Pediatric Nutrition in Practice

28 Himes  Shulman

Tests of Maldigestion/Malabsorption/Enteric
Protein Loss

Analysis of the stool is a logical starting point for
the investigation of malabsorption.
(1) Fat malabsorption: fecal fat as assessed by
72-hour collection with diet record is an
accurate, albeit cumbersome tool (for pa-
tients and laboratory technicians) to quan-
titate fat malabsorption. A fecal smear with
Sudan staining gives a rough qualitative es-
timate of steatorrhea and may be useful for
screening purposes
(2) Pancreatic insufficiency: in addition to fe-
cal fat measurement, determination of fecal
elastase can be used as a measure of exo-
crine pancreas sufficiency. Its level is not af-
fected by pancreatic enzyme supplementa-
tion. Although reliable for detecting severe
pancreatic insufficiency, it is less so for
mild-to-moderate pancreatic insufficiency;
it will not identify other isolated enzyme
deficiencies (e.g. lipase) and gives falsely
low values in the presence of watery stools
unless they are lyophilized [8]
(3) Carbohydrate malabsorption: a low fecal
pH and the presence of reducing substanc-
es are indicators of unabsorbed carbohy-

drate in stool. Testing should be done on

the most liquid portion of the stool and can

be done at the bedside using the same test

strips used to measure pH and glucose in

urine

(4) Hydrogen breath testing: this test detects

the passage of carbohydrate into the colon.

Breath hydrogen is measured at baseline

and after the child is given an oral load of

the carbohydrate of interest (e.g. lactose); a

rise in hydrogen above baseline (dependent

on the sugar of interest) is diagnostic. False-

negative tests may be seen in patients re-

cently administered antibiotics. Addition-

ally, a positive test does not always correlate

with symptoms of intolerance

(5) Small-bowel bacterial overgrowth syn-

drome may be assessed in an analogous

manner using lactulose or glucose. A breath

hydrogen peak that occurs within 15–30

min of ingestion is suggestive of over-

growth

(6) Stool α 1 -antitrypsin: unlike albumin, α 1 -

antitrypsin passes into the stool undegrad-

ed and reflects enteric protein loss but does

not define etiology (can be increased in gut

graft-versus-host disease, lymphangiecta-

sia, severe heart failure, etc.)

6 Ravel R: Clinical Laboratory Medicine,

ed 6. St Louis, Mosby, 1995, pp 655, 433.

7 Guandalini S: Essential Pediatric Gastro-

enterology, Hepatology, and Nutrition.

New York, McGraw-Hill, 2005, pp 133–

134.

8 Leeds JS, Oppong K, Sanders DS: The

role of fecal elastase-1 in detecting exo-

crine pancreatic disease. Nat Rev Gas-

troenterol Hepatol 2011; 8: 405–415.

References

1 Tschudy M, Arcara K (ed): The Harriet
Lane Handbook, ed 19. Philadelphia,
Mosby, 2012, pp 639–647.
2 Kleinman R (ed): Pediatric Nutrition
Handbook, ed 6. Elk Grove Village,
American Academy of Pediatrics, 2009,
pp 573–575.
3 Benedict A, Gilger M, Klish W, Motil K,
Phillips S, Shulman R, Terrazas N,
Thomas J: The Baylor Pediatric Nutri-

tion Handbook, ed 4. Houston, Baylor

College of Medicine, 2004, pp 34–43.

4 Walker A, Goulet O, Kleinman R,

Sherman P, Shneider B, Sanderson I

(ed): Pediatric Gastrointestinal Dis-

ease, ed 4. Hamilton, BC Decker, 2004,

p 195.

5 Sauberlich H: Laboratory Tests for the

Assessment of Nutritional Status, ed 2.

Boca Raton, CRC Press, 1999.

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