Protein-Energy Malnutrition Workup

Updated: Mar 11, 2019
  • Author: Hadi Atassi, DO; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Approach Considerations

In suspected cases of protein-energy malnutrition, it is imperative to perform a thorough and comprehensive metabolic and nutritional assessment. It begins with a detailed history, including dietary, medical, and pharmacologic (medications). It is essential to perform a thorough physical examination, including height, weight, and other growth measurements to be detailed below. In addition, it is important to perform necessary laboratory and radiologic testing. Combined, these steps should help clinicians to diagnose and assess the severity of protein-energy malnutrition.

In a study that compared 21 hospitalized children with kwashiorkor, 19 hospitalized children with marasmus, 78 children with stunted growth, and 79 children with nonstunted growth, the metabolic profiles differed between children with kwashiorkor and those with marasmus at admission, and both phenotypes were metabolically distinct from either community control group. [2] Most metabolites (128 of 141; 91%) were lower in children with kwashiorkor than in those with marasmus, with significant differences in several amino acids and biogenic amines, including those of the kynurenine-tryptophan pathway. Differences in several phosphatidylcholines and some acylcarnitines were also present. Levels of amino acids and biogenic amines generally improved with nutritional rehabilitation, but measurements of most sphingomyelins and phosphatidylcholines did not. [2]


Laboratory Studies

The following laboratory studies are recommended in the workup of protein-energy malnutrition:

  • Complete blood cell (CBC) count
  • Electrolyte levels (potassium, calcium, phosphate, magnesium)
  • Blood urea nitrogen
  • Serum albumin and prealbumin (transthyretin) levels
  • Micronutrient levels: Zinc, iron, vitamin D

Significant findings in kwashiorkor include hypoalbuminemia (10-25 g/L), hypoproteinemia (transferrin, essential amino acids, lipoprotein), and hypoglycemia. Plasma cortisol and growth hormone levels are high, but insulin secretion and insulinlike growth factor levels are decreased. The percentage of body water and extracellular water is increased. Electrolytes, especially potassium and magnesium, are depleted. Levels of some enzymes (including lactase) are decreased, and circulating lipid levels (especially cholesterol) are low. Ketonuria occurs, and protein-energy malnutrition may cause a decrease in the urinary excretion of urea because of decreased protein intake. In both kwashiorkor and marasmus, iron deficiency anemia and metabolic acidosis are present. Urinary excretion of hydroxyproline is diminished, reflecting impaired growth and wound healing. Increased urinary 3-methylhistidine is a reflection of muscle breakdown and can be seen in marasmus.

Malnutrition also causes immunosuppression, which may result in false-negative tuberculin skin test results—and the subsequent failure to accurately assess for tuberculosis.


Other Tests

One way to further evaluate patients for protein-energy malnutrition is to look at his or her measurements, or anthropometrics. A clinical tool, known as a Z-score, can be used to describe a person's weight-for-height and height-for-age relative to the rest of the population. The calculator takes into account the individual's age in months, length in centimeters, and weight in kilograms. As discussed later, any score greater than -2 indicates no stunting or wasting, whereas any up to -3 indicates severe stunting or wasting; any score in between these indicates moderate stunting or wasting.

Another way to screen for malnutrition is the mid-upper arm circumference. It is an accurate and efficient screen method, especially when resources are limited. The measurement is taken using the circumference of the left upper arm at the halfway point between the tips of the shoulder and elbow. [46]


Skin biopsy and hair-pull analysis may be performed (see Histologic Findings).


Histologic Findings

In an examination of skin biopsy samples taken from 20 children with protein-energy malnutrition (using hematoxylin and eosin staining, as well as staining for collagen, elastic fibers, mucopolysaccharides, and melanin), Thvaraj and Sesikeran found variable degrees of hypertrophy of the stratum corneum with atrophy of both the stratum granulosum and the prickle cell layers. [47]  A large amount of melanin was also found in the basal layer in all samples. Moreover, there was a reduced amount of collagen and associated crowding of elastic fibers.

In kwashiorkor, microscopic studies of hair have revealed a decrease in the proportion of anagen follicles. The anagen hairs were usually abnormal, exhibiting severe atrophy and shaft constriction. Most of the hairs examined were in the telogen phase, and the loss of pigment was consistent with the lack of melanin production during the telogen cycle.

In patients with marasmus, essentially no hairs were in the anagen phase, with a shift to the telogen phase. Many more broken hairs were found in patients with marasmus when compared to patients with kwashiorkor. Hair analysis has been advocated as a useful diagnostic procedure for both conditions.

McKenzie et al found that childhood malnutrition correlates with a reduction in the total melanin content of scalp hair. [48]


Imaging Studies

Computed tomography (CT) scanning or magnetic resonance imaging (MRI) of the brain in patients with protein-energy malnutrition can show cerebral atrophy and ventricular dilatation. One study showed that 75% of children with protein-energy malnutrition had abnormal MRI findings, including all with cerebral atrophy and 75% with concurrent ventricular dilatation. [49]

X-rays of the hand and wrists can also be obtained to assess bone formation and determine if differences exist between chronologic age and comparisons to children of similar age and gender. Bone density scans can also be considered if it is believed that the patient is at risk for osteopenia; however, this imaging modality is generally not recommended in children. [50]



The World Health Organization (WHO) classification for children with protein-energy malnutrition is outlined below. [46]

Infants younger than 6 months 

No gold standard exists for infants younger than 6 months. It is recommended that clinicians follow the same criteria used for older children. [51]

Children aged 6-59 months

Z-score: Weight-for-height and height-for-age, relative to the rest of the population

Severe acute malnutrition (Any of the following three findings)

  • Mid-upper arm circumference of less than 115 mm 
  • Z-score less than -3
  • Bilateral pitting edema

Moderate acute malnutrition

  • Mid-upper arm circumference of 115-124 mm
  • Z-score -2 to -3

Stunting (chronic malnutrition)

  • Severe: Z-score less than -3
  • Moderate: Z-score of -2 to -3