors such as body composition, sex, age, ethnicity and other health numbers.

How to change it

If your health professional advises trying to lose weight, a good place to start is the weight-loss section.

Waist circumference

What it measures

Measuring the circumference of the waist can tell us a bit about risk of certain chronic diseases, especially if we take into account other measurements. And all you need is a tape measure.

What it means

Your waist measurement can indicate overweight or obesity. If considered alongside height and/or hip measurement, it might also indicate central obesity or normal-weight obesity. Both issues can cause problems including metabolic syndrome, high blood pressure, type 2 diabetes and heart disease.

What’s healthy?

Measure around the middle of your body, about belly button level.

  • A measurement of over 94cm for a man or 80cm for a woman could indicate normal-weight obesity.
  • A measurement of over 102cm for a man or over 88cm for a woman indicates a higher risk of metabolic complications.
  • You can also do a waist to hip ratio by dividing your waist measurement by the measurement of the widest part of your hips and bum.
  • For men, a ratio below 1 is ideal
  • For women a ratio below 0.85 is ideal

How to change it

Eating well, exercising (to build muscle and lose unwanted fat) and keeping control of stress levels will all help with waist size.

Health tests of the future

Health and nutrition are personal so the health tests of the future might be personalised too.

Gene testing

Our genes affect how the body responds to certain foods. The science of nutrigenomics is in its early stages, but specialised testing is now available to determine how we deal with things like caffeine, gluten, saturated fat and sodium.

Understanding these responses may help us customise our diets and reduce risk for certain diseases. In the future, genetic testing may be offered in primary care, along with customised nutrition and lifestyle advice.

Wearables

In the future we may not ever need to go for tests. Our health may be constantly monitored via wireless devices. For example, scientists have devised a wearable patch the size of a postage stamp to measure blood pressure and collect data. They’re also working on contact lenses that can monitor blood sugar.

First published: July 2019

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