8 Surprising Health Issues Your Dermatologist Can Spot (That Have Nothing to Do With Skin Cancer)

While the saying, "don't judge a book by its cover" applies to many things in life, it doesn't quite apply when it comes to your health. In fact, taking a closer look at your skin can actually tell you a lot about what's going on underneath it.

"The condition of your skin can sometimes be a reflection of your body's internal wellbeing," says Y. Claire Chang, MD, a board-certified dermatologist at Union Square Laser Dermatology in NYC. In fact, "your skin can be the first visible clue in diagnosing more systemic medical conditions."

Thankfully, your dermatologist can spot these issues at a regular checkup. From there, they can refer you to a specialist who can treat you.

The way your skin looks may actually reveal something about your gut.

"The connection between the gut and skin is often referred to as the gut-skin axis," which means your gut microbiome can affect your skin, Dr. Chang says.

In fact, an April 2022 review in ‌Biomedicines‌ found that an imbalance of gut bacteria may be associated with certain inflammatory skin conditions like atopic dermatitis, rosacea and psoriasis.

Certain GI issues like inflammatory bowel diseases (IBD) can also cause skin problems, too. Dr. Chang says about 10 to 30 percent of people with ulcerative colitis get skin issues. And 40 percent of people with Crohn's disease get skin issues from the condition, per the National Library of Medicine.

Skin problems that can result from Crohn's disease include the following, per Dr. Chang:

• Fissures (dry, cracked areas of skin that thicken over time)
• Ulcers or open sores on the skin
• Abscesses in perianal region (pus-fulled bumps near the anus or rectum)
• Mouth ulcers
• Pyoderma gangrenosum (a rare skin condition that causes ulcers on the legs)
• Sweet's syndrome (a rare disorder that causes skin plaques, or raised red patches covered with a buildup of dead skin that looks like white scales)
• Metastatic Crohn's disease (a rare type of Crohn's disease that causes spots or plaques on the legs and arms)

Another potential skin symptom of IBD is erythema nodosum — a condition where raised, painful red nodules pop up on your shins, Dr. Chang says.

Some GI cancers are also associated with skin-related issues like hyperpigmentation (patches of darker skin) and thickening of the skin on the palms and soles of the feet, she adds. These conditions are rare, though.

If you're not drinking enough water throughout the day, your dermatologist can tell by the look of your skin.

Dehydration can cause dry, flaky and rough skin that may feel tight and uncomfortable, Dr. Chang says. Sunken skin around the eyes is another telltale sign of dehydration, per the AAD.

Your skin may also look dull if you aren't drinking enough water, worsening the appearance of fine lines and wrinkles, Dr. Chang adds.

So, how much water should you drink to help keep your skin healthy? The National Academies of Sciences, Engineering and Medicine recommends getting 11.5 to 15.5 cups of water per day, through drinking and eating water-rich foods, to keep your body hydrated.

Diabetes can affect many parts of your body, including the nerves and blood vessels of your skin, per the Centers for Disease Control and Prevention (CDC).

People with diabetes have a greater chance of getting dry, itchy skin or skin infections, per the American Diabetes Association (ADA). Unfortunately, these issues often create a vicious cycle: When you scratch dry skin, it can accidentally break open, allowing in germs and bacteria that cause infection.

On top of this, there are certain skin problems that only (or mostly) present in people with diabetes.

One is called acanthosis nigricans — a skin disorder caused by diabetes or insulin resistance where velvety, dark plaques show up in the folds of your neck, armpits or groin, Dr. Chang says.

Another is called necrobiosis lipoidica, which "causes red bumps to show up on your lower legs that turn into waxy or yellow-brown plaques," she adds.

Other diabetes-related skin conditions include the following, per the ADA:

• ‌Diabetic dermopathy:‌ benign light brown, scaly patches on the legs that are often mistaken for age spots
• ‌Diabetic blisters (bullosis diabeticorum):‌ painless sores on your lower legs and feet and sometimes arms and hands
• ‌Eruptive xanthomatosis:‌ small, reddish-yellow, itchy bumps on the back of your hands, feet, arms, legs and butt
• ‌Digital sclerosis:‌ tight, thick and waxy skin on your fingers that may cause stiff finger joints
• ‌Disseminated granuloma annulare:‌ a raised rash or a ring-shaped pattern of bumps across your body

Don't worry, though: Treating your diabetes and managing your blood sugar will help reduce your risk of getting these skin problems.

There are a few autoimmune conditions associated with skin changes. Your dermatologist can often spot some of these rashes and refer you to a specific doctor (rheumatologist, endocrinologist, etc.), especially if you're feeling other non-skin-related symptoms.

