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What your fingernails say about your health

25/4/2023

Translation: Katherine Martin

Gleaming nails mean a gleaming bill of health. But what if your fingernails noticeably change? Unsightly ridges or discolouration could be harmless – or they could be warning signs of an illness.

Time for a little look at our fingernails. What do you see when you look at your unpainted nails? If they have a pale pink shine, gently curve upwards, grow evenly and smoothly, have a recognisable moon shape at the base and don’t immediately break with any slight movement, you’ve reason to be pleased. This is, after all, how Dr Sabine Schwarz, specialist in dermatology and head of the renowned Hautzentrum Wien, defines healthy fingernails. Unfortunately, though, the diagnosis reached via visual inspection isn’t always quite so positive. Nails can develop ridges, stains, discolouration, cracks or even deformations.

You can, of course, counteract these changes with the help of a manicure set, some nail polish and nailcare tips. The thing is, you might be missing a vitally important message your body is sending you. Changes in the colour, shape and surface of your nails can be a warning sign for symptoms of a nutritional deficiency, circulatory disorders and hormonal changes, or even serious organ diseases.

Distrupted nail growth

The background to all this is that your nails are made of keratin, a horn-like substance constantly produced by the skin cells. However, if you’re deficient in certain vitamins, nutrients or minerals, have circulatory issues or are ill, nail growth can be disrupted. «When the body comes under a lot of strain, it tries to manage its resources. As a result, it temporarily slows down nail growth. Instead, it only forms a thinner layer of a horn-like substance, which, for example, forms ridges. Once the illness regresses, there’s a nail growth spurt. However, it can take up to six months for the affected areas to grow out again,» says Sabine Schwarz.

Since nails only grow very slowly (an average of 0.8 millimetres per week), these changes won’t make themselves apparent until you’ve recovered – or if you’re experiencing a long-term health problem. This is exactly why you should take changes in your nails seriously. «If your nails change permanently, noticeably and visibly and the change can’t be attributed to previous injuries, lifestyle or known pre-existing conditions, a doctor should clarify what’s causing it,» says Dr Schwarz.

Nail changes don’t always clearly point to a particular cause or illness. «However, doing a blood test to reveal vitamin and hormone deficiencies, for example, quickly provides clarity in 80 per cent of cases. Following that, you can take the appropriate steps and medications to counteract them.»

Issues with metabolism or organs

«There are numerous metabolic issues and organ diseases that can lead to nail changes. As well as diabetes mellitus, these include thyroid, kidney and liver diseases,» says Schwarz. Nails which lose their lunula (the little moon at the base) or Terry’s nails (link in German) could indicate liver cirrhosis. Terry’s nails can also be caused by diabetes. Cloudy and almost completely white in appearance, Terry’s nails have also been reported to result in splinter hemorrhages and nail detachment.

Thyroid disease may also cause the nail to detach from the bed. This might also be accompanied by a thickening or thinning of the nail plate. An overactive thyroid presents as brittle nails and grey discolouration. Chronic kidney disease, however, characteristically results in Lindsay nails, also known as half-and-half nails. Lindsay nails can be spotted due to a pink, red or brown band running along the nail bed toward the fingertips.

Dark spots on nails

Discovered blue or black spots under your nails? If you know it isn’t a bruise, get yourself to the doctor. The reason? If you don’t remember injuring yourself or if the spot doesn’t shrink, «dark spots or narrow, dark strips reaching the fingertip could be due to melanoma,» Schwarz says.

According to a study (in German), up to 3.5 per cent of skin cancer malignancies occur under a nail, with the thumb and big toe being most frequently affected.

Nail clubbing and spoon nails

Bulging nails with a deformed, round shape are referred to as watch glass nails or nail clubbing, though this does tend to be rare. «This nail deformity can occur in people with diseases of the heart, lungs, intestines or liver, or cystic fibrosis,» Schwarz says. Fortunately, however, most people with these illnesses are already receiving treatment for other symptoms before nail clubbing sets in.

In people with deficiencies in iron or other substances, psoriasis and infections, on the other hand, the nails often have the opposite of an upward bulge. Instead, the nail plate is flatter in the middle than at the sides – a phenomenon known as spoon nails. These, too, should be seen by a doctor.

Unhealthy skin, unhealthy nails

Not all nail changes are signs of diseases manifesting somewhere in your body. Sometimes, the nails themselves can be affected by tumours, often caused by inflammation or skin disease. The list (in German) of possible diagnoses accompanying nail changes is lengthy.

«Nails are skin appendages, so they’re also considered part of the skin. That’s why eczema or psoriasis can also change the appearance of the nails,» says Sabine Schwarz. One example of this is psoriasis vulgaris, which causes nail pits (indentations in the nail plate) in many patients. Not only that, but round, yellow or brownish spots known as oil spots may appear under the nail plate. In rarer cases, greyish-white scales also appear under the nail.

