A deficiency of vitamin D makes it difficult for the body to keep enough calcium in the bloodstream. When there are insufficient levels of vitamin D, production of a protein that promotes uptake of calcium by cells lining the intestines slows. This allows calcium to pass through the intestines without being absorbed. The arathyroid glands sense the low blood levels of calcium and secrete more parathyroid hormone.
The increasing levels of parathyroid hormone cause calcium to be released from the bones and retained in the kidneys. When there is a severe deficiency of vitamin D in childhood, the bones fail to mineralize properly. Bones are most susceptible to low vitamin D levels when the bones are growing rapidly. With severe eficiency, the arms and legs become bowed—this is called rickets. Rickets can also result in delayed closure of the soft spots (fontanels) of the skull in infants. In very severe cases, low levels of blood calcium affect the nerves and seizures may result.
Deficiency Risk Factors
Breast-fed infants not exposed to sunlight.
The elderly have less ability to synthesize vitamin D in the skin.
Institutionalized people of all ages.
People with dark skin.
People who live in cold climates.
Vitamin D deficiency can also harm adults. Adult bones can slowly become deficient in calcium and phosphorus. This can result in soft bones, known as osteomalacia. Osteomalacia can cause a bent posture and bowed legs from chronic vitamin D deficiency.
Vitamin D deficiency can be a contributor to osteoporosis. Without enough vitamin D, the bones cannot properly mineralize. In addition, increased parathyroid hormone increases the loss of bone minerals. Lowered risk of osteoporotic fracture has been found when the daily intake of vitamin D was 600 to 700 IU as opposed to lower doses.
The increasing levels of parathyroid hormone cause calcium to be released from the bones and retained in the kidneys. When there is a severe deficiency of vitamin D in childhood, the bones fail to mineralize properly. Bones are most susceptible to low vitamin D levels when the bones are growing rapidly. With severe eficiency, the arms and legs become bowed—this is called rickets. Rickets can also result in delayed closure of the soft spots (fontanels) of the skull in infants. In very severe cases, low levels of blood calcium affect the nerves and seizures may result.
Deficiency Risk Factors
Breast-fed infants not exposed to sunlight.
The elderly have less ability to synthesize vitamin D in the skin.
Institutionalized people of all ages.
People with dark skin.
People who live in cold climates.
Vitamin D deficiency can also harm adults. Adult bones can slowly become deficient in calcium and phosphorus. This can result in soft bones, known as osteomalacia. Osteomalacia can cause a bent posture and bowed legs from chronic vitamin D deficiency.
Vitamin D deficiency can be a contributor to osteoporosis. Without enough vitamin D, the bones cannot properly mineralize. In addition, increased parathyroid hormone increases the loss of bone minerals. Lowered risk of osteoporotic fracture has been found when the daily intake of vitamin D was 600 to 700 IU as opposed to lower doses.
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