Vitamin D: Important for Prevention of Osteoporosis, Cardiovascular Heart Disease, Type 1 Diabetes, Autoimmune Diseases, and Some Cancers

Michael F. Holick, MD, PHD

Disclosures

South Med J. 2005;98(10):1024-1027. 

In This Article

Consequences for the Skeleton of Vitamin D Deficiency

Vitamin D deficiency during the first 2 years of life results in rickets. In adults, vitamin D deficiency can cause or exacerbate osteoporosis and induce osteomalacia. Vitamin D deficiency results in a decrease in the efficiency of intestinal calcium absorption, which results in a decrease in ionized blood calcium. The calcium sensor in the parathyroid glands respond by increasing the production of parathyroid hormone (PTH).[4] PTH interacts with its receptor on the osteoblasts to increase the RANKL. This signal induces preosteoclasts to become mature osteoclasts. The action of osteoclasts dissolving bone matrix and releasing calcium into the extracellular space increases the porosity of the skeleton. PTH stimulates tubular reabsorption of calcium in the kidney, but also causes phosphorus loss into the urine. It is this PTH-induced phosphaturia that causes the serum phosphorus levels to be low or low-normal. This subtle effect on serum phosphorus levels has serious consequences for the skeleton because there is an inadequate calcium-phosphate product to sustain normal bone mineralization. Thus, although the osteoblasts are functioning normally and lay down the collagen matrix, the inadequate calcium × phosphate product is inadequate to mineralize the matrix properly. This results in the classic picture of osteomalacia, that is, widened osteoid seams on bone biopsy.[5]

Osteoporosis does not cause bone pain. However, poorly mineralized bone, that is, osteomalacia, can cause isolated or generalized aching in the bones as well as muscle pain and muscle weakness.[6,7,8,9,10] Recently, Plotnikoff and Quigley[7] reported that 163 patients 10 to 65 years of age who presented to Minnesota Hospital with nonspecific muscle aches and bone pain more than 90% had severe vitamin D deficiency.[8] Similarly, Glerup et al[11,12] reported that 88% of Arab women living in Denmark with muscle weakness and bone pain were severely vitamin D deficient. Vitamin D deficiency also causes muscle weakness and therefore increases risk of the elderly to fall and thereby fracture.

Typically patients with nonspecific muscle aches and pain and bone discomfort are given the diagnosis of fibromyalgia, myositis, or chronic fatigue syndrome. Malabanan et al[10] reported in a black woman with severe bone discomfort and muscle aches that correction of her vitamin D deficiency not only increased her bone mineral density by almost 25% within 2 years but also gave her complete relief of her muscle aches and bone discomfort.

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