Vitamin D Deficiency & Pth

An important result of a vitamin D deficiency is amplification of parathyroid hormone. Together, vitamin D and parathyroid hormone affect the regulation of your body's calcium levels. Calcium is involved in functions of bone growth, muscles, nerves and other body systems. Low vitamin D, which leads to high parathyroid hormone, may result in bone diseases such as osteoporosis and rickets.

Vitamin D

Adequate vitamin D levels promote proper calcium absorption during digestion. Vitamin D is not present in many foods but easily acquired from sunlight and dietary supplementation. The vitamin is activated in your skin by UV radiation. Exposing your arms and legs to midday sunlight five to 30 minutes per day supplies your body with required amounts of vitamin D, thus allowing dietary calcium absorption.

Parathyroid Hormone

Your parathyroid glands release parathyroid hormone to mobilize calcium from bones, enhance absorption of calcium from the intestines and prevent calcium loss in urine. Decreased levels of blood calcium or phosphorus stimulate the release of parathyroid hormone, or PTH. Both too much PTH and too little PTH result in detrimental effects. Hyperparathyroidism, which is too much PTH, becomes apparent with either kidney disease or low vitamin D levels.

Relationship of Vitamin D to PTH

When low vitamin D levels prevent calcium absorption from the small intestine, your parathyroid glands are stimulated to release PTH. Secondarily, the PTH causes the release of calcium from your body's bones. Continual stimulation of PTH results in decalcification of the bones, which results in softened bones and fractures. Bone loss that is subsequent to low levels of vitamin D plays a significant role in age-related bone loss. Sufficient vitamin D may be more important than calcium intake to maintain normal PTH levels.

Complications

Hyperparathyroidism, secondary to low vitamin D levels, is usually diagnosed before symptoms appear. Because symptoms of vitamin D deficiency are common to many other disease processes, such symptoms may go unnoticed or misdiagnosed. Long-term high PTH results in damage and dysfunction to other organs and tissues, such as the kidneys and heart. In pregnant women, low levels of calcium leading to high PTH may cause extremely low levels of calcium in newborns.

Prevention

Dietary changes to correct a vitamin D deficiency and avoid high PTH are easily attainable. The Institute of Medicine recommends daily vitamin D intake for children through adults at 200 IU per day. Over 50 years of age it recommends 400 IU and for those over 70 it is 600 IU. A deficiency warrants aggressive vitamin D supplementation at 1000 IU per day. Increasing foods high in vitamin D, such as fatty fish or fortified milk, helps prevent deficiency as well. Skin exposure to sunshine is an alternative prevention but may not be a viable choice for home-bound elderly or a society prohibiting skin exposure.