What do hsCRP, ferritin and homocysteine tell you?

Most men know about cholesterol and testosterone. Far fewer know about high-sensitivity C-reactive protein, ferritin, and homocysteine. These three markers sit quietly in the background of the panel, and they can change how a clinician writes a plan. None of them are exciting. All of them are useful.

This is the working guide to the inflammatory and metabolic markers that move with age.

hsCRP: chronic inflammation

High-sensitivity C-reactive protein measures low-grade inflammation in the body. CRP is made by the liver in response to interleukin-6 signaling. The "high-sensitivity" version of the test is calibrated to detect the small elevations that matter for cardiovascular risk, not the large ones that show up during acute infections.

The reference framework:

• Under 1.0 mg/L: low cardiovascular risk.
• 1.0 to 3.0 mg/L: intermediate risk.
• Over 3.0 mg/L: high risk, roughly a doubling of cardiovascular event probability independent of cholesterol.
• Over 10 mg/L: likely active infection or acute inflammation. Re-draw after symptoms resolve.

The signal is independent of LDL and ApoB. Two men with identical lipid panels and divergent hsCRP have meaningfully different cardiovascular trajectories.

What raises hsCRP

The common drivers in men aged 35 to 55:

• Visceral fat. Adipose tissue around the organs is metabolically active and secretes inflammatory cytokines.
• Periodontal disease. The mouth is closer to the cardiovascular system than most people realize.
• Sleep apnea. Untreated OSA is one of the most reliable hsCRP drivers.
• Chronic poor sleep, even without apnea.
• Smoking and heavy alcohol use.
• Autoimmune disease. Worth ruling out when hsCRP is persistently elevated without an obvious driver.

What to do when hsCRP is elevated

Reread the panel for the metabolic context. Visceral fat reduction (resistance training plus a sustainable calorie deficit) is the single most effective lever for most men. Sleep apnea screening is high-yield in men with a thick neck, snoring, or daytime fatigue. A statin, when otherwise indicated for lipid management, also reduces hsCRP. Omega-3s help a small amount. Periodontal cleanup helps more than people expect.

Ferritin: iron status and inflammation in one number

Ferritin is the body's iron storage protein, and its blood level reflects total iron stores. It is also an acute-phase reactant, meaning it rises in inflammation. One marker, two jobs.

The reference framework:

• Under 30 ng/mL: iron deficiency, regardless of hemoglobin.
• 30 to 100 ng/mL: functional sufficiency for most men.
• 100 to 300 ng/mL: normal but worth context.
• Over 300 ng/mL: investigate. Either chronic inflammation or hereditary hemochromatosis.

Low ferritin

Iron deficiency in men is almost never dietary. The default workup is gastrointestinal blood loss, frank or occult. Endurance athletes can run low ferritin from foot-strike hemolysis and gut iron loss in training, but they are the exception. Most men under 30 ng/mL warrant a GI evaluation.

High ferritin

The dual nature of ferritin makes this the more interesting direction. Elevated ferritin with elevated hsCRP usually points to inflammation rather than iron overload. Elevated ferritin with a normal hsCRP, especially in a man of Northern European descent, raises the question of hereditary hemochromatosis.

When ferritin is over 300 with no inflammation, the next step is a transferrin saturation. Over 45 percent triggers HFE gene testing. A diagnosis at 35 prevents almost all of the damage that would otherwise show up at 55.

Homocysteine: B-vitamin and cardiovascular signal

Homocysteine is an amino acid intermediate in methionine metabolism. Elevated levels are associated with cardiovascular disease, cognitive decline, and venous thromboembolism. The mechanism is debated. The association is real.

The reference framework:

• Optimal: under 8 micromol/L.
• Acceptable: 8 to 12 micromol/L.
• Elevated: 12 to 15 micromol/L.
• High: over 15 micromol/L.

What raises homocysteine

The two most common drivers are B12 and folate insufficiency. Vitamin B6 plays a smaller role. The MTHFR gene polymorphism, common in the general population, impairs the conversion of folic acid to its active form. Hypothyroidism and renal disease also push the number up.

What to do when homocysteine is elevated

Check B12 first. Levels under 400 pg/mL are functionally low even when "in range." Methylated B12 and methylfolate, taken together, often normalize homocysteine within 8 to 12 weeks. The harder question, whether lowering homocysteine actually lowers cardiovascular events, is unresolved. The cleaner answer is that elevated homocysteine is a flag to look harder at the B-vitamin status and the broader cardiovascular picture.

How to read the cluster

A single elevated marker is interesting. The cluster is diagnostic. The most common patterns:

• High hsCRP plus normal ferritin and homocysteine: look at visceral fat, sleep, and periodontal disease.
• High hsCRP plus high ferritin: inflammation is real, search for the driver. Hemochromatosis is lower on the list.
• Normal hsCRP plus high ferritin: hemochromatosis workup, full stop.
• Normal hsCRP plus high homocysteine: B-vitamin workup, including B12, folate, and MTHFR if persistent.
• Three normal numbers: the rest of the panel is more informative.

The bottom line

The markers that move the protocol are not always the loudest ones. hsCRP, ferritin, and homocysteine are inexpensive, broadly available, and frequently informative. The reason most primary care visits do not include them is a combination of habit and reimbursement, not clinical judgment.

If you are running an annual panel, run these. The clinician who reads them well will catch the conditions that the standard physical was never going to find.