Routine blood tests can provide useful information about your general health, but they do not necessarily answer every health question. Depending on your symptoms, medical history and risk factors, a healthcare professional may recommend additional tests to investigate nutritional deficiencies, hormonal concerns, metabolic health or cardiovascular risk.
A recent social-media post by Kolkata-based dietitian and health and fitness coach Nikita Bardia highlighted nine tests that are not always included in basic health panels. The tests mentioned included ferritin, homocysteine, hs-CRP, reverse T3, vitamin D, calcium, advanced lipid markers, fasting insulin and magnesium.
However, not every test is appropriate for everyone, and some of these tests are not routinely recommended as general screening tests. Their usefulness depends on the individual and the clinical situation.
1. Ferritin: More Than Just Haemoglobin
Haemoglobin is commonly checked to assess for anaemia, but ferritin measures the body’s stored iron.
Low ferritin can indicate depleted iron stores, sometimes even before obvious anaemia develops. Doctors may consider ferritin testing when someone has symptoms such as unexplained tiredness or when iron deficiency is suspected.
Ferritin levels can also be affected by inflammation, so the result needs to be interpreted alongside other laboratory findings and symptoms.
2. Homocysteine
Homocysteine is an amino acid measured in the blood. Elevated levels can sometimes be associated with deficiencies of nutrients such as vitamin B12 and folate, among other factors.
A doctor may recommend the test in particular situations, especially when there is a reason to investigate nutritional deficiencies or certain metabolic concerns.
It should not, however, be treated as a standalone test for “ageing” or cognitive decline.
3. High-Sensitivity CRP (hs-CRP)
High-sensitivity C-reactive protein can detect low levels of inflammation.
Unlike a standard CRP test, hs-CRP is particularly used in certain cardiovascular-risk assessments. However, CRP can rise because of infections, injuries and many other conditions, so a single elevated result does not automatically indicate a chronic health problem.
4. Reverse T3
Reverse T3 is a thyroid hormone metabolite. Although it may sound useful when someone has ongoing fatigue despite a normal TSH result, reverse T3 is not routinely recommended for evaluating thyroid function in most people.
For suspected thyroid disease, doctors generally rely on established tests such as TSH and, when appropriate, free T4 and other investigations based on symptoms.
Anyone experiencing persistent fatigue should discuss the broader range of possible causes with a healthcare professional rather than relying on reverse T3 alone.
5. Vitamin D and Calcium
Vitamin D plays an important role in calcium absorption and bone health. A blood test for 25-hydroxy vitamin D can be used when vitamin D deficiency is suspected or when testing is clinically appropriate.
Calcium may also be measured when there is a reason to investigate bone, parathyroid, kidney or other health concerns.
The two tests provide different information and should not automatically be treated as a universal “vitamin D utilisation” test.
6. ApoB or Lipoprotein(a)
A standard cholesterol test usually reports markers such as LDL cholesterol, HDL cholesterol and triglycerides.
For some people, additional markers such as apolipoprotein B (ApoB) or lipoprotein(a), or Lp(a) can provide further information about cardiovascular risk.
These tests may be particularly relevant for people with certain cardiovascular risk factors or a strong family history of premature heart disease. Lp(a), in particular, is largely genetically determined and is generally considered a measurement that does not need to be repeated frequently.
7. Gut Health Testing
Commercial “gut health” panels may include tests related to the microbiome or intestinal permeability. One marker often discussed online is zonulin.
However, many commercially marketed gut tests have limitations, and there is not enough evidence to suggest that everyone with bloating, acne, mood changes or digestive symptoms needs such testing.
If someone has persistent digestive symptoms, a doctor may instead recommend targeted investigations based on the symptoms and medical history.
8. Fasting Insulin
Blood glucose and HbA1c are commonly used to assess blood-sugar regulation and diabetes risk.
Fasting insulin can provide additional information in certain clinical or research settings, but there is no single universally accepted “ideal” fasting insulin range that applies to everyone.
People with symptoms or risk factors for insulin resistance should discuss appropriate testing with their doctor rather than interpreting one insulin result in isolation.
9. Magnesium
Magnesium is an essential mineral involved in muscle and nerve function, energy production and many other processes.
A blood magnesium test may be useful when deficiency is suspected, although standard serum magnesium does not always perfectly reflect the body’s total magnesium stores.
People with certain medical conditions, poor nutritional intake or medications that affect magnesium levels may have a greater reason to discuss testing with a healthcare professional.
Do You Really Need All Nine Tests?
Not necessarily.
A longer list of blood tests does not automatically mean a better health check-up. Unnecessary testing can sometimes produce borderline or abnormal results that create anxiety and lead to further investigations that may not be needed.
The right tests depend on factors such as:
- Your age and sex
- Symptoms you are experiencing
- Diet and nutritional intake
- Family history
- Existing medical conditions
- Medications and supplements
- Previous test results
- Specific cardiovascular, metabolic or hormonal risk factors
For example, someone with unexplained fatigue may require a very different set of investigations from someone with a strong family history of cardiovascular disease.
The Bottom Line
Routine blood tests are useful, but they are not designed to detect every possible health concern. Additional testing can sometimes provide valuable information when there is a specific clinical reason to investigate further.
At the same time, tests promoted on social media should not automatically be considered essential for everyone. A healthcare professional can help determine which tests are actually appropriate based on your symptoms, medical history and individual risk factors.
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Do not order or interpret medical tests solely on the basis of social-media recommendations. Always consult a qualified healthcare professional about which tests are appropriate for you.
Source note: The list of nine tests discussed in this article was inspired by claims shared in a social-media video. The claims have not been independently verified, and the inclusion of a test in this article does not mean that it is routinely recommended or medically necessary for everyone.