Endocrine Abstracts

Introduction: Hyperparathyroidism is a disease characterized by excessive secretion of parathyroid hormone (PTH). There are three main etiologies: primary (PHPT), secondary (SHPT) and tertiary hyperparathyroidism (THPT). PHPT is characterized by abnormal regulation of PTH secretion by calcium, resulting in hypersecretion of PTH relative to the serum calcium concentration. SHPT is the overproduction of PTH in context of hypocalcemia, most frequently because of vitamin D deficiency and/or chronic kidney disease (CKD). THPT is a state of excessive secretion of PTH after longstanding SHPT and resulting in hypercalcemia.

Objectives: To evaluate the PTH requests and the causes of hyperparathyroidism in a central hospital.

Methods: Retrospective study of PTH measurements and corresponding patients’ records performed between May 2016 and June 2017. Hyperparathyroidism was defined as PTH >72 pg/ml, determined by electrochemiluminescence immunoassay. CKD was established according to the Kidney Disease Outcomes Quality Initiative guidelines. Statistical analysis was performed with SPSS software, version 20.

Results: A total of 1085 PTH measurements were recorded, corresponding to 955 patients. Of these, 349 had hyperparathyroidism. Excluding patients with insufficient clinical information (n=22), there were 327 patients (62.1% female; 68.7±0.9 years), with the following diagnosis: PHPT, n=28 (78.6% female, 64±2.6 years); SHPT n=296 (60.5% female, 69.4±1 years), THPT n=2 (100% female, 42.5±17.5 years) and 1 case of familial hypocalciuric hypercalcemia (male, 49-year-old). The causes of SHPT were: chronic kidney disease (CKD, 122); vitamin D deficiency (107); combined CKD and vitamin D deficiency (64); Paget’s disease (2) and pseudohypoparathyroidism (1). Patients with CKD (186) presented the following distribution: stage 3, n=69; stage 4, n=63 and stage 5, n=54. In the patients with hyperparathyroidism, the PTH measurement was requested by different departments: Internal medicine (127), Nephrology (69), Rheumatology (38), Endocrinology (38), Haematology (13), Infectious diseases (10), Pneumology (9), Gastroenterology (4), Neurology (4), Cardiology (4), Gynaecology (3), Oncology (3), Surgery (3) and Urology (2).

Conclusions: SHPT was the most prevalent etiology of hyperparathyroidism, particularly the one secondary to CKD, as expected because of the high prevalence of CKD in general population. Different medical specialties requested the measurement of PTH. Probably, in our institution, this is a laboratory test excessively requested, increasing medical costs without benefits for the patients.