Nail Fungus Lab Tests

When a physician suspects that a patient has a finger- or toenail infection caused by a fungus (onychomycosis), he or she will frequently want to send a sample for nail fungus lab tests. This is important because a variety of different nail conditions can look similar to onychomycosis but are actually caused by something else. Harmless bacterial colonization appears as a discoloration of the nails, and even keratin debris, a buildup of dead skin cells under the nail, can look like the start of a problem. There are also a number of systemic diseases that make nails look bad. It’s important to know what you’re dealing with before you try to treat it.

A typical sample for onychomycosis testing is clippings or fillings, or if the nail is starting to flake and come apart, a collection of flakes and crumbly bits. The patient can usually collect the sample themselves and take it with them to an appointment, as long as they collect it and store it in a clean and hygienic manner (Note that some labs may not accept specimens collected at home for nail fungus lab tests, so ask first).

Use a clean pair of nail clippers, scissors, or nail file – preferably something that has not been used by anyone else, or at the least, that has been thoroughly washed. Onychomycosis testing doesn’t require a large specimen, but collect at least a sixteenth of a teaspoon if possible. Place the sample in a clean container – again, it’s important that the container has been thoroughly washed because a dirty container may already contain environmental fungal spores and nail fungus lab tests can be invalidated by contamination. The sample is not very perishable, but take it within a day or two of seeing your physician.

In the lab, onychomycosis testing has several stages and may differ from place to place. Generally a quick examination for fungal elements using a microscope gives a rapid preliminary result. Then the sample is planted on culture media and incubated. Some fungi take weeks to grow, even in laboratory conditions, so don’t be surprised if you have to wait a month or longer for the results of your nail fungus lab tests. If something does grow, laboratory staff will do extra testing to determine the fungal species so that your doctor knows whether your treatment is the right one.