Tests for organic causes should be done based on the history and physical examination (see Table: Organic Causes of Constipation in Infants and Children): Barium enema, rectal manometry, and biopsy (Hirschsprung disease) Plain x-rays of lumbosacral spine; MRI considered (tethered spinal cord or tumor) Thyroid-stimulating hormone and thyroxine (hypothyroidism) Blood lead level (lead poisoning) Stool for botulinum toxin (infant botulism) Sweat test and genetic testing (cystic fibrosis) Calcium and other electrolytes (metabolic derangement) Serologic screening usually for IgA antibodies to tissue transglutaminase (celiac disease) Treatment of Constipation in Children Specific organic causes of constipation should be treated.