Dear Doctor: I had a rough spot on the back of my hand that turned into a wart. What caused it? How do I get rid of it?

Dear Reader: You’re describing what is known as a common wart. It’s a small, raised skin growth caused by one of the estimated 150 different varieties of the human papilloma virus, or HPV. Other types of HPV cause different kinds of warts. These include plantar warts, which are callouslike growths on the soles of the feet; genital warts; and smooth, flat-topped growths known as flat warts, often seen on the face and forehead.

Common warts don’t present any health dangers. However, they can be unsightly and cause embarrassment. They’re typically about the size of a pencil eraser or smaller, may be circular or oval, and can appear anywhere on the body. Common warts may grow a smooth, domed top, or they can have a wrinkled appearance, like a head of cauliflower. They’re often a different color than the surrounding skin, including brown, gray, pink or beige. Some may contain what look like small black dots, which are actually tiny blood vessels filled with clotted blood.

If you get a common wart, you’ve come into physical contact with the virus that causes it, either on someone’s skin, or on a surface an infected person has touched. The virus can enter the body through a break in the skin, and if your immune system can’t fight it off, a wart will soon appear. Common warts are painless, but when they crack, or if you pick at them, they can bleed.

In most cases, your body’s immune system will rally, and the wart will eventually vanish, usually within a year or two. Those who would rather not wait have several treatment options. Most people can try over-the-counter wart medications available at the drug store. These are made up of salicylic acid, which is delivered either as a gel, liquid or in a patch. The acid gradually removes the layers of skin until the wart is gone. It’s helpful to soak the wart in warm water prior to applying the salicylic acid, as it will allow the medication to penetrate deeper into the many layers of tissue. In between treatments, use an emery board or pumice stone to remove the dead skin. Be sure to isolate these tools since they can transmit the virus. Side effects of this treatment can include skin irritation and discomfort. Never use salicylic acid on the face or on the genitals. People living with neuropathy or diabetes should not try at-home wart removers and should see a doctor instead.

If you try a home-based treatment and it’s unsuccessful, your doctor also has several options available. One is that same salicylic acid, but in a higher concentration, which requires a prescription. Another approach is cryotherapy, which uses liquid nitrogen to freeze the wart. Warts may also be removed with a laser, burned off or cut away.

Any time that a wart changes shape or color, or if it becomes painful or infected, it’s important to seek medical attention.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My 5-year-old grandson craves lead paint and has used his toothbrush to get at old layers of lead paint in his family’s renovated 1880s home. His development has slowed, and people think he’s autistic. If it’s the lead, what can we do?

Dear Reader: Your question covers several issues. We don’t make diagnoses in this column, so we would just note that the impulse to eat nonfood items -- such soil, chalk, clay or lead paint -- can be a disorder known as pica. The cause of these persistent cravings isn’t known, but pica has been associated with certain nutritional deficiencies, and with certain mental health conditions. The disorder can lead to serious complications, including intestinal blockage, parasitic infection and lead poisoning.

The United States government banned lead-based paints for residential use in 1978, but it remains a hazard in millions of older homes. Lead is a heavy metal that our bodies can’t use. When ingested, it interferes with numerous metabolic processes, including the production of red blood cells, absorption of calcium for bone and tooth development, and the proper functioning of the liver, kidneys, blood vessels, immune system, nervous system and the brain.

Lead is particularly harmful to the developing bodies and brains of babies, children and adolescents. In high amounts, it can be fatal. Even low levels of lead have been linked to impaired or delayed physical development, low IQ, learning disabilities, and emotional and behavioral problems.

Lead is a cumulative toxicant, which means it builds up in the body over time. As a result, symptoms of lead poisoning can take months or even years to appear. These include loss of appetite, abdominal pain, nausea and vomiting, chronic constipation, hearing loss, problems with vision, persistent fatigue, weight loss, tremors or seizures, irritability and the developmental delay that you report in your grandson.

Since you know your grandson has been eating old paint, it’s important to learn his blood levels of lead as soon as possible. Your family doctor can do this with a simple blood test. Blood levels of lead are measured in micrograms per deciliter, or mcg/dL. Levels as low as 5 mcg/dL are considered potentially unsafe and call for continued screening. It’s also crucial to find and eliminate all potential sources of lead in his environment. In older homes, deteriorating lead-based paint not only chips and flakes, it gives off contaminated dust that is easily inhaled.

In severe cases of lead poisoning, chelation therapy may be recommended. Although it can lower the levels of lead in the blood and soft tissues, it has not been shown to reverse the existing effects of lead poisoning. In this treatment, the child is given a medication that binds to the lead in the blood and soft tissues. It then forms a compound that can be excreted in the urine. Depending on the type of medication used, chelation therapy may be delivered orally or via an injection. Side effects can include headache, nausea or vomiting, and discomfort at the injection site. Chelation therapy should always be carried out under medical supervision, and only with prescription drugs.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My brother-in-law thought he had the flu, but it turned out to be Guillain-Barre syndrome. He’s now in his fifth month of an intense recovery. What can you tell me about the disease?

Dear Reader: Guillain-Barre syndrome is a rare disorder that affects about 1 in 100,000 people each year. It’s an autoimmune disease, which means the immune system goes a bit haywire. It mistakes cells within your body as threatening invaders and sets out to destroy them. In Guillain-Barre, the immune system attacks the peripheral nervous system, which encompasses all of the nerves in the body other than the brain and spinal cord. Infection with certain viruses and bacteria is a known trigger of Guillain-Barre, and is responsible for up to two-thirds of all cases.

Damage to the nerves results in weakness and exhaustion, often accompanied by tingling or pinprick sensations in the extremities. In the early stages of Guillain-Barre, people experience a loss of coordination that can impair balance, movement, speech, swallowing, vision and bladder control. These initial symptoms, along with possible abnormal blood pressure, both high and low, evolve over the course of the first few weeks. Progressive muscle weakness affects both sides of the body and occurs rapidly, often within hours or days. Severe cases of Guillain-Barre syndrome affect the patient’s ability to breathe and result in near-complete paralysis.

Diagnosis relies largely on a person’s symptoms. However, blood tests to measure red blood cells, white blood cells, platelets and hemoglobin, and metabolic panels to determine levels of electrolytes, blood sugar, total proteins and metabolic waste products, may be used to rule out other conditions. Guillain-Barre can cause certain changes to spinal fluid, so a lumbar puncture, also known as a spinal tap, may be ordered. Tests to measure nerve function can also be useful.

There is no known cure, so treatment consists of addressing existing symptoms, which is known as supportive care. This includes blood therapies such as plasma exchange, or plasmapheresis, which “cleans” the blood, or immunoglobulin therapy, which uses antibodies to try to calm the immune system. Patients often experience significant pain, which can be eased with medication. Since prolonged inactivity can lead to blood clots, compression garments and blood thinners are prescribed often. In serious cases, when swallowing or breathing are compromised, a feeding tube or a ventilator may be needed.

Most patients recover completely. However, as in the case of your brother-in-law, it’s often a gradual process. A lucky few are up and about in just a few months, but the majority of patients take about a year to fully recuperate. It’s also possible for recovery to take several years, and for patients to experience ongoing neurological issues.

Rehabilitative care includes physical, speech and occupational therapy. It can be a tough road back to good health, and many patients and their caregivers find a support group to be helpful. You can find more information at the Guillain-Barre Syndrome Foundation’s web site at gbs-cidp.org.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)