When it comes to feeling your best year after year, prevention is powerful. Annual lab work helps catch imbalances before they become full-blown health issues — giving you the chance to take action early. Most routine physicals don't include these labs (or maybe just one or two of them). If your PCP is not ordering these labs, then you should be requesting these to be run.

Here are the five labs I recommend running every year — and why they matter.

1. Vitamin D — Your Immune and Mood Booster

Vitamin D is essential for healthy bones, immune defense, and even hormone balance. Low levels can lead to fatigue, poor immune function, and increased risk for chronic conditions like osteoporosis or autoimmune flares.

Optimal Range: Functional medicine typically aims for 50–80 ng/mL — higher than the “normal” lab range — to support optimal health.

Why Test Annually: Levels can fluctuate with seasons, sun exposure, and lifestyle changes, so it’s important to recheck yearly (or more often if you’re supplementing). It can be difficult to get an adquate amount from food and sunlight. Most people will require some form of supplementation.

2. Fasting Insulin — The Early Metabolism Marker

Most people check fasting glucose — but insulin rises long before blood sugar does. Elevated fasting insulin can indicate insulin resistance (a precursor to prediabetes) years before diabetes shows up on standard labs.

Optimal Range: Ideally under 8 µIU/mL, and closer to 2–5 for metabolic health.

Why Test Annually: This test helps you catch metabolic issues early, so you can make changes to diet, exercise, and stress before blood sugar becomes a problem. This can correct and reverse an issue long before diabetes becomes a diagnosis.

3. Full Thyroid Panel — Not Just TSH

A single TSH test doesn’t tell the full story. A full thyroid panel includes TSH, Free T4, Free T3, Reverse T3, and Thyroid Antibodies. Together, these show whether your thyroid is underactive, overactive, or struggling due to autoimmune triggers.

Why Test Annually: Thyroid issues are common, especially in women, and can cause symptoms like fatigue, weight gain, hair loss, and brain fog — even if TSH looks “normal.” A full panel gives a clearer picture of thyroid health.

4. Ferritin — Your Iron Storage Tank

Ferritin measures stored iron, which is crucial for energy, thyroid function, and oxygen delivery. Both low and high ferritin can cause fatigue and other symptoms.

Optimal Range: Generally 50–100 ng/mL for most women, though ideal ranges vary based on age, hormones, and inflammation status.

Why Test Annually: Iron can drop with heavy periods, pregnancy, or dietary changes — but can also build up in certain genetic conditions. Yearly checks ensure you stay in balance.

5. RBC Magnesium — The Inside-the-Cell Measurement

Magnesium supports hundreds of biochemical reactions — from muscle relaxation to stress response to blood sugar control. The problem? Serum magnesium tests aren’t very accurate. RBC (red blood cell) magnesium tells you what’s inside the cells, where it matters most.

Optimal Range: Mid- to upper-range of the lab’s reference interval.

Why Test Annually: Modern diets and stress levels make magnesium deficiency common, and symptoms like muscle cramps, anxiety, and poor sleep can be early clues.

By checking these five labs each year, you can:

1. Catch nutrient deficiencies early

2. Identify hormonal or metabolic issues before they escalate

3. Personalize your diet, supplements, and lifestyle choices

4. Stay proactive about your long-term health

Don’t wait until you feel “off” to get tested. Talk with your healthcare provider about adding these labs to your annual workup — or book a comprehensive wellness consult with a functional medicine provider who can interpret them for optimal health.