Is this black toenail fungus or a bruised toenail from running?

I have been training for a trail run and have been running on lots of hills in Marin. I recently noticed that I was getting some dark black discoloration of my toenail. I am worried that this might be black toenail fungus infecting the toenail. How can I tell whether the toe is bruised or if I really have a toenail fungus infection? Also, what if anything should I do to treat the black toenail if it is infected?

Thanks,
David, Mill Valley, CA


Black toenails are likely one of the most common injuries I see in runners in Houston and San Francisco. There can be a couple of causes of black toenails from running.

Differences between a bruised toenail and a fungal toenail:
A bruised toenail hurts because 1) there is bruise 2) there is blood under the toenail increasing pressure between the toenail and underlying nail bed. This causes pain in the toenail when you press on it or bump the toenail on the inside of your shoes. Fungal toenails are not usually tender unless the toenail infection has been present long enough to make the fungal nail really thick.  The increased thickness can cause some tenderness, but it doesn't happen quickly.

A bruise comes on quickly, but a toenail fungus infection appears gradually. Bruising will appear within a day or two of your long run, race or whatever injury to the toenail. If you kick a coffee table once with your toe, the toenail may develop a bruise and turn black. If you bump the toe inside your running shoe repeatedly while running down hill (or because the running shoes are too tight) you can also get a bruised black toenail from the cumulative trauma. This can happen overnight.  You wake up and the toenail is black.

The changes in the toenail caused by toenail fungus happen very slowly. The color of the toenail will not change quickly.  The increased thickness, yellow discoloration, white crumbly appearance and dark color of a fungal toenail infection happens so slowly that it is almost hard to notice.

You can learn more about black toenails and toenail fungus treatment here by reading about an example of a black toenail in Houston that actually is just a toenail bruise. You can also read about from runners, blisters and black toenails here.  Learn how a bruised toenail can lead to a toenail fungus infection.

Dr. Christopher Segler, Doctor of Podiatric Medicine is Board Certified, American Board of Podiatric Medicine. He is a 10-time Ironman finisher and marathon runner. He lectures frequently to other podiatrist and foot specialists at medical conferences on the treatment of complicated running injuries and running biomechanics. He is licensed to practice podiatry in Texas, California, and Hawaii. He travels back and forth between Houston and San Francisco to see injured runners who have running injuries that need the fastest treatment based on a runner's goals and running doc perspective. If you live in San Francisco or Marin and have a running injury question call 415-308-0833 to speak to him. If you are in Houston and have a question about a running injury, call him directly at 713-489-7674. 

What is the Best Way to Diagnose Gout in the Big Toe Joint?

An attack of gout that affects your big toe joint may be one of the most painful conditions you can have in your foot. When gout strikes, you get pain, redness, swelling and extreme tenderness...usually in the big toe joint. If you think you have gout, you probably want to make sure that you get the right diagnosis. Getting the correct diagnosis is important for two reasons.

1. You want to make sure you get the best treatment as quickly as possible.
2. You don't want to have to change your diet and start the dreaded gout diet unless you're absolutely certain that you actually do have gout.

Gout is actually caused by uric acid crystals accumulating in the foot. The crystals actually get deposited as the precipitate out of your bloodstream and become embedded with in the big toe joint, a bursa, or even within the tendons near the joint at the base of the big toe.

There are 5 ways to diagnose gout in the foot
1. Physical exam by a podiatrist
2. X-rays of the foot
3. Blood tests to look for high uric acid levels
4. Joint fluid analysis from the big toe joint
5. Cytology (fluid analysis under a microscope)

This video, posted by San Francisco's Housecall Podiatrist, discusses all of the ways in which your doctor can arrive at a diagnosis of gout. Because gout is a condition in which uric acid crystals actually get deposited in the soft tissues of your foot in your big toe joint, it is important to actually identify those crystals in order to accurately make the diagnosis of gout.

Physical exam (even by a podiatrist) is not 100% accurate simply because gout also mimics other conditions such as an infection in the soft tissues around big toe joint, infectious arthritis of the big toe joint, or even conditions that affect diabetic patients such as Charcot foot, where the foot bones start to break. All of these conditions can present themselves with redness swelling and extreme pain around the big toe joint. Physical exam by itself is just not the best way to diagnose gout.

Foot X-rays are almost always performed in a doctor's office when you have a red hot swollen foot in order to make sure that you don't have a dangerous infection or a fracture in the foot that could be just appearing like it is gout. But x-rays of the foot won't typically show much when an attack of gout has recently started.

Blood tests in order to determine whether or not you are one of the patients that has a high level of uric acid in their bloodstream (and more prone to gout) are not really effective at determining whether or not the pain and swelling around your big toe joint is really caused by the crystals in your joint. In fact, often times these tests are negative, misleading doctors to think that you might not have gout.

A more reliable way to determine whether or not the pain in the big toe joint it's actually caused by count crystals is to perform a joint aspiration where the fluid is removed from the joint to see if there is any chalky white material that looks like collections of gout crystals. This is much more reliable than physical exam, foot x-rays, or even blood tests.

But by far the most reliable way to make the diagnosis of gout is through cytology. This is where your doctor takes the joint fluid that was removed through joint aspiration and then sends it to the pathologist so that they can look for the actual gout crystals under a polarized light microscope. If you do have an attack of gout that is causing the pain in your big toe joint, the pathologist will be able to see needle shaped uric acid crystals within the joint fluid. This is a 100% accurate method of diagnosing gout in the foot.

Dr. Christopher Segler is an award-winning foot and ankle surgeon and sports medicine podiatrist practicing in the San Francisco Bay area. He provides housecalls for people with gout in San Francisco, Marin, Mill Valley, Tiburon, Oakland, Berkeley and Palo Alto. To learn more about the causes and treatment of gout in the big toe joint, visit the gout information page at www.AnkleCenter.com. if you would like to learn about how to get the fastest treatment possible for gout, you can learn more at www.DocOnTheRun.com.