Fecal calprotectin in pediatric gastrointestinal diseases: Pros and cons

Table 1 Comparison between serum and fecal calprotectin

Aspect	Serum calprotectin	Fecal calprotectin
Purpose	Marker of systemic inflammation	Marker of intestinal inflammation
Source	Neutrophils in the bloodstream	Neutrophils in the intestinal mucosa
Production	Neutrophils release calprotectin into the bloodstream during systemic inflammation	Neutrophils migrate to gut mucosa during inflammation, releasing calprotectin into the intestinal lumen
Method of measurement	Blood tests (serum) using techniques like ELISA or immunoassays	Stool samples using techniques like ELISA
Sample ‎stability	Stable at room ‎temperature for shorter ‎periods	Requires refrigeration and ‎prompt analysis
Clinical utility	Less commonly used. Monitor overall systemic inflammatory status; response to treatment	Widely used. Distinguish between GI disorders; assess disease activity
Role in pediatric GI disorders	Less specific to GI disorders, it may not reflect the severity of GI inflammation	Highly specific to GI inflammation; aids in diagnosis and monitoring of GI disorders
Advantages	Provides systemic inflammation status	Non-invasive; reflects intestinal inflammation accurately
Limitations	Less specific to GI disorders; not as accurate for GI evaluation, influenced by systemic inflammation	Invasive; requires stool sample collection; influenced by extraintestinal factors
Reference range	Lower levels, < 50 μg/mL	Higher levels, < 50 μg/g
Interpretation	Limited evidence for clinical interpretation	Established cutoffs for clinical interpretation
Cost	Typically, higher cost	Generally lower cost
Availability	May require specialized testing facilities	Widely available

ELISA: Enzyme-linked immunosorbent assay; GI: Gastrointestinal.

Table 2 The different methods for measuring fecal calprotectin, including their descriptions and key characteristics

Method	Description
ELISA	The most common method for fecal calprotectin measurement‎
	Detection achieved through enzyme-linked secondary antibodies to quantify calprotectin in ‎stool samples‎
	Provides quantitative results using colorimetric or fluorescent detection techniques
	Widely available and standardized
	High sensitivity and specificity
	Relatively expensive
	Requires laboratory equipment and trained personnel
Turbidimetric immunoassay	Measures turbidity produced when antibodies react with calprotectin in the stool sample
	Simple and automated, suitable for high-throughput analysis
Fluorescence enzyme immunoassay	Similar to ELISA but uses fluorescent markers to detect calprotectin-antibody complexes in the stool sample
	High sensitivity and specificity comparable to ELISA
	Faster than traditional ELISA
	Suitable for point-of-care testing
	Less widely available than ELISA
	Requires specialized equipment and trained personnel
Lateral flow immunoassay	Rapid and user-friendly method where stool migrates along a membrane containing immobilized antibodies specific to calprotectin
	Provides quick visual results
	Suitable for point-of-care settings or resource-limited environments
Chemiluminescent immunoassay	Utilizes chemiluminescent labels to detect calprotectin-antibody complexes in the stool sample.
	Often used in automated laboratory platforms for high sensitivity and a wide dynamic range of detection
Immunochromatographic tests	Similar to pregnancy tests, uses colored lines to indicate calprotectin levels
	Easy to use, requires minimal training
	Portable and potentially suitable for home use
	Less sensitive and specific than ELISA
	Requires visual interpretation, susceptible to user error
Mass spectrometry	A highly accurate and sensitive method for fecal calprotectin measurement
	Considered the gold standard for research but not widely used in clinical ‎practice‎
	Very expensive, complex technique, not readily available
Quantum dot-based assay	Utilizes quantum dots, nanocrystals that emit fluorescent signals, for measuring fecal calprotectin
	Offers enhanced sensitivity and multiplexing capabilities
Quantitative polymerase chain reaction	Measures calprotectin mRNA in the stool sample, correlating with fecal calprotectin levels
	Provides‎ high sensitivity and specificity, suitable for research purposes
	Provides quantitative results
Point-of-care tests	Rapid tests performed at the clinic or even at home
	Faster results (minutes to hours)
	Convenient for patients and healthcare providers
	Lower sensitivity and specificity compared to ELISA
	Limited availability and higher cost per test

ELISA: Enzyme-linked immunosorbent assay.

