I've never heard of it which made me look into it and this is what I found. I started with the definition and got this:
of, relating to, or promoting secretion; also : produced by secretion
From there I got:
Causes:
Drug-Induced Diarrhea
Secretory villous adenoma of rectum
Small bowel total villous atrophy
Intestinal Lymphoma
Chronic infections (granulomatous)
Pseudopancreatic Cholera Syndrome
Ileocolic resection
Inflammatory Bowel Disease
Usually inflammatory Diarrhea
Crohn's Disease
Ulcerative Colitis
Microscopic colitis (e.g. Lymphocytic Colitis)
Diverticulitis
Endocrine Causes
Hyperthyroidism
Medullary Thyroid Carcinoma
Islet Cell Tumor
Gastrinoma (Zollinger-Ellison Syndrome)
Vipoma (Watery Diarrhea, Hypokalemia, achlorhydria)
Malignant Carcinoid syndrome
Mastocytosis
Pheochromocytoma
Collagen Vascular Disease
Systemic Lupus Erythematosus
Scleroderma
Mixed connective tissue disease
Now I bet that answers your question
Too many causes but I did bold the thyroid as a possible cause! Sorry
Good luck!
Re: secretory diarrhea 