Some of these include the following, per Dr. Chang:

• ‌Systemic lupus erythematosus (SLE):‌ An autoimmune disease that affects multiple organs, including the skin. In fact, "four of the 11 criteria for an SLE diagnosis are skin-related, including malar rash (a red rash spread across the nose and cheeks in a butterfly shape), disc-like lesions, oral ulcers and sensitivity to light," Dr. Chang says. 
• ‌Dermatomyositis:‌ An inflammatory condition that causes muscle weakness and skin rashes. You may also get, "a red or purple rash on your eyelids, chest or shoulders, scaly bumps on your joints or calcium deposits under the skin (which feel like bumps)," Dr. Chang says.
• ‌Scleroderma:‌ A rare autoimmune disease that causes hard, tight skin and other organ issues. Sometimes, you can get red patches across the body. You may also have broken capillaries that appear on your skin, red, blue or white fingers and toes from Raynaud's phenomenon or calcium bumps under the skin, Dr. Chang adds.
• ‌Grave's disease:‌ An autoimmune disorder that can cause hyperthyroidism (overactive thyroid). You may also get warm, moist and flush skin, protruding eyes, hair loss, excess sweating and red-brown lumps on the legs (called pretibial myxedema), plus discoloration of the skin and nails.
• ‌Hashimoto's disease:‌ An autoimmune disorder that can result from hypothyroidism (underactive thyroid). You can get pale, cold and dry skin, brittle hair and yellow-tinted palms and soles, Dr. Chang says. 
• ‌Dermatitis herpetiformis:‌ A chronic autoimmune condition that's related to celiac disease. About 10 to 25 percent of people with celiac disease develop this rash, which includes itchy bumps and blisters across your body, according to the Cleveland Clinic.

If you think you have an autoimmune condition, or have already been diagnosed with one and get skin issues later on, talk to your team of doctors to figure out how to treat your skin symptoms.

Sometimes acne and other skin issues means you have a hormone imbalance. Some conditions that cause hormonal acne and skin problems include the following, per Dr. Chang:

• ‌Polycystic ovary syndrome (PCOS):‌ In addition to irregular menstrual cycles, ovarian cysts and weight gain, people with PCOS often have acne or excess facial hair growth (called hirsutism), Dr. Chang says.
• ‌Cushing's syndrome:‌ Caused by too much of the stress hormone cortisol. You may get thin skin, acne, excess facial hair, bruising and hyperpigmentation.
• ‌Addison's disease:‌ Caused by a lack of the adrenal hormones cortisol and aldosterone. One possible symptom is hyperpigmentation of skin folds, elbows, knees and scars.
• ‌Acromegaly:‌ In addition to excessive growth hormone and enlarged hands and feet, people with acromegaly can have changes in facial features and thickened skin.

If your acne is accompanied by other symptoms, ask your dermatologist to refer you to someone who can help, like an endocrinologist or gynecologist.

Some people with high cholesterol will get small yellow bumps around their eyes — a condition called xanthelasma, per the Cleveland Clinic. While it's most often caused by cholesterol, it can also be from diabetes or hypothyroidism, per Dr. Chang.

Sometimes, you can get these small bumps without an underlying cause. Still, it's better to be safe and see your doctor for blood work, to rule out anything serious.

A diet lacking in vitamins and minerals can negatively affect your health in many ways, including your skin.

"Nutrient deficiencies can lead to various changes in your skin's appearance and texture," Dr. Chang says. Here are just a few examples of deficiencies and their skin symptoms, per Dr. Chang:

• ‌Vitamin C deficiency:‌ bruising, bleeding gums, slow wound healing, brittle hair and petechiae (tiny, round spots that form on your skin)
• ‌Vitamin A deficiency:‌ dry, rough and flaky skin or red-brown bumps across your body
• ‌Riboflavin (vitamin B2) deficiency:‌ intertrigo (a widespread, red rash), and a swollen tongue and lips
• ‌Niacin (vitamin B3)‌ ‌deficiency:‌ dermatitis; a red sunburn-like rash on the face, neck and chest; a "Casal necklace" (i.e., a distinct rash around the neck, per the Cleveland Clinic) and fissures
• ‌Vitamin B12‌ ‌deficiency:‌ hyperpigmentation, hair changes and a cracked mouth and lips
• ‌Iron deficiency:‌ pale skin and thin, spoon-shaped nails (also called koilonychia, per the Cleveland Clinic)

Your primary care doctor can do blood work to see if you have any nutrient deficiencies, especially if your dermatologist points out a specific skin problem.

Changes in your skin's color can also be a sign of underlying kidney or liver disease. Both of these organs work to eliminate waste from the body, per the National Kidney Foundation and Johns Hopkins Medicine. And when they aren't working properly, it shows.

"Kidney disease can cause many different skin and nail changes, like dry skin, itching, a white color on the upper part of the nails and white bands across the nails," Dr. Chang says.

Other skin issues associated with chronic kidney disease include the following, per Dr. Chang:

• ‌Calciphylaxis:‌ calcium deposits in your blood that interrupt blood flow to your skin
• ‌Acquired perforating dermatoses:‌ severely itchy, tiny bumps on the limbs
• ‌Porphyria cutanea tarda:‌ painful blisters on sun-exposed skin
• ‌Nephrogenic systemic fibrosis:‌ thickening of the skin

Likewise, "liver diseases like cirrhosis can lead to skin changes, including red palms, branching blood vessels, easy bruising and jaundice (a yellowing of the skin)," Dr. Chang says.

And if your skin looks gray-bronze, you could have hemochromatosis — an excessive amount of iron in your blood, per the Mayo Clinic.

Dr. Chang recommends seeing your dermatologist at least once a year to get a full-body skin exam. There, they can check for any suspicious skin issues (including early signs of skin cancer) and get clues about your overall health.

If you notice any sudden or unexpected changes in your skin, it's worth calling your dermatologist to schedule an appointment sooner than your yearly checkup.