What lab tests are recommended for a 1-year-old child with potential risk of infectious diseases and possible environmental or nutritional deficiencies?

Laboratory Testing for a 1-Year-Old Child

Anemia Screening

All 1-year-old children should be screened for anemia with hemoglobin or hematocrit testing between 9-12 months of age, with the approach (universal vs. selective) determined by population risk factors. 1

Universal Screening Populations

• Children from low-income families should receive universal anemia screening at 9-12 months, with repeat screening 6 months later (at 15-18 months) 1
• Children eligible for WIC, migrant children, and recently arrived refugee children require universal screening at these intervals 1

Selective Screening Populations

For children not in high-risk populations, screen only those with specific risk factors at 9-12 months 1:

• Preterm or low-birthweight infants 1
• Infants fed non-iron-fortified formula for >2 months 1
• Infants introduced to cow's milk before 12 months 1
• Breast-fed infants without adequate iron supplementation after 6 months 1
• Children consuming >24 oz daily of cow's milk 1
• Children with special health-care needs (chronic infections, inflammatory disorders, restricted diets, or extensive blood loss) 1

Diagnostic Confirmation

• If screening hemoglobin or hematocrit is abnormal, repeat the test to confirm 1
• Consider checking serum calcium, phosphorus, and alkaline phosphatase if there are concerns for metabolic bone disease or nutritional deficiencies 1
• Serum 25-hydroxyvitamin D and parathyroid hormone should be assessed if radiographic evidence of osteopenia exists 1
• Serum copper, vitamin C, and ceruloplasmin concentrations should be considered if the child is at risk for scurvy or copper deficiency 1

Urinary Tract Infection Screening

Urinalysis and urine culture via catheterization should be performed if the 1-year-old presents with fever ≥38°C (100.4°F), particularly in high-risk groups. 2, 3

Risk Factors for UTI at This Age

• Female sex (5-7% prevalence in febrile infants <24 months) 2
• Uncircumcised males (up to 20% risk) 2
• Fever duration >24 hours 1
• Higher fever (≥39°C) 1
• No obvious source of infection 1

Collection Method

• Urine must be obtained via catheterization rather than collection bags to avoid false-positive results (12% contamination rate vs. 26% for clean catch) 3
• Positive leukocyte esterase, nitrites, elevated leukocyte count, or positive Gram stain indicates presumptive UTI 2, 3

Additional Testing Based on Clinical Presentation

For Febrile Illness

If the 1-year-old presents with fever, additional testing depends on clinical findings 2, 3:

• Complete blood count with differential if serious bacterial infection is suspected (elevated WBC and absolute neutrophil count associated with greater SBI risk) 2, 3
• Chest radiograph only if respiratory signs/symptoms present (tachycardia out of proportion to fever, tachypnea, cough, hypoxia, or rales) 3
• Blood culture if the child appears ill or has concerning laboratory findings 2

For Trauma or Suspected Abuse

• Serum calcium, phosphorus, and alkaline phosphatase if fractures are present and abuse is suspected 1
• Liver function tests, amylase, and lipase if severe or multiple injuries identified 1
• Urinalysis to screen for occult blood in trauma cases 1

Critical Pitfalls to Avoid

• Never delay anemia screening beyond 12 months in high-risk populations, as iron deficiency can have long-term neurodevelopmental effects 1
• Never use urine collection bags instead of catheterization when UTI is suspected, as contamination rates are unacceptably high 3
• Never rely on clinical appearance alone to exclude serious bacterial infection in febrile children, as 58% of infants with bacteremia or meningitis may appear well 2
• Never start antibiotics before obtaining urine culture if UTI is suspected 2, 3