Table 5.

Warning signs of primary immunodeficiency for gastroenterologists.

Clinical events	PID	Laboratory tests (*see Table 2)
Chronic diarrhea	Antibody deficiencies	AMI
Inflammatory bowel disease	Combined immunodeficiencies (babies)	AMI, CMI
Chronic giardiasis Autoimmune enteropathy + severe intractable diarrhea. Other associated diagnosis: • hypothyroidism, eczema, thrombocytopenia, autoimmune hemolytic anemia, neonatal diabetes	X-linked immune dysregulation, polyendocrinopathy and enteropathy (IPEX)	CMI, Coombs, glycemia and TSH ANA
Persistent candidiasis	Combined immunodeficiencies	CMI T-cell lymphoproliferative assay
	Chronic mucocutaneous candidiasis	Lymphoproliferation for Candida
	Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED)	Candidin test ANA and endocrine evaluation
Severe abdominal pain emulating an acute abdomen	Hereditary angioedema	Measurement and/or functional activity assay of C1INH, C4, C1q
Liver abscess mainly due to S. aureus	Chronic granulomatous disease (CGD)	P
	Hyper IgE syndrome (HIES)	Serum IgE, eosinophilia Specific score
Hepatobiliary infection due to C. parvum	CD40 ligand (L) deficiency	AMI
Inflammatory bowel disease in babies	CGD	P
	Deficiencies of interleukin 10 (IL-10) or interleukin 10 receptor (IL-10R)	II

Adapted from Costa-Carvalho et al.⁵