Endogenous faecal calcium in chronic malabsorption syndromes and in intestinal lymphangiectasia

Endogenous faecal calcium was measured by an isotopic technique in five patients with protein-losing enteropathy due to intestinal lymphangiectasia and in ten patients with chronic malabsorption due to severe Crohn's disease (one patient) or extensive small-bowel resection (nine patients). In most patients absorption of dietary calcium and calcium balance were also determined. Endogenous faecal calcium and digestive juice calcium were highly increased in 3 patients with intestinal lymphangiectasia and normal or subnormal in the remaining 12 patients. Absorption of dietary calcium was normal in patients with intestinal lymphangiectasia but extremely low in most patients with chronic malabsorption syndromes. It is concluded that a net loss of calcium in stools in patients with intestinal lymphangiectasia is due to increased endogenous faecal calcium. In contrast, a net loss of calcium in stools in patients with extensive small-bowel resection is due to decreased absorption of dietary calcium with normal or almost normal endogenous faecal calcium.