A patient with hypercalcemia complains of constipation and fatigue. Explain the mechanistic relationship between high calcium intake and gastrointestinal symptoms.

• A. Excess calcium increases intestinal pH dramatically causing enzyme inactivation and acute malabsorption syndrome
• B. High calcium triggers immediate release of gastrin which causes diarrheal symptoms rather than constipation
• C. Hypercalcemia increases bile secretion which directly causes constipation and decreased appetite
• D. High serum calcium can slow smooth muscle contractility in the GI tract and excess unabsorbed calcium in the lumen can alter motility and cause constipation and bloating

Answer: (D)