Screening Tests for Infants, Children, and Adolescents

To detect iron deficiency, clinicians should determine hematocrit or hemoglobin as follows:

• In term infants: At age 9 to 12 months

• In preterm infants: At age 5 to 6 months

• In menstruating adolescents: Annually if they have any of the following risk factors: moderate to heavy menses, chronic weight loss, a nutritional deficit, or participation in athletic activity

Testing for sickle cell disease can be done at age 6 to 9 months if not done as part of neonatal screening.

Recommendations for blood testing for lead exposure vary by state. In general, a risk assessment should be performed at all well-child visits between 6 months and 6 years of age. A blood lead level test should be done if the risk assessment is positive. Universal screening at 1 and 2 years may be recommended for children who live in high prevalence areas with increased risk factors such as older housing. There is no safe blood lead level in children, and even low blood lead levels have been shown to affect IQ, ability to pay attention, and academic achievement. Effects of lead exposure cannot be corrected. In the United States, a level > 5 mcg/dL (> 0.24 micromol/L) is now used to identify children who have been exposed to lead and who require case management.

Cholesterol screening is indicated for all children between 9 years and 11 years of age and again between 17 years and 21 years of age and can be done with a non-fasting lipid profile. Cholesterol screening is indicated for children after 2 years of age but no later than 10 years of age if they have a family history of high cholesterol or early coronary artery disease or risk factors for coronary artery disease (eg, diabetes, obesity, hypertension).

(See also Hearing Impairment in Children.)

Parents may suspect a hearing deficit if their child ceases responding appropriately to noises or voices or does not understand or develop speech (see table Normal Hearing in Very Young Children).

Because hearing deficits impair language development, hearing problems must be remedied as early as possible. The clinician therefore should seek parental input about hearing at every visit during early childhood and be prepared to do formal testing or refer to an audiologist whenever there is any question of the child’s ability to hear.

Audiometry can be done in the primary care setting; most other audiologic procedures (eg, otoacoustic emission testing, brain stem auditory evoked response) should be done by an audiologist. Conventional audiometry can be used for children beginning at about age 3 years; young children can also be tested by observing their responses to sounds made through headphones, watching their attempts to localize the sound, or observing them complete a simple task. For older children, audiometry should be done once between 11 and 14 years, once between 15 and 17 years, and once between 18 and 21 years; testing for older children should include 6,000- and 8,000-Hz high frequencies.

Tympanometry, another in-office procedure, can be used with children of any age and is useful for evaluating middle ear function. Abnormal tympanograms often denote eustachian tube dysfunction or the presence of middle ear fluid that cannot be detected during otoscopic examination.

Pneumatic otoscopy is helpful in evaluating middle ear status, but combining it with tympanometry is more informative than either procedure alone.

A tuberculosis screening test using a skin test (tuberculin test) or blood test (interferon-gamma release assay [IGRA]) should be done if

• Children have been exposed to tuberculosis (eg, to an infected family member or close contact).

• They have had a family member with a positive tuberculin test.

• They were born in or recently traveled to a high-risk country (countries other than the United States, Canada, Australia, New Zealand, or Western and North European countries).

• Their parents or close contacts are new immigrants from a high-risk country or have been recently incarcerated.

IGRA is preferred for children who are considered unlikely to return to have their skin test read or for those who have received the BCG vaccine, which can cause a false-positive skin test result.

Routine laboratory screening for common STIs is indicated for all sexually active adolescents yearly.

Nucleic acid amplification tests (NAATs) are the most sensitive tests for detecting C. trachomatis and N. gonorrhoeae infection. NAATs using urine, rectal, cervical, pharyngeal, or urethral specimens are available.

All adolescents should be offered HIV screening at least once between the ages of 15 and 18 years; every effort should be made to preserve the confidentiality of the adolescent. Adolescents at increased risk of HIV infection (because they are sexually active, use or have used injection drugs, or have another STI) should be tested yearly.

Adolescents should not be routinely screened for cervical dysplasia until they are age 21.

People should be routinely screened for hepatitis C virus (HCV) infection at least once between the ages of 18 and 79 (see the U.S. Preventive Services Task Force's 2020 Hepatitis C Virus Infection in Adolescents and Adults: Screening statement and the CDC's 2020 Recommendations for Hepatitis C Screening Among Adults—United States). People at increased risk of HCV infection, including those with past or current injection drug use, should be tested for HCV infection and reassessed yearly. (See also Screening of Chronic Hepatitis C.)

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

1. U.S. Preventive Services Task Force: Hepatitis C Virus Infection in Adolescents and Adults: Screening statement (2020)

2. CDC: Recommendations for Hepatitis C Screening Among Adults—United States (2020)