Cholesterol and Vitamin D Tests: When to Check and What They Show

A cholesterol test, sometimes called a lipid study, is usually recommended from around age 45 as part of a routine heart health check, or from age 30 for Aboriginal and Torres Strait Islander people. You may be advised to test earlier or more often if you have a family history of high cholesterol or early heart disease, high blood pressure, if you smoke, or if you carry extra weight around the middle.

The point is not the number on its own but your overall cardiovascular risk, which a GP works out by combining your results with these other factors. That is why two people with the same reading can get very different advice. If your result is high, the conversation is about lowering risk over time, which may include diet and activity changes and, for some people, medicines such as statins. Our guide to managing high cholesterol goes further, and testing matters even more if you live with type 2 diabetes.

A lipid study reports several numbers, and understanding them in plain language helps. Total cholesterol is the overall figure, and in general a level below 5.5 mmol/L is the target for people without other risk factors. Your result is then split into parts.

LDL is often called the less helpful cholesterol, where lower is better and under about 2.0 mmol/L is commonly suggested for people at higher risk. HDL is the more helpful cholesterol that helps clear fats from the blood, so here a higher number is better, ideally above 1.0 mmol/L. Triglycerides are another blood fat, with under 2.0 mmol/L generally preferred. These are general reference points rather than fixed pass or fail lines, and the right targets depend on your personal risk. Your GP reads the whole picture together, not one figure in isolation, and explains what your particular numbers mean. It is normal for targets to be stricter if you already have heart or blood vessel disease.

Vitamin D comes mostly from sunlight on the skin, so testing is aimed at people who may not get enough. That includes people with limited sun exposure, those who cover their skin for cultural or medical reasons, people with naturally darker skin, older adults, and anyone who spends most of their time indoors. A single low reading on its own is not usually a cause for alarm, though low vitamin D over time can affect bone and muscle health.

Levels are reported in nmol/L. As a general guide, 50 nmol/L or above is considered sufficient for most people, 30 to 49 nmol/L is mild deficiency, and below 30 nmol/L is moderate to severe deficiency. Because Medicare has specific criteria for who can be tested at no cost, a GP first checks whether your situation qualifies before requesting the test. If your level is low, the usual step is vitamin D supplements, and your GP can advise on the right approach for you.