Screening Screening Tests Test results may help make a diagnosis in symptomatic patients (diagnostic testing) or identify occult disease in asymptomatic patients (screening). If the tests were appropriately ordered on... read more (along with physical examination Physical Examination Well-child visits aim to do the following: Promote health Prevent disease through routine vaccinations and education Detect and treat disease early Guide parents to optimize the child’s emotional... read more ) is an important part of preventive health care in infants, children, and adolescents.
Screening blood tests
To detect iron deficiency, clinicians should determine hematocrit or hemoglobin as follows:
In term infants: At age 9 to 12 months
In premature 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 Diagnosis Sickle cell disease (a hemoglobinopathy) causes a chronic hemolytic anemia occurring almost exclusively in blacks. It is caused by homozygous inheritance of genes for hemoglobin (Hb) S. Sickle-shaped... read more 
can be done at age 6 to 9 months if not done as part of neonatal screening.
Recommendations for blood testing for lead exposure Lead Poisoning Lead poisoning often causes minimal symptoms at first but can cause acute encephalopathy or irreversible organ damage, commonly resulting in cognitive deficits in children. Diagnosis is by whole... read more vary by state. In general, testing should be done between ages 9 months and 1 year in children at risk of exposure (those living in housing built before 1980) and should be repeated at 24 months. If the clinician is not sure of a child’s risk, testing should be done. 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 US, 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 Diagnosis Dyslipidemia is elevation of plasma cholesterol, triglycerides (TGs), or both, or a low high-density lipoprotein cholesterol level that contributes to the development of atherosclerosis. Causes... read more 
is indicated for all children between 9 years and 11 years of age and again between 17 years and 21 years of age. Most useful is a fasting lipid profile. Cholesterol screening is indicated for children between ages 1 year and 8 years and between ages 12 years and 16 years only if they have a family history of high cholesterol or coronary artery disease or risk factors for coronary artery disease (eg, diabetes, obesity, hypertension).
Hearing tests
(See also Hearing Impairment in Children Hearing Impairment in Children Common causes of hearing loss are genetic defects in neonates and ear infections and cerumen in children. Many cases are detected by screening, but hearing loss should be suspected if children... read more 
.)
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* Normal Hearing in Very Young Children* Screening (along with physical examination) is an important part of preventive health care in infants, children, and adolescents. To detect iron deficiency, clinicians should determine hematocrit... read more ).
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 Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss (1). More than 10% of people in the US have some degree of hearing loss that compromises their... read more 
can be done in the primary care setting; most other audiologic procedures (eg, otoacoustic emission testing Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss (1). More than 10% of people in the US have some degree of hearing loss that compromises their... read more , brain stem auditory evoked response Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss (1). More than 10% of people in the US have some degree of hearing loss that compromises their... read more ) 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; the testing should include 6,000- and 8,000-Hz high frequencies.
Tympanometry Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss (1). More than 10% of people in the US have some degree of hearing loss that compromises their... read more , 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.
Tuberculosis testing
A tuberculosis screening test Screening for TB Tuberculosis (TB) is a chronic, progressive mycobacterial infection, often with a period of latency following initial infection. TB most commonly affects the lungs. Symptoms include productive... read more 
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.
Screening for sexually transmitted diseases
Routine laboratory screening for common sexually transmitted diseases (STDs) 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 injection drugs, or have another STD) should be tested yearly.
Adolescents should not be routinely screened for cervical dysplasia until they are age 21.
Screening for hepatitis C infection
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 Screening Hepatitis C is a common cause of chronic hepatitis. It is often asymptomatic until manifestations of chronic liver disease occur. Diagnosis is confirmed by finding positive anti-HCV and positive... read more .)
