Determination of circulating parathyroid hormone levels and differential diagnosis of hypercalcemia

Parathyroid Hormone Secretion and Related Syndromes

In this article, we will get to know about the parathyroid hormone and the parathyroid gland. Its anatomy, physiology, and pathology will be delved into. There will be a brief discussion about its secretion and also about various clinical syndromes related to it. Parathormone, the parathyroid glands, regulate normal calcium and phosphorus levels in the body. An increase in the secretion of parathormone results in increased calcium uptake from the kidney, intestine, and bones, hence elevating the blood calcium level. A few mechanisms of action of this hormone are increased by the presence of vitamin D. The increase in the secretion of this hormone as compared to the normal levels is termed hyperparathyroidism. Incidence is maximum after 60 years of age. The ratio of females to males is 2:1. There are three types of hyperparathyroidism which will be described in this article. Clinical manifestations of hyperparathyroidism include skeletal disease, renal involvement, GI manifestations, psychiatric diseases, decreased neuro-muscular irritability, decreased deep tendon reflexes, muscular weakness, and atrophy. Assessment for hyperparathyroidism can be done by various diagnostic tests which are described further in this article. Medical/surgical management to cure this is also well-established nowadays. The decrease in the secretion of this hormone as compared to normal levels is termed hypoparathyroidism. Serum calcium levels are very low, serum phosphate levels are very high, and tetany can develop. The incidence is that females are more prone than males. Assessment for acute hypoparathyroidism will show positive Chvostek sign and trousseau sign, hyperactive deep tendon reflexes, and paresthesia. Assessment of chronic hypoparathyroidism will show lethargy, weakness, fatigue, cataracts, brittle nails, dry scaly skin, personality changes, and can even cause permanent brain damage. The normal secretion process of this hormone and diseases when its secretion becomes abnormal and why that happens are briefed in this article.

The causes of hypercalcemia in Okinawan patients: an international comparison

OBJECTIVE

Our objective was to determine the causes and relative prevalence of hypercalcemia in patients at a major community hospital in Okinawa, Japan. Additionally, we compared these causes of hypercalcemia with the previously published international data.

MATERIALS AND METHODS

We analyzed all patients with hypercalcemia in a community teaching hospital in Okinawa, Japan, from 1999 to 2002 and determined the cause of hypercalcemia in each patient. We also performed a literature review of the original articles describing causes of hypercalcemia in patients from Eastern as well as Western countries.

RESULTS

We identified 145 patients with hypercalcemia (median age, 69; range, 22 to 97). Major causes included malignant disorders (n=100; 69%), primary hyperparathyroidism (n=31; 21%), vitamin D-induced (n=4; 3%), and miscellaneous or unknown cause in 11 (8%). Among malignant disorders, adult T cell leukemia was the most frequent (n=35), being followed by lung cancer (n=25). Breast carcinoma was less prevalent (n=4).

CONCLUSION

The major causes of hypercalcemia are malignancy and primary hyperparathyroidism in Okinawan Japanese patients. Adult T cell leukemia and lung carcinoma are among the top leading malignancies, while breast carcinoma is less frequent in this patient population. The etiologic prevalence of hypercalcemia in the Eastern population including Okinawans is significantly different from that in the Western population.