What Your Body Is Trying to Tell You: 14 Visible Signs, and Which Ones Earn a Test

Could that sign on your nails, skin or tongue be a deficiency?

Sometimes. A few signs carry real weight, and most have a more common, everyday cause.

Knowing which is which can save you money on the wrong supplement and point you to the right test.

Key Insight:

↳ A visible sign tells you where to look. A test tells you what’s actually going on.

↳ Three signs carry real weight: spoon-shaped nails, a smooth, sore tongue, and restless legs at night.

↳ Three of the most searched signs, white spots, vertical ridges and eye twitches, rarely point to a deficiency.

Why It Matters:

↳ Visible signs make easy ads, and the wrong answer usually comes with something to sell.

↳ Nutrient signs tend to show up late. A nail takes months to grow out what happened inside you.

↳ A normal blood panel is a separate question. A nutrient can look fine in your blood and still run short inside your cells. Here’s why.

The 4 Rules Before You Buy Anything:

↳ A sign is a reason to test, not a conclusion. Each sign below has a more common everyday explanation.

↳ Signs show up late. Not having one doesn’t rule anything out.

↳ Check the myth before you buy. White spots, ridges and eye twitches drive a lot of supplement spending, with little behind it.

↳ Two signs together mean more than one. A sore tongue plus cracks at the mouth plus fatigue is a pattern. One split nail is a split nail.

Nails:

↳ White spots. Usually a knock to the nail weeks ago. Nails grow about 3 mm per month, so you can count back to it. The zinc and calcium story doesn’t hold up. Ask for: nothing, unless the whole nail bed turns white or bands cross every nail.

↳ Spoon-shaped nails (koilonychia). A real, well-known sign of low iron. Ask for: ferritin with CRP, a CBC and transferrin saturation. New low iron in a man, or after menopause, is a reason to find the cause.

↳ Vertical ridges. Usually age, like lines on skin. Ask for: nothing, unless it’s one nail, a deep ridge or a dark streak. Those go to a dermatologist.

↳ Horizontal grooves across all your nails (Beau’s lines). Your nails paused growing during an illness, a high fever or severe stress, and the groove’s position roughly dates it. Ask for: a mention to your clinician, especially if it’s on all 20 nails.

↳ Brittle, peeling nails. Usually water: washing, sanitizer, acetone and gel polish. Iron and thyroid are worth a test. Ask for: ferritin with CRP and TSH with free T4. Then try dish gloves, which help more people than biotin.

Mouth and Tongue:

↳ Cracks at the corners of your mouth (angular cheilitis). Can point to low riboflavin, B6, B12, folate, iron or zinc. More often it’s lip licking, cold weather or dentures that no longer fit. Ask for: a CBC, ferritin with CRP, B12, and zinc with copper and CRP. Bloodwork clean? An antifungal often helps more than a vitamin.

↳ A smooth, shiny, sore tongue (atrophic glossitis). This one carries real weight, B12 especially. Ask for: B12 with methylmalonic acid, RBC folate, ferritin with CRP and a CBC. Tingling or balance trouble too? Say so, because it changes the urgency.

↳ Canker sores that keep coming back. Linked to low iron, B12, folate and zinc, though stress, a bitten cheek, sodium lauryl sulfate in toothpaste and food triggers are more common. Ask for: ferritin with CRP, B12, RBC folate, zinc with copper, and a celiac test if they’re frequent.

Hair and Skin:

↳ Hair shedding. Often starts about 3 months after a trigger like illness, surgery, childbirth, rapid weight loss, a new medication or serious stress, and it usually settles. Ask for: ferritin with CRP, a CBC, TSH with free T4, and zinc with copper. Then think back 3 months.

↳ Bruising easily. Can mean low vitamin C or K, or low platelets. More often it’s thinner skin with age, sun damage, and medications like aspirin, blood thinners, NSAIDs and steroids. Ask for: a CBC with platelets, and bring a list of everything you take. Big bruises with no injury, bleeding gums or nosebleeds? Call this week.

↳ Dry, bumpy skin on the backs of your arms (keratosis pilaris). Common, largely genetic and harmless. Less often it’s low vitamin A or essential fats. Ask for: nothing routinely, unless you also have celiac, trouble absorbing fat, or night vision trouble.

Your Whole Body:

↳ Always cold, especially your hands and feet. Low iron and low thyroid are both real and testable. Often it’s circulation or body build. Ask for: ferritin with CRP, a CBC and TSH with free T4.

↳ Restless legs at night. One of the strongest iron connections there is. Sleep guidelines use ferritin at or below 75 ng/mL, or transferrin saturation under 20%, as the trigger to treat with iron. Ask for: ferritin and transferrin saturation on a fasting morning draw, and say “restless legs.”

↳ An eye twitch that won’t stop. Usually sleep debt, caffeine, screens or stress. The magnesium idea has very little behind it. Ask for: nothing first. Sleep, cut caffeine, and see if it stops. If it spreads or lasts weeks, see a neurologist.

Why This Isn’t Everywhere:

↳ Signs like these sit between specialties. The nail belongs to dermatology, the ferritin to a primary care panel, and the sign that connects them belongs to neither appointment. That’s how care is divided, not a gap in anyone’s effort.

Why It’s a Win-Win I Wanted to Surface:

↳ You stop paying for supplements that won’t help, and start with the test that might.

↳ Your clinician gets a specific, answerable question instead of a long list.

↳ Your household gets your energy back sooner, plus the money that was going to the wrong bottle.

We Actually Have a Book on This

What Your Body Is Trying to Tell You, in the reference section of The Root Cause of Your Symptoms, Uncovered, covers each sign: what it can mean, what it usually means, and what to ask for. Chapter 11 maps common symptoms to the first tests worth ordering.

Learn more about the book

Where the Numbers Come From

↳ Restless legs thresholds: International Restless Legs Syndrome Study Group, 2018 and American Academy of Sleep Medicine guideline, 2025. The AASM notes these consensus thresholds haven’t been tested in trials.

↳ Everything else: The Root Cause of Your Symptoms, Uncovered, 2nd edition, reference section and Chapter 11.

↳ Educational content. Keryn Gold holds a PhD in Biomedical Sciences, not a medical license. Not medical advice.

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If you could get one clear answer about your body this month, what would you ask?