Pediatric Nutrition in Practice

Use of Laboratory Measurements in Nutritional Assessment 27

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phase response ( table  3 ). Appreciating the posi-
tive and negative acute-phase reactants will help
avoid misinterpretation of data. Another limita-
tion of measuring serum proteins is that their
manufacture is tied to hepatic synthetic function.
Therefore, in a child with advanced liver disease,
low serum protein may not necessarily ref lect a
lack of substrate but rather a lack of synthetic
function. Finally, their concentrations are also
susceptible to changes in hydration status and
f luid shifts, and these changes may occur rapidly
(e.g. increased vascular permeability associated
with sepsis or trauma).

Vitamins and Minerals

The decision to evaluate vitamin and mineral
stores should take into account the suspected
underlying pathophysiology (e.g. measurement
of fat-soluble vitamins in conditions associated
with fat malabsorption, such as celiac disease or
cystic fibrosis). Frequently, signs and symptoms
of nutrient deficiency overlap with one another,
underscoring the importance of an informed ap-
proach to laboratory investigation. An often
overlooked class of patients prone to malnutri-
tion are those with absent (surgically resected) or
diseased (Crohn’s disease, small-bowel bacterial

overgrowth syndrome) terminal ilea. Deficiencies

of vitamin B 12 , vitamin K and zinc are prevalent

in these patients.

Finally, the potential effects of therapeutic

drugs are important considerations. An exhaus-

tive list of these interactions is beyond the scope

of this text; however, some important nutrient-

specific examples are shown in table 1.

Ta b l e 2. Serum proteins used in the assessment of vis-

ceral protein stores

Protein Half-life

Albumin 20 days

Prealbumin (transthyretin) 2 days

Retinol-binding protein 12 h

Ta b l e 3. Serum proteins in the acute-phase response

Positive acute-phase

reactants

Negative acute-phase

reactants

α 1 -Antitrypsin Albumin

C3 complement Prealbumin (transthyretin)

C-reactive protein Retinol-binding protein

Ceruloplasmin Transferrin

Fibrinogen Thyroxin-binding globulin

Low serum albumin

? Intake? Factitious? Losses

Diet history

• Food security


• Restrictive diets


• Formula preparation

Assess volume status

Consider inflammatory state

Urine (urinalysis)

Gastrointestinal

(stool į 1 -antitrypsin)

Burns

Fig. 1. A suggested framework for investigating hypoalbuminemia in children.

Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 23–28
DOI: 10.1159/000360314