Increased In:

• Endogenous vitamin D intoxication (in conditions such as sarcoidosis, cat scratch disease, and some lymphomas, extrarenal conversion of 25-dihydroxy to 1,25-dihydroxy vitamin D occurs with a corresponding abnormal elevation of calcium)
• Exogenous vitamin D intoxication

Decreased In:

• Bowel resection (related to lack of absorption)
• Celiac disease (related to lack of absorption)
• Inflammatory bowel disease (related to lack of absorption)
• Malabsorption (related to lack of absorption)
• Osteomalacia (related to dietary insufficiency)
• Pancreatic insufficiency (lack of digestive enzymes to metabolize fat-soluble vitamin D; malabsorption)
• Rickets (related to dietary insufficiency)
• Thyrotoxicosis (possibly related to increased calcium loss through sweat, urine, or feces with corresponding decrease in vitamin D levels)