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Allcare Medical Clinic

Providing General Medical Care Since 1986...

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How we interpret your PPD (Tuberculin Skin Test-TST) results?
(The information provided herein is general and not updated regularly. Please consult with physician)
Section A: We will document the findings of your TST results and then interpret the results as below..

Date TST Admin:__________ Date TST Read:____________ Results: ________mm of Induration
 If your TB skin test (TST) reaction size is 
14 mm or less

Your TB skin test results are normal/negative andno chest x-rays are needed.

25 mm or more

Your TB skin test reaction is positive (5 mm or more) per USCIS guidelines.

Positive TB skin test (TST) means you may have been exposed to TB germs recently or in the past, and these germs can remain inactive in your body without causing any disease, a condition called “latent TB infection”.  A chest x-ray is necessary to rule out the presence of TB disease. Read further Section B below:

Section B: If your chest x-ray shows any evidence of active TB disease (or if you have any signs or symptoms suggestive of TB disease regardless of TST reaction, you are required to have further evaluation & treatment with health dept/TB clinic or a local specialist. Medical clearance (for USCIS) may not be granted until you bring in proof/documentation that you have completed the required evaluation &/or treatment.

Section C:If your chest x-ray does not show any evidence for active TB disease, then you are medically cleared for tuberculosis for this examination. But you will be recommended to follow up with your doctor for latent tuberculosis (TB skin test positive but no TB on chest x-ray). Your doctor may decide to treat your latent TB based on your risk factor(s) and size of TB skin test reaction.

If your chest x-ray is abnormal (other than TB disease), you will need to follow up (not required by USCIS) with your physician for further evaluation and treatment.

Size of TB test reaction and risk factor(s) as below that you doctor may consider in making recommendations about who needs preventive treatment for latent tuberculosis.

A TB skin test reaction of 5 mm or more is considered positive (for treatment purpose) if you are in one of these groups. (Item #1 thru 5)

Advice for latent TB infection

If any one or more item (s) in the section on the left apply to you AND your chest x-ray is normal (No TB disease), then you are considered to have latent TB infection, (Class B – latent TB infection needing an evaluation for

treatment per USCIS guidelines)

Latent TB nfection means you have these

TB germs in your body in “inactive forms”

not causing any problems at this time.

But these germs can become active in future to cause a serious disease,

called tuberculosis which can be dangerous to your health and

infectious to other people around you.



to consider further evaluation & treatment.

Treating a latent TB infection now can

decrease your chances of

developing TB disease in future.

Most commonly used treatment generally includes 9 months of Rx, called

Isoniazid (INH) & Vitamin B6 to

minimizes some of the side

effects from INH.

Further Information may be obtained

from your medical doctor

or call us at

(425) 255-0055

to make an appointment to

discuss further.

1. HIV infected persons

2. Recent contacts of TB cases

3. Patients with transplanted organs

4. Other immunosuppressed patients (receiving the equivalent of 15mg/day or more of prednisone for at least one month)

5. Fibrotic lesions (not granulomas) on chest x-ray (required further evalaution per USCIS guidelines)


A TB skin test reaction of 10 mm or more is considered positive (for treatment purpose) if you are in one of these groups. (Item# 6 thru 12)

6. Recent arrival (within the last 5 years) in USA from a country where TB disease is highly prevalent.

7. Has high risk factor? (previous TB per CXR & rec’d incomplete or no Tx, A child with recent TB within past 2 years, Cancer of head/neck, Chronic mal-absorption syndromes, Diabetes, End stage renal disease, Leukemia, Hodgkin’s or other hematological

diseases, HIV infection, Illicit drug use, Intestinal bypass, Gastrectomy, low body weight (>10% below ideal, prolonged steroid or other immunosuppressive therapy, silicosis, other

8. Injection drug users.

9. Recent converters (10 mm increase over 2 yrs

10. Resident/employees of high risk congregate settings

such as correction center, nursing home, hospital, homeless shelters

11. Mycobacterial(TB bacteria) laboratory personnel

12. Children <4 yrs & exposed to adults in high risk groups as above.


13. None of the above apply to you, then TB reaction size of 15 mm or more is considered positive (for treatment purpose).