Pediatric Nutrition in Practice

26 Himes  Shulman

total protein is predicated on normal globulin

levels, limiting its clinical usefulness. Generally, se-

rial measurements of protein status are more

meaningful than single values and an understand-

ing of their biological half-lives will dictate the

frequency of assessment ( table 2 ). A framework for

the investigation of hypoalbuminemia is shown in

figure 1.

The most important limitation to interpreting

serum protein levels is their function in the acute-

Table 1 (continued)

Test (specimen) Normal range^1 Function/description Deficiency Pitfalls to avoid

Vitamin A
(serum)

Preterm: 0.46 – 1.6 μmol/l

Term: 0.63 – 1.75 μmol/l

1 – 6 years: 0.7 – 1.5 μmol/l

7 – 12 years: 0.9 – 1.7 μmol/l

13 – 19 years: 0.9 – 2.5 μmol/l

Fat-soluble vitamin that

functions in vision,

maintenance of epithelial

tissue and immunity; 90%

stored in liver

Reversible night blindness (1st

clinical manifestation), which,

uncorrected, can progress to

corneal scarring

↓ in liver disease, zinc deficiency

[5]

↑ with oral contraceptive pill

use

Vitamin B 1

• thiamine
  (whole blood)

Measure RBC transketolase activity

<15% [2]

Water-soluble vitamin with

role in oxidative

phosphorylation and pentose

phosphate pathway

Beriberi: cardiac failure,

peripheral neuropathy ±

edema

Wernicke encephalopathy,

Korsakoff syndrome

Vitamin B 2

• riboflavin
  (whole blood)

Measure RBC glutathione

reductase activity

<20% [2]

Water-soluble vitamin that

facilitates redox reactions

Dermatitis, cheilitis, glossitis

and visual impairment

Vitamin B 6

• pyridoxine
  (plasma)

Measure pyridoxal 5′-phosphate

concentration

14.6 – 72.8 nmol/l [3]

Cofactor for enzymes in

aminotransferase reactions

including δ-aminolevulinic

acid and the manufacture of

serotonin [5]

Microcytic, hypochromic

anemia, dermatitis, cheilosis,

stomatitis, peripheral

neuropathy, seizures and ↓

AST and ALT

↓ level with isoniazid treatment

Vitamin B 12

• cobalamin
  (serum)

Neonate: 118 – 959 pmol/l

Infant/child: 148 – 616 pmol/l

Water-soluble vitamin active

in DNA synthesis and

branched-chain amino acid

metabolism

Megaloblastic anemia,

hypersegmented neutrophils

and glossitis, stomatitis,

weakness, elevated

homocysteine and

methylmalonic acid

↓ by phenytoin, proton-pump

inhibitors, neomycin and folate

deficiency

Vitamin C

• ascorbate
  (plasma)

23 – 114 μmol/l Water-soluble antioxidant

vitamin important in collagen

synthesis

Scurvy: petechial and gingival

hemorrhage, gingivitis and

poor wound healing

Vitamin D

• 25-hydroxy
  (plasma)

Summer: 15 – 80 μg/l

Winter: 14 – 42 μg/l [3]

Fat-soluble vitamin involved

in calcium and phosphorus

homeostasis

Deficiency primarily affects

bone and is called ‘rickets’;

↓ serum calcium and

phosphate,

↑ alkaline phosphatase

↓ with anticonvulsant therapy

and cholestyramine

Vitamin E
(serum)

Preterm: 1 – 8 μmol/l

Term: 2 – 8 μmol/l

1 – 12 years: 7 – 21 μmol/l

13 – 19 years: 14 – 23 μmol/l

Fat-soluble antioxidant that

protects cell membranes

Diminished deep tendon

reflexes, impaired balance and

gait

Carried in serum bound to lipid;

therefore, hyperlipidemia may

mask deficiency; vitamin E/lipid

ratio useful in these

circumstances

Zinc (plasma) 10.7 – 18.4 μmol/l Cofactor for >200 enzymes,
notably alkaline phosphatase,
RNA/DNA polymerase and
superoxide dismutase [5]

Acrodermatitis enteropathica,

also delayed wound healing,

impaired taste, growth failure,

delayed puberty and diarrhea

↑ in hemolyzed specimens

↓ in sickle cell patients,

hypoalbuminemia

(^1) All reference ranges from Tschudy and Arcara [1] unless otherwise noted.
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