Table 3 The changes in fecal calprotectin levels across different gastrointestinal diseases and populations

Cited literature	Gastrointestinal disease	Population	Calprotectin level	Changes in fecal calprotectin levels
Flagstad et al[52], 2010	FGID	Children between 4 and 15 yr	16 μg/g	No significant differences in FC levels between children with FGIDs and those without
Rhoads et al[61], 2009	Infant colic	Infants	413 +/- 71 μg/g vs 197 +/- 46 μg/g	FC levels were approximately twice as high in infants with colic compared to ‎control infants
Karabayır et al[62], 2021	Infant colic	Infants	651 µg/g and 354 µg/g, ‎respectively	Significantly higher FC typical infant colic ‎than in control infants
Olafsdottir et al[64], 2002	Infant colic	Infants	278 +/- 105 ‎μg/g vs 277 +/- 109 μg/g	No significant ‎difference in FC levels was detected between infants with classic infant colic and healthy infants
Pieczarkowski et al[72], 2018	FGID and IBD	Children	1191.5 μg/g. in IBD and 100 μg/g.in controls and patients with FIGDs	Patients with IBD and other inflammatory GI disorders had a significantly higher FC level than those in control
Rashed et al[66], 2022	Functional constipation	Children	23.6 ± 21.8 μg/g	No significant differences compared with healthy control
Mahjoub‎ et al[67], 2013	Functional constipation	Children	< 50 μg/g	FC was below the predetermined cutoff value of 50 μg/g
Shelly‎ et al[70], 2021	GERD	Preterm babies	-	High levels of FC in preterm babies with GERD than in their peer controls
Moorman‎ et al[71], 2021	FAPD	Children	≥ 50 µg/g	Children with FAPDs have significantly high FC, especially those with a clinically complex FAPD profile
Díaz et al[77], 2018	Non-IgE-mediated CMPA	Infants	-	No significant differences with healthy control
Zain-Alabedeen et al[78], 2023	CMPA	Infants	2934.57 µg/g vs 955.13 µg/g	Infants with positive CoMiSS had higher FC levels than those with negative CoMiSS scores with positive correlation between CoMiSS & FC
Qiu et al[79], 2021	CMPA	Infants	-	Significant FC reduction after dietary intervention
Degraeuwe et al[85], 2015	IBD	Children	was 212 µg/g	The best cut-off value to screen for IBD was 212 µg/g, with a sensitivity and specificity of 0.90 and 0.87, respectively
Foster et al[99], 2019	Crohn's disease	Children	250 µg/g	FC levels above 250 µg/g in children with Crohn's disease on Infliximab therapy may signify a risk of clinical relapse within three months
Balamtekın et al[104], 2012	Coeliac disease	Newly diagnosed children	117.2 μg/g in patients vs 3.7 μg/g in controls	Elevated levels compared to healthy controls and those on gluten-free diets. It is also higher in children with GI symptoms than those without
Shahramian et al[106], 2019	Coeliac disease	Newly diagnosed children	239.1 ± 177.3 μg/g vs 38.5 ± 34.6 μg/g in controls	a significant correlation between FC level and IgA ATGA titers
Montalto et al[107], 2007	Coeliac disease	Adults	-	No significant differences in FC levels between untreated adults with coeliac disease and the control and no significant relation between FC and lesion severity, clinical score, or degree of neutrophil infiltration
Szaflarska-Popławska et al[108], 2020	Coeliac disease	Newly diagnosed children	91.7 ± 144.8 µg/g	No significant relationship between FC and both the clinical picture and small intestinal lesions
Ojetti et al[114], 2020	COVID-19-induced gastrointestinal disorders	Adults with COVID-19	> 50 µg/g	Elevated levels associated with varying degrees of intestinal inflammation, including subclinical cases
Shokri-Afra et al[115], 2021	COVID-19-induced gastrointestinal disorders	Adults with COVID-19	124.3 vs 25.0 µg/g	Serum and‎ FC levels are not correlated with diarrhea or other gastrointestinal symptoms
Sýkora et al[127], 2010	Acute gastroenteritis	Children under 3 yr	219 μg/g in bacterial vs 49.3 μg/g in viral	FC can help tell if the AGE is caused by bacteria ‎or viruses
Duman et al[128], 2015	Infectious gastroenteritis	Children with bacterial gastroenteritis	710 μg/g	Higher and persistent elevation compared to viral gastroenteritis, correlates with the severity and persistence of symptoms
Czub et al[129], 2014	Infectious gastroenteritis	Hospitalized children with severe gastroenteritis	20 (viral) vs 55 (Bacterial) vs 4 (healthy control) ug/mL	FC cannot differentiate between severe viral from bacterial gastroenteritis
Rumman et al[139], 2014	Cystic fibrosis	Children with cystic fibrosis	94.29 μg/g	Elevated levels reflect bacterial overgrowth and correlate with the severity of gastrointestinal symptoms

