Malabsorption of fat soluble vitamins (seem like the patient has celiac disease or perhaps a pancreatic issue) Low calcium = Vitamin D deficiency

• Young patient with malabsorption (intermittent diarrhea with weight loss and fat in the stool) who has low calcium and phosphorous levels, which is most consistent with vitamin D deficiency
• Key idea: Vitamin D responsible for calcium and phosphorous absorption from the GI tract (contrast with PTH which leads to increased calcium and decreased phosphate)
• Key idea: Fat soluble vitamins are vitamins A, D, E and K