Conway McLean, DPM, Journal columnist

Let’s talk about toenails. Likely, it’s one of your favorite topics and then again, maybe not. If it were, the odds are good the discussion would be centered on the weird changes occurring to our nails, especially as we age. Most nail conditions have been studied and written up in the textbooks, appropriate since these nails can appear strange, bizarre, even grotesque. The years are hard on these (often) hidden appendages.

Nails are subject to significant physical injury during their lifetime, crammed into a shoe, or jammed suddenly and forcibly into some immovable piece of furniture. A majority of the global population have worn, at some point in their lives, shoes that are too short. Then you crowd them into this hot, sweaty container, aka a shoe, sometimes stiff and unyielding, and naturally there is pressure and stress to the nail plate and the nail root (the structure which grows the nail). If this structure is traumatized, even if it takes years, it can produce a progressively more distorted nail plate.

To those of you with healthy nails, you may be asking at this juncture, what can toenails possibly do? What oddities can develop in a nail? To that, the answer is…..you’d be amazed. Do you get scared at monster movies? Then don’t look at a medical text on diseased nails; you’ll get them confused since both will be horrific. Even a web search can produce frightening results.

Some of the changes possible to a toenail are more impactful, resulting in real disfigurement. How about a big toe in which the nail grows straight up, like a club, vertically from the toe? (Try trimming a nail like that!) Or a nail that curves so sharply, the tips of the nail meet in the middle. And the colors a nail can become, remarkable. A veritable rainbow of varying shades are seen.

One of the most frequently seen changes is thickening of the nail plate. Along with that, the nail can curl grotesquely, curving into the toe along the sides, eliciting obvious pain. The nail unit is well-endowed with nerve endings. Subsequently, nail problems can be quite symptomatic. But what do all these changes mean, what is occurring which produces such a radically altered appearance?

Ask anyone, be they a member of the public or a healthcare professional, if a toenail is discolored, or even slightly thickened, then it must be fungus. Without question, absolute certainty in their voices, the declaration is made. Unfortunately, this was disproven long ago and it is now well documented, even discussed in textbooks, numerous conditions cause changes to toenails, without the involvement of any fungus whatsoever.

One of the most common reasons that nails change and become discolored and misshapen is also a limb and life threatening condition. Every living tissue in the human body is dependent on that vital elixir, human blood. Without a sufficient supply, tissues change. This holds true for toenails as well. Fungal nails can cause some serious complications, but those aren’t typical. PAD, peripheral arterial disease, in contrast, is associated with an increased risk of limb loss or death.

An extremely common cause of nail changes, often attributed to fungus, is from trauma. We can probably all relate to the experience where a single traumatic event (the cliched hammer blow to the thumb) leads to a disfigured nail, forever. This resulted from trauma to the root of the nail, the structure which grows the nail. Modern medicine does not have the ability to straighten out a disturbed, altered nail root. But this same end-product may be the consequence of repetitive “micro-trauma,” in which pressure causes these changes, but gradually, over years.

Various scenarios lead to recurrent physical injury of a nail, from shoes without sufficient toe space to hammertoe deformities. Also important, the foot moves inside a shoe and this leads to repeated impact with the end or bottom of the shoe. Whatever the source of pressure, even a neighboring toe, the result will be progressive malformation of the nail root and plate. So, if it looks like a fungal nail infection, how is one to know it isn’t?

Psoriasis is an extremely common condition affecting millions of people, roughly 3% of the US population. And 80 percent of them have alterations in the appearance of the nail which are, once again, difficult to distinguish from a fungus. When this is the cause, there can be pitting of the nail, which is not often seen in a fungal infection. As should be expected, these are very resistant to treatment (not that fungal nail infections go away easily).

But that isn’t the only systemic disease potentially producing altered toenails. Certain lung diseases can cause yellowing of nails, also true for rheumatoid arthritis. Blue nails may be due to insufficient oxygen carried by the red blood cells, and a variety of afflictions can do that. Diabetes can lead to whitened toenails, as can liver disease. Many skin cancers arise from the nail unit, including malignant melanoma, but the changes are often missed. These melanomas have a high mortality rate, so don’t ignore dark spots or streaks.

The astute reader will have noted many apparent similarities between these pathologies and fungal nail infections. But no mention of how to differentiate between them, a true diagnostic dilemma. As an example, look at how many Americans have been prescribed a drug for these nail changes without any diagnostic studies, prescribing strictly by appearance. Yet, this drug is metabolized by the liver, with the (rare) potential to result in impaired liver function, which has been permanent.

Notice, to this point there has been no mention of fungal nail infections, which are epidemic. But studies have revealed these explain nail changes only 50% of the time. Half the time some other phenomenon is at work. Thus, logically, any nail fungus treatment will have little chance of significantly improving the health and appearance of an abnormal nail not afflicted with fungus. And if it is fungus, the longer you wait (to treat), the less effective your treatment.

As you may imagine, the gold standard for determining the reason a nail has changed is biopsy. Without, it’s just conjecture and guesswork. Getting the right material for analysis, performing the removal of an appropriate section of nail painlessly and without disfiguring the nail, all are important and require some expertise. But the concept is nearly universal in dermatologic medicine: if you want an accurate diagnosis, get a piece, and send it to a pathology lab specializing in this kind of specimen.

It should be obvious that nail changes develop, over time, for a host of reasons. Now you know it is inaccurate to assume these changes are always fungal. Don’t waste your time applying some OTC fungal nail medicine to your discolored toe for the next year if you don’t know what it is. Besides, these are ineffective even when it is a fungus. And don’t waste time not getting a timely diagnosis for your nail changes!

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula. Dr. McLean’s practice, Superior Foot and Ankle Centers, has offices in Marquette and Escanaba, and now the Keweenaw following the recent addition of an office in L’Anse. McLean has lectured internationally, and written dozens of articles on wound care, surgery, and diabetic foot medicine. He is board certified in surgery, wound care, and lower extremity biomechanics.