Postoperative hypoparathyroidism after thyroid surgery

The timing of parathyroid hormone measurement defines the cut-off values to accurately predict postoperative hypocalcemia: a prospective study

PURPOSE

Serum intact parathyroid hormone (iPTH) level is an early marker of post-thyroidectomy hypocalcemia. However, lack of methodological standardization to define timing and cut-off points of iPTH measurement limit its clinical applicability. Here, we evaluated the relationship between two distinct postoperative time sampling and iPTH accuracy on predicting hypocalcemia.

METHODS

iPTH was measured within 4 h after surgery (iPTH 4 h) and on the morning of the first postoperative day (iPTH 1st PO). Hypocalcemia was defined by levels of total calcium corrected by serum albumin ≤ 8.0 mg/dL and/or by the presence of symptoms. The most accurate iPTH cut-off point for hypocalcemia prediction was established from a ROC curve comparing both time-points.

RESULTS

The study included 101 patients. The mean age was 52.4 ± 12.9 years, 93 were women (92.1%) and 69 patients underwent total thyroidectomy (68.3%). Hypocalcemia occurred in 25 patients (24.8%), of whom 12 were symptomatic. Total thyroidectomy, longer duration of surgery, surgical complications related to parathyroid glands and lower levels of iPTH 4 h and iPTH 1st PO were associated with postoperative hypocalcaemia (all P < 0.05). Using the ROC curve, the optimal cut-off points were 19.55 pg/mL and 14.35 pg/mL for iPTH 4 h and iPTH 1st PO, respectively. The comparison of the AUC showed no significant difference between these two points of evaluation (0.935 vs. 0.940; P = 0.415).

CONCLUSIONS

Serum iPTH levels measured within 4 h or on the first morning after surgery are predictors of postoperative hypocalcemia. Notably, both time-points have the same accuracy to predict postoperative hypocalcemia (with different cutoff points).

Circulating thyroid cancer biomarkers: Current limitations and future prospects

Differentiated thyroid cancer (DTC) is the most common malignancy of the endocrine system. There has been a significant increase in its incidence over the past two decades attributable mainly to the use of more sensitive diagnostic modalities. Ultrasound-guided fine needle aspiration cytology is the mainstay of diagnosis of benign disorders and malignancy. However, approximately 20% of lesions cannot be adequately categorized as benign or malignant. In the postoperative setting, monitoring of thyroglobulin (Tg) levels has been employed for the detection of disease recurrence. Unfortunately, Tg antibodies are common and interfere with Tg measurement in this subset of patients. Despite this limitation, Tg remains the sole widely used thyroid cancer biomarker in the clinical setting. In an attempt to bypass antibody interference, research has focused mainly on mRNA targets thought to be exclusively expressed in thyroid cells. Tg and thyroid stimulating hormone receptor (TSHR) mRNA have been extensively studied both for discerning between benign disease and malignancy and in postoperative disease surveillance. However, results among reports have been inconsistent probably reflecting considerable differences in methodology. Recently, microRNA (miRNA) targets are being investigated as potential biomarkers in DTC. MiRNAs are more stable molecules and theoretically are not as vulnerable as mRNA during manipulation. Initial results have been encouraging but large-scale studies are warranted to verify and elucidate their potential application in diagnosis and postoperative surveillance of thyroid cancer. Several other novel targets, primarily mutations and circulating cells, are currently emerging as promising thyroid cancer circulating biomarkers. Although interesting and intriguing, data are limited and derive from small-scale studies in specific patient cohorts. Further research findings demonstrating their value are awaited with anticipation.

Analysis of factors affecting the development of hypocalcaemia after multinodular goitre surgery

INTRODUCTION

Thyroidectomy is a common surgery performed especially in treatment of multinodular goitre. The most common post-thyroidectomy complication is a postoperative hypocalcaemia, and the percentage of postoperative hypoparathyroidism could reach even 50%. Tested group and methods: A forward-looking, randomized testing was done on a group of 113 women being subject to multinodular goitre surgery. In this article, we wish to present an analysis of the results obtained in the control group, focusing on the predicative factors which determine the development of postoperative hypocalcaemia. Obtained results: The rate of postoperative biochemical hypocalcaemia development was significantly higher in the group of patients, where the preoperative calcium concentration was lower than 2,4 mmol/l. In that group, the development of biochemical hypocalcaemia was observed in 93,7% of cases (30 out of 32 patients), in comparison with 65,3% (17 out of 26) in the group of higher preoperative concentration of calcium. The highest risk of occurrence of postoperative hypocalcaemia was borne by the total thyroidectomy, while the lowest one by the subtotal thyroid lobectomy of one lobe only.

CONCLUSIONS

A higher preoperative concentration of calcium in blood serum is related to the lower rate of occurrence of postoperative biochemical hypocalcaemia. However, no such correlation was revealed in the case of postoperative symptomatic hypocalcaemia. Lack of correlation was determined between the preoperative concentration of TSH and FT4 in blood serum and the rate of occurrence of postoperative hypocalcaemia, both symptomatic and asymptomatic. The performed statistics did not reveal a relation between the postoperative hypocalcaemia and the duration of the surgery, but a significant correlation was stated with the scope of the performed surgery. Revealing a relation between the rate of occurrence of postoperative hypocalcaemia and the experience of the surgeon performing the surgery was not successful.