Parathyroid hormone in coronary artery disease--results of a prospective study.

Parathyroid hormone (PTH) influences the calcium metabolism of many different mammalian cell types; indeed, hypertension due to changes in muscle tone is a frequent symptom of hypercalcemic hyperparathyroidism. In a blind study of 81 patients with various forms of heart disease undergoing coronary angiography, the plasma concentrations of the midcarboxyl regional PTH immunoreactivity were determined. PTH concentrations were elevated in 26 of the 56 patients exhibiting organic coronary artery disease (CAD). The plasma PTH levels were highest in those patients with CAD affecting three vessels and in patients with evidence of myocardial infarction. PTH levels were not influenced by previous drug treatments, and did not correlate to stress hormone levels. We propose that increased PTH levels may be a marker for initiation or potentiation of calcium-dependent changes in vascular smooth muscle behavior inducing coronary functional and anatomic lesions typical of CAD.