One-Hour Postoperative Parathyroid Hormone Levels Do Not Reliably Predict Hypocalcemia After Thyroidectomy.

INTRODUCTION: Hypocalcemia is a well-known complication after total thyroidectomy. Studies have indicated that the presence of low postoperative parathyroid hormone (PTH) levels can predict hypocalcemia. However, definitive study designs are lacking. The aim of this study was to determine whether postoperative PTH alone can accurately predict postoperative biochemical hypocalcemia. METHODS: Under IRB approval, a prospective study of 218 consecutive patients who underwent total or completion thyroidectomy by two surgeons between June 2014 and June 2016 was performed. Biochemical hypocalcemia was defined as ionized calcium <1.13 mmol/L or serum calcium <8.4 mg/dL at any time postoperatively. Three PTH thresholds, <10, <20 pg/mL, and >50% drop in PTH 1 h postoperatively from baseline were examined. RESULTS: Postoperative PTH < 10 pg/mL had a sensitivity of 36.5% (95% CI 27.4-46.3%) and a specificity of 89.2% (95% CI 81.9-94.3%). Postoperative PTH < 20 pg/mL had a sensitivity of 66.4% (95% CI 56.6-75.2%) and a specificity of 67.6% (95% CI 58.0-76.2%). Postoperative PTH decrease >50% had a sensitivity of 63.4% (95% CI 53.2-72.7%) and a specificity of 72.5% (95% CI 62.5-81.0%). Across all PTH thresholds, the false-negative rate was 33.6-63.5% indicating that up to 64% of patients with a normal PTH level could have been discharged without appropriate calcium supplementation. The false-positive rate was 10.8-32.4% indicating that up to 32.4% of patients with low PTH could have been treated with calcium supplementation unnecessarily. CONCLUSION: Following total thyroidectomy, PTH levels are unreliable in predicting hypocalcemia. Additional prospective studies are needed to understand the true utility of PTH levels post-thyroidectomy.

Iron deficiency in goitrous schoolchildren of Semirom, Iran.

BACKGROUND: Iodine deficiency produces the spectrum of iodine deficiency disorders (IDDs): endemic goiter, hypothyroidism, cretinism, and congenital anomalies. Other factors, including goitrogens and micronutrient deficiencies, may influence the prevalence and severity of IDDs and response to iodine supplementation. This cross-sectional, descriptive study was performed in 2003 on elementary school children of Semirom, a mountainous region of Iran, where goiter was hyper-endemic in 1994, but the goiter prevalence had not decreased as expected many years after salt iodization and iodine injection. Some possible risk factors associated with goiter in that area were evaluated, and the results of iron study are presented here. METHODS: 1,869 cases were selected by a multistage cluster sampling procedure. Grade 2 goitrous children were compared with equal number of nongoitrous children for serum iron, ferritin, transferrin, thyroxin, TSH and urine iodine concentrations (UIC). RESULTS: 210 children (105 goiter grade 0 and 105 goiter grade 2) entered this sub-study. Of 210 participants, 70 children had low transferrin saturation, 13 had low serum ferritin and 9 children had both problems. There was no significant difference in goiter rate between children with low iron indices and others. There was no significant correlation between serum iron, ferritin or transferrin saturation with other variables including T4, UIC and goiter stage. CONCLUSION: The present study reveals that in the area studied, iron deficiency cannot explain the high prevalence of goiter, so other responsible factors should be investigated.