Clinical Significance of Vitamin D Deficiency in Primary Hyperparathyroidism, and Safety of Vitamin D Therapy

Nasser Mikhail, MD, MSc


South Med J. 2011;104(1):29-33. 

In This Article

Diagnostic Importance of Normalization of Vitamin D Status

A laboratory abnormality frequently encountered during the work up for osteoporosis is the presence of high serum PTH levels coupled with repeatedly normal serum calcium (both total and ionized) concentrations. In this setting, measurement of circulating 25-OHD levels (and their repletion if low) will aid in distinction between the following three conditions:

  1. Secondary hyperparathyroidism (HPT). In this case, PTH values will return to normal range with replenishment of vitamin D stores, while calcium levels remain within normal limits.[15]

  2. Concomitant PHPT and vitamin D deficiency. In some cases of PHPT, hypercalcemia may be masked by concomitant vitamin D deficiency. Thus, adequate supplementation of vitamin D will lead to emergence of frank hypercalcemia with persistence of elevated PTH levels; ie, vitamin D therapy uncovers the diagnosis of PHPT.[1]

  3. Normocalcemic HPT. This variant of PHPT is characterized by high serum PTH, but consistently normal plasma calcium concentrations after the exclusion of all causes of secondary HPT, including vitamin D deficiency.[23] If normocalcemic HPT coexists with vitamin D deficiency, PTH levels remain elevated, and calcium values remain within normal limits even after the correction of 25-OHD levels.[15]


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