What blood work is recommended for a child suspected of malnutrition?

Recommended Blood Work for Children Suspected of Malnutrition

For children suspected of malnutrition, a comprehensive laboratory assessment should include routine electrolytes, minerals (calcium, phosphorus, magnesium), triglycerides, serum urea, hemoglobin, total lymphocyte count, and proteins with shorter half-life such as pre-albumin or retinol-binding protein. 1

Core Laboratory Tests

Essential Blood Tests:

• Electrolytes (sodium, potassium, chloride) 1
• Minerals:
  • Calcium 1
  • Phosphorus 1
  • Magnesium 1
• Triglycerides 1
• Serum urea 1

Protein Status Assessment:

• Hemoglobin 1
• Total lymphocyte count 1
• Pre-albumin (transthyretin) - reflects improving nutritional status better than albumin due to shorter half-life 1
• Retinol-binding protein - has shorter half-life and better reflects recent nutritional changes 1

Important Considerations:

• Albumin should not be used as the sole marker for malnutrition as it is commonly affected by inflammation and protein redistribution rather than nutritional status 1, 2
• No single protein is ideal as an indicator of nutritional status since all are affected by non-nutritional physiological and pathologic states 1

Additional Tests Based on Clinical Scenario

For Severe Malnutrition:

• Nitrogen excretion 1
• Nitrogen balance 1
• Plasma amino acid profile - helps characterize protein deficit 1

For Long-term Monitoring:

• Serum vitamin concentrations 1
• Trace element concentrations 1

Frequency of Monitoring

• Critically ill children, infants, or those at risk of refeeding syndrome: Daily monitoring may be required 1
• Children transitioning between parenteral and enteral feeding: Daily monitoring 1
• Clinically stable children: Measurements repeated 2-3 times per week 1

Anthropometric Measurements to Complement Blood Work

While not blood work, these measurements should be performed alongside laboratory tests:

• Mid-upper arm circumference (MUAC) - particularly valuable when weight is unreliable due to edema 1
• Weight-for-age or weight-for-height z-score measurement 1
• For moderate malnutrition assessment: MUAC between 115-135 mm or weight-for-age/weight-for-height z-score between -2 to -3 1

Special Considerations

• In severe acute malnutrition, pharmacokinetics of medications may be altered, with lower clearance for medicines metabolized in the liver 1
• When evaluating weight changes, assessment of fluid intake and output should accompany weight measurements to determine if weight changes are due to fluid shifts or actual tissue changes 1
• For children with severe malnutrition receiving antibiotics, medication dosing may need adjustment 1

Common Pitfalls to Avoid

• Relying solely on albumin as a marker of malnutrition 1, 2
• Failing to account for fluid status when interpreting weight changes 1
• Not repeating measurements frequently enough in critically ill or rapidly changing patients 1
• Overlooking the need for vitamin and trace element assessment in long-term cases 1
• Interpreting isolated laboratory values without considering the clinical context and anthropometric measurements 1, 3