The PPD medical abbreviation most often means purified protein derivative, the substance used in the tuberculin skin test that checks whether a person has been infected with the germ that causes tuberculosis. Many people simply call the whole test a PPD.
The same three letters have two other common uses. In a social history, 1 ppd means one pack of cigarettes per day. In obstetric and mental health notes, PPD can mean postpartum depression. The section of the chart, and the words around the letters, tell you which is meant.
At a glance
Stands for
Purified protein derivative (tuberculin)Other meanings
Packs per day (smoking history); postpartum depressionAlso called
Tuberculin skin test (TST), Mantoux testRead after
About 48 to 72 hoursMeasured as
Millimeters of firm swelling, called indurationBlood test option
Interferon gamma release assay (IGRA)Used in
Employee health, school entry, contact tracing, clinic screening
What the PPD medical abbreviation means in TB testing
Purified protein derivative is a protein extract taken from tuberculosis bacteria. A nurse injects a small amount just under the top layer of skin on the inner forearm, which raises a small pale bump. If the person's immune system has met TB bacteria before, it reacts over the next two to three days and the spot becomes firm and raised.
The test does not tell latent infection apart from active disease. A positive result leads to more steps, usually a chest X ray and a clinical review. Someone found to have active TB in the lungs may be placed on airborne ISO, meaning isolation, in the hospital.
How a PPD is read
The patient must return in about 48 to 72 hours. A trained person feels for induration, the hard raised area, and measures its width across the arm in millimeters. Redness alone does not count. Whether a size is positive depends on the person's risk.
| Induration size | Usually counted as positive for |
|---|---|
| 5 mm or more | People with HIV, recent close contacts of active TB, those on strong immune suppressing drugs, or with chest X ray changes |
| 10 mm or more | Recent arrivals from high TB areas, health care and lab workers, people in certain group living settings, young children |
| 15 mm or more | People with no known risk factors |
If the reading visit is missed, the test usually needs to be repeated.
Reading a PPD line in a chart
Employee health record: "PPD placed L forearm, read in 48 to 72 hrs; induration 0 mm, negative." The test went in the left forearm and no firm swelling formed, so it was read as negative.
You may also see TST, which means tuberculin skin test, or a note about a two step test. Two step testing repeats the skin test one to three weeks later for some adults starting jobs with regular screening, to catch a boosted response.
Skin test versus blood test
The interferon gamma release assay, or IGRA, checks a blood sample instead. It needs only one visit and is not affected by past BCG vaccination, which can cause a false positive skin test. Many clinics accept either. Your clinician picks the test based on age, vaccine history, and practical needs.
Other meanings: packs per day and postpartum depression
In the social history, ppd is a smoking measure. "Smoker, 1 ppd x 20 yrs" means one pack a day for twenty years, which gives 20 pack years. This lowercase use is common in admission notes and lung cancer screening forms.
In obstetric, pediatric, and behavioral health notes, PPD can mean postpartum depression, a common and treatable mood condition after childbirth. Many clinics screen for it at postpartum and newborn visits.
| Meaning | Where you see it | Clue |
|---|---|---|
| Purified protein derivative | Screening records, lab section | Mentions mm, forearm, placed or read |
| Packs per day | Social history | A number before it, like 0.5 ppd |
| Postpartum depression | OB, pediatric, mental health notes | Mentions delivery, mood, screening score |
Questions worth asking
- When exactly should I come back to have the test read?
- Does a past BCG vaccine change how my result is read?
- Would a blood test suit me better?
- If the result is positive, what are the next steps?
For related short forms, the lab and test abbreviation hub lists tests such as CXR that often follow a positive skin test. The HX page covers how history sections, where packs per day appears, are written.
This page explains a common abbreviation. Questions about your own screening result or mood after birth are best taken to your nurse, doctor, or midwife.
Frequently asked questions
What does PPD mean on a medical form?
On a job, school, or clinic form, PPD usually means the tuberculin skin test for TB. The form may ask for the date placed, the date read, and the size in millimeters.
Is a PPD the same as a TB test?
It is one type of TB test, the skin test. A blood test called IGRA is the other common option.
What does 1 ppd mean in a smoking history?
It means one pack of cigarettes per day. Clinicians multiply packs per day by years smoked to get pack years.
What does PPD mean after pregnancy?
In postpartum notes, PPD means postpartum depression. It is common and treatable, and clinicians often screen for it at follow up visits.