CMPA: Cow milk protein allergy; CoMiSS: Cow’S milk-related-symptom- scores; FAPD: Functional Abdominal pain disorders; FC: Fecal calprotectin; GERD: Gastroesophageal reflux disease; IBD: Inflammatory bowel diseases; ATGA: Anti-tissue transglutaminase; GI: Gastrointestinal; COVID-19: Coronavirus disease 2019.

Table 4 Factors influencing inconsistent levels of fecal calprotectin in various pediatric gastrointestinal disorders

Factors	Influence on fecal calprotectin levels
Demographic factors	Age; higher in infants and younger children
Dietary factors	The diet that increases FC includes inflammatory Foods (such as saturated fats, refined sugars, and processed ingredients), food Sensitivities and Allergies, Alcohol and Caffeine, and dehydration. The diet that decreases FC includes hydration, high fiber intake (such as fruits, vegetables, whole grains, and legumes), Omega-3-containing foods (such as fatty fish (e.g., salmon, mackerel, sardines), flaxseeds, and walnuts), and prebiotics and probiotics
Medication usage	Drugs that could increase FC levels: Prolonged use of NSAIDs, antibiotics, PPIs, and antidiarrheal medications such as loperamide. Drugs that could reduce FC levels: Corticosteroids, immunosuppressants, such as azathioprine, and methotrexate, biological agents like infliximab and adalimumab, and Probiotics
Gastrointestinal conditions	Gastrointestinal bleeding, concurrent infections
Disease-specific factors	Disease etiology (e.g., IBD vs functional GI disorders like IBS)
Disease severity	Severity of inflammation (e.g., active inflammation in acute infectious gastroenteritis or IBD flare-ups)
Host immune responses	Genetic factors, individual susceptibility to inflammation
Methodological considerations	Sampling timing, assay methodologies
Lifestyle factors	Medication usage, dietary habits

FC: Fecal Calprotectin; GI: Gastrointestinal; IBD: Inflammatory bowel disease; IBS: Irritable bowel syndrome; NSAIDs: Nonsteroidal anti-inflammatory drugs; PPI: Proton pump inhibitors.

Table 5 The advantages (pros) and disadvantages (cons) of using fecal calprotectin in various pediatric gastrointestinal disorders

Aspect	Pros	Cons
Non-invasive	Well-tolerated by pediatric patients	Collection may be challenging in certain patients
Sensitive marker	Detects intestinal inflammation accurately	Elevated in various conditions, leading to potential false positives. Elevated levels can occur in non-gastrointestinal conditions. Limited utility in certain conditions like acute infectious gastroenteritis or functional ‎disorders ‎
Disease monitoring	Helps monitor disease activity and treatment response	Does not provide information on specific cause or location of inflammation
Early detection	Allows for early detection and intervention	Interpretation may vary depending on age. Variability in cutoff values across laboratories
Differentiation	Aids in differentiating between inflammatory and non-inflammatory conditions	Limited specificity for diagnosis. Interpretation challenges requiring clinical expertise ‎
Cost-effective	Generally considered cost-effective for diagnosis and monitoring	Represents added cost for repeated testing