Take nail fungus seriously

The most common nail disease is fungal infection (link in German). This mostly affects the feet – the condition tends to be rare in fingernails. If you notice yellowish or greenish discolouration, wedge- or stripe-shaped thicknesses running vertically, or white, rough bumps on the top outer edge of your nail, you should have it examined.

After all, nail fungus can spread to your other nails and work its way into the deepest layer of the nail plate. If the fungal infection progresses, the nails become brittle before gradually disintegrating. Not only does this look unsightly, but it can also be painful, which severely limits the functionality of the affected toes or fingers.

«The fungal growth pattern can provide initial clues as to what type of fungus is involved. A piece of the infected nail generally needs to be examined by a laboratory, as different pathogens need to be tackled differently,» says Schwarz. Fighting the fungus regularly is key. Most importantly, it needs to be tackled for a long enough period, so the nails can be kept free of fungus permanently. With some topical remedies, this can take up to a year; with tablets or capsules, usually three months.

Causes of nail discolouration

Sometimes, rather than being caused by fungus, yellowish discolourations are simply «homemade». If you smoke, for example, don’t be surprised if your nails turn yellow. The same goes for anyone with a penchant for dark-coloured nail polish. Nail whitening polish or home remedies such as lemon can help with this kind of discolouration.

Other colour changes, on the other hand, aren’t purely cosmetic, and should be taken seriously. «For instance, pale, whitish nails can be a sign of iron deficiency or circulatory problems, while bluish staining can indicate heart or lung disease,» says Schwarz.

Seeing the colour green on your nails? You might have a bacterial nail infection. These are triggered by minor injuries, such as filing your nails too vigorously, overplucking your cuticles or pushing them back roughly. Sucking your thumb or working in contaminated water are also considered risk factors for infection, as they allow bacteria to find their way in through tiny skin wounds.

Get nail bed infections treated quickly

Speaking of infection, people often delay dealing with acute, bacterial inflammations of the nail bed, although they become noticeable quite quickly. If your fingertip is hot, swollen, hard and there is severe, throbbing pain, «it should be treated quickly with antibiotics to prevent the infection from spreading,» Schwarz warns. An abscess forming in the fingertip can also compress the surrounding tissue, causing it to die. Not only that, but bones, joints or tendons underneath can also be infected.

«Clouds» get the all-clear

Thankfully, not all nail changes are cause for concern. Small, white discolourations resembling clouds, for instance, are considered harmless. «They show up when there are tiny cavities between the nail and the nail bed,» Schwarz says. These tend to be caused by low-level impact against the nail root or over-manipulation of the cuticle. Even so, these «clouds» are no pretty sight, so you should only ever push back your cuticles carefully using a hoof stick or cuticle pusher.

Vertical ridges on the nail

The expert also gives verticle ridges the all-clear. These are usually a result of a genetic predisposition. With age, they become more frequent or more prominent, helped along by continuous lack of fluid. Drinking enough water can minimise the ridges. However, if their appearance bothers you, you can rub them away with a nail buffer. However, if the ridges are significantly deeper than those of your peers, they may indicate circulatory problems or rheumatoid arthritis.

Horizontal ridges on the nail

According to Dr Schwarz, you needn’t be worried about horizontal ridges either. Ridges running in this direction reveal more about your past than your current state of health. They occur when too much force has been applied to the nail, such as during an injury. Or they occur after periods of extreme stress or as a result of illness, such as gastrointestinal infections or high fevers.

If you haven’t been ill, stressed or injured, they can be indicative of a zinc deficiency, which can be tackled with zinc supplements or a zinc-rich diet. Good sources are beef, eggs, milk and cheese or whole grain products.

Other causes of nail changes

Basically, nail changes are common, regardless of age. They’re caused by a myriad of things, and aren’t always linked to disease or deficiency. Often, it’s your lifestyle or habits that aren’t doing your nails any good. «In addition to contact with cleaning products and chemicals, using nail polish and nail polish removers regularly, wearing false nails, or even the change of seasons can affect nail structure,» Schwarz says. When it’s cold outside, the nail plate contracts and the blood doesn’t circulate properly. In all these cases, «bad» nails are a purely aesthetic problem that can be tackled with a manicure.

Header image: Shutterstock

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Daniela Schuster

Autorin von customize mediahouse

oliver.fischer@digitecgalaxus.ch

If my job didn't exist, I'd definitely invent it. Writing allows you to lead several lives in parallel. On one day, I'm in the lab with a scientist; on another, I'm going on a South Pole expedition with a researcher. Every day I discover more of the world, learn new things and meet exciting people. But don't be jealous: the same applies to reading!

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