Body · lesson 4 of 11
Inflammation, vitamins, thyroid & the routine panels
hs-CRP, vitamin D, ferritin/iron, B12/folate, thyroid, and what CBC + CMP cover.
7 min read · reviewed October 2026
Beyond sugar and lipids, a handful of markers punch well above their weight — they're cheap, common, and frequently off in ways that are easy to fix. This lesson is your field guide to the high-value extras and the two routine panels almost every blood draw includes.
High-value extras worth knowing
High-sensitivity C-reactive protein — a general marker of low-grade, body-wide inflammation linked to cardiovascular and metabolic risk. It spikes temporarily with any infection or injury, so a single high reading during a cold means little; the chronic baseline is what matters.
The 25-hydroxyvitamin D test is the standard way to assess vitamin D status. Deficiency is extremely common, especially in winter and at higher latitudes, and it touches bone, immune, and mood health. Optimal targets are debated — ranges vary by guideline — so confirm what your lab and clinician use.
Ferritin reflects stored iron — but it's also an inflammation marker, so it can read falsely high when you're inflamed. That's why a full iron panel (iron, transferrin/TIBC, saturation) gives a truer picture than ferritin alone. Both deficiency and overload matter.
Key for nerves, energy, and red-blood-cell production. Deficiency is common in older adults, vegans/vegetarians, and certain medication users, and can cause fatigue or neurological symptoms that are easy to miss and easy to correct once identified.
TSH is the usual first-line screen for thyroid function; free T4 and free T3 add detail when TSH is off or symptoms don't fit. The thyroid sets your metabolic 'thermostat,' so problems here ripple into energy, weight, mood, and temperature.
The two routine panels
Most blood draws include two workhorse panels by default:
- CBC (complete blood count) — counts and characterizes your red cells, white cells, and platelets. It screens for anemia, signs of infection, and blood-cell abnormalities.
- CMP (comprehensive metabolic panel) — a broad chemistry panel covering kidney function (e.g. creatinine, BUN, eGFR), liver enzymes (e.g. ALT, AST), electrolytes, and fasting glucose.
Together they're a cheap, wide safety net — abnormalities here often surface a problem before any other marker does.
Context changes what a number means
Several of these markers are context-sensitive. hs-CRP and ferritin both rise with any acute inflammation, so testing during an illness can mislead. A 'high' reading taken while you're fighting a cold may simply be your immune system at work — retest when you're well before drawing conclusions.
Your ferritin comes back high. Why shouldn't you immediately conclude your iron stores are excessive?
- Ferritin is never accurate and should be ignored
- Ferritin is also an inflammation marker, so infection or inflammation can raise it independently of true iron stores
- High ferritin always means dehydration
- Ferritin only matters for athletes
Show the answer →
B.Ferritin is also an inflammation marker, so infection or inflammation can raise it independently of true iron stores
Ferritin is an acute-phase reactant — it climbs with inflammation, infection, or injury regardless of actual iron stores. That's why a full iron panel (iron, transferrin/TIBC, transferrin saturation) gives a more reliable read, and why timing and context matter when interpreting it.