Early parathyroid hormone laboratory abnormalities related to therapeutic radiation of neck: an Egyptian experience

The effect of neck radiation on parathyroid hormone (PTH) is studied on concern as late effect of radiotherapy for benign or malignant diseases. However, the early effect on PTH is still in debate and need further evaluations. We aimed, in our study, to assess early effect of neck radiation on PTH, and related calcium and phosphorus levels. Patients diagnosed with breast or head and neck cancer who planned to received radiotherapy to neck as a definite or a part of their treatment enrolled in this prospective single-arm study from June 2012 to June 2013. Laboratory assessment of PTH, serum calcium, phosphorus and albumin was obtained before starting radiotherapy, 3 weeks and 3 months after radiation. Fifty-two patients included 24 (46.2 %) males and 28(53.8 %) females. Median age of diagnosis was 55 years. Thirty-six patients had head and neck cancer, while 16 patients were diagnosed as breast cancer. The difference in PTH and calcium levels before and after radiotherapy was statistically significant (P = 0.014 and P = 0.001 for 3 weeks and P = 0.015 and P = 0.004 for 3 months, respectively); even after correction of calcium level according to albumin level, the same results were obtained, while there was no significant difference in their levels after 3 weeks in comparison with 3 months after radiotherapy. The variation of level of phosphorus was not significant. PTH and calcium can be affected early with neck radiation, so follow-up of calcium and PTH level is mandatory for cases that will receive neck radiotherapy.