How does cystic fibrosis (CF) affect pancreatic functioning?

Updated: Sep 28, 2020
  • Author: Girish D Sharma, MD, FCCP, FAAP; Chief Editor: Kenan Haver, MD  more...
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As a part of normal digestion, stomach acid is neutralized by pancreatic bicarbonate, leading to the optimal pH for pancreatic enzyme action. Reduced bicarbonate secretion in response to secretin stimulation has been demonstrated in patients with cystic fibrosis with both pancreatic insufficiency and sufficiency. Reduced bicarbonate secretion affects the digestion so that neither endogenous nor exogenous pancreatic enzymes can work at their optimal pH.

Other factors, such as reduced water content of secretions, precipitation of proteins, and plugging of ductules and acini, prevent the pancreatic enzymes from reaching the gut. Autodigestion of the pancreas occasionally leads to pancreatitis.

Most patients with cystic fibrosis (90-95%) have pancreatic enzyme insufficiency and present with digestive symptoms and/or failure to thrive early in life. Onset of pancreatic insufficiency varies, however, and may occur in patients older than 6 months. Some patients never develop pancreatic insufficiency.

Patients with pancreatic insufficiency typically present with poor weight gain in association with frequent stools that are malodorous, greasy, and associated with flatulence and colicky pain after feeding. The combination of increased energy intake demand at baseline, the added energy intake demand of chronic disease, difficulty sustaining energy uptake because of malabsorption, and anorexia associated with ongoing lung inflammation leads to poor weight gain.

Pancreatic insufficiency predisposes patients to poor absorption of fat-soluble vitamins A, D, E, and K. Symptomatic deficiency of any of these vitamins can occur before diagnosis or as a later complication of the disease.

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