Sydney GP Dr Leanne Girgis on the blood tests worth asking about in your 40s, what often turns up in women who feel well, and what to do when the results land.

As a Sydney-based general practitioner, I feel that not all tests are appropriate for everyone, and I don't believe in blanket screening. The most useful approach in women in their 40s is individualised testing based on multiple factors, including current symptoms, targeted history-taking to identify issues a patient may not have considered, as well as family history, lifestyle and overall risk profile.

Which Blood Tests Give the Best Picture of Overall Health in Your 40s?

That said, there are a number of blood tests that can provide a very helpful picture of overall health and often identify risks or early changes before symptoms become apparent.

Full Blood Count

One of the most useful starting points is a full blood count. It's a simple test, but it can provide important information about anaemia, infection and general immune and inflammatory status.

Iron Studies and Ferritin

Iron studies, particularly ferritin, are especially important in women who are still menstruating. Iron deficiency is one of the most common issues I see, and it can occur even when haemoglobin is normal. Low iron stores can contribute to fatigue, reduced exercise tolerance, hair shedding, brain fog and poor concentration.

Vitamin B12 and Folate

Vitamin B12 and folate may also be worth assessing in the right context, particularly in women with dietary restrictions, gastrointestinal conditions or symptoms such as fatigue or neurological changes.

Vitamin D

Vitamin D is another common deficiency, even in sunny climates like ours here in Australia. It plays an important role in bone health, muscle function, immune regulation and overall metabolic health. Testing is most useful in those with risk factors, such as limited sun exposure, or symptoms consistent with deficiency.

Blood Sugar and Cholesterol

From a metabolic and cardiovascular perspective, a fasting glucose and HbA1c provide insight into blood sugar regulation and early insulin resistance. A lipid profile is also important, as cardiovascular risk begins to change well before menopause.

Liver and Kidney Function

Liver and kidney function tests are useful as part of a general health overview, particularly given the rising prevalence of conditions such as fatty liver disease, which is often asymptomatic in its early stages.

Thyroid Function

Thyroid function testing is best guided by symptoms. Thyroid disorders become more common in women with age and can present with very non-specific symptoms including fatigue, weight changes, mood changes, constipation, dry skin and hair changes.

Can a Blood Test Diagnose Perimenopause?

One important point is that reproductive hormone testing is often misunderstood. In perimenopause, hormones such as oestrogen and FSH fluctuate significantly, which means a single blood test is often not reliable for diagnosis. In most cases, the clinical picture – symptoms and menstrual history – is far more informative than blood tests alone.

Ed's note: For the skin side of perimenopause, see our guide to priming your skin for peri and menopause.

What Commonly Turns Up in Women Who Feel Well?

Interestingly, some of the most common findings in women who feel "generally well" include low iron stores, vitamin D deficiency, early insulin resistance, elevated cholesterol and occasionally borderline thyroid changes. These are subtle shifts that can develop gradually over time.

What Should You Do When Your Results Come Back?

When results are abnormal, the first step is not immediately medication – it's interpretation. We look at the broader context: diet, sleep, stress, physical activity, alcohol intake and medications. Many of these markers can improve significantly with targeted lifestyle changes such as improving protein intake, increasing resistance training, correcting nutrient deficiencies, optimising sleep and addressing metabolic health early. Supplementation or medication is then considered when appropriate.

What About Cancer Screening in Your 40s?

Ed's note: Blood tests are separate from Australia's national cancer screening programs. Cervical screening is recommended every five years from age 25 to 74, a free at-home bowel screening kit is available from age 45 (every two years), and BreastScreen invites women aged 50 to 74 every two years, although women aged 40 to 49 can also take part. Cancer Council Australia has the detail, and your GP can talk you through what suits your own history.

Is More Testing Always Better?

Ultimately, I see testing in the 40s as a tool for prevention and optimisation. The goal is not to over-test, but to use the right tests at the right time to better understand what is happening beneath the surface and support healthy ageing over the long term.

Ed's note: Dr Girgis is the health expert in the Beauticate Collective.

This article is general information from a GP, not personal medical advice. Speak to your own doctor about which tests are right for you.