Diarrhea in patients with MTC (Medullary Thyroid Cancer) can be debilitating and, in some cases life threatening. Findings in such patients include volume depletion, renal insufficiency, and electrolyte disorders. Diarrhea can also lead to increased cost of care, reduced quality of life, and treatment delays. Not all patients benefit from conventional anti-diarrheal therapy. CASAD is proven to reduce diarrhea in humans and animals. Clays have water-binding effects, increase the absorptive capacity of the intestinal mucosa, and absorb the excess cytokines which are possible mechanisms of diarrhea in MTC. In this study, we will investigate if starting 1 g CASAD three times a day will ameliorate the severity of diarrhea in patients with MTC. Diarrhea in patients with MTC can be debilitating and, in some cases life threatening. Findings in such patients include volume depletion, renal insufficiency, and electrolyte disorders. We hypothesize that adding CASAD 3 grams/day will reduce the incidence and ameliorate the severity of diarrhea in patients with MTC.

Inclusion Criteria:

• Patients with medullary thyroid cancer
• Men and women from all ethnic and racial groups
• Diarrhea ( >=3 loose bowel movements per day)
• Duration of diarrhea of at least 1 week

Exclusion Criteria:

• Patients with MEN 2b (since these patients may have megacolon)
• Patients taking any clay products
• History of significant neurological or psychiatric disorders that would impede giving consent, treatment, or follow up.
• Patients who cannot comply with medications
• Patients whose current medication schedule would not permit an approximate 2 hour window between administration of CASAD and other scheduled medications.
• Pregnancy or lactation
• Patients receiving systemic chemotherapy (includes tyrosine kinase inhibitors)