Vitamin deficiency and vitamin K deficiency. In the medical literature, any of these may also be called by names on the pattern of "hypovitaminosis" or "avitaminosis" + "[letter of vitamin]", for example, hypovitaminosis A, hypovitaminosis C, hypovitaminosis D. Conversely hypervitaminosis is the syndrome of symptoms caused by over-retention of fat-soluble vitamins in the body. Vitamin deficiency A vitamin deficiency can cause a disease or syndrome known as an avitaminosis or hypovitaminosis. This usually refers to a long-term deficiency of a vitamin. When caused by inadequate nutrition it can be classed as a "primary deficiency", and when due to an underlying disorder such
Vitamin D deficiency with primary hyperparathyroidism) or with hypoparathyroidism. Patients with chronic liver disease or intestinal malabsorption disorders may also require larger doses of vitamin D (up to 40,000 IU or 1 mg (1000 micrograms) daily). The estimated percentage of the population with a vitamin D deficiency varies based on the threshold used to define a deficiency. Recommendations for 25(OH)D serum levels vary across authorities, and probably vary based on factors like age; calculations for the epidemiology of vitamin D deficiency depend on the recommended level used. A 2011 Institute of Medicine (IOM) report set the sufficiency level at 20 ng/ml (50 nmol